Zoo 116 Introductory Invertebrate Zoology PDF

ZOO 116 (INTRODUCTORY INVERTEBRATE ZOOLOGY)  INTRODUCTION What are invertebrates?  Presence or absence of backbone/vertebral column/Spine A number of characteristics set a major divide between the animals/organisms The backbone gives a major division So we have...

ZOO 116 (INTRODUCTORY INVERTEBRATE ZOOLOGY)  INTRODUCTION What are invertebrates?  Presence or absence of backbone/vertebral column/Spine A number of characteristics set a major divide between the animals/organisms The backbone gives a major division So we have the vertebrate and invertebrate groups  There are familiar names such as; Protozoans (Amoeba, Paramecium) Nematodes (Ascaris) Arthropods (Insects) These are invertebrate types  The invertebrates are a group of organisms/animals lacking a spinal column / backbone Invertebrates are the most abundant organisms They make up about 95% of animal species on earth  Occupying almost all habitats; marine, freshwater, soil, and so on They completely lack cell walls No bony skeleton either internal or external Many possess fluid filled hydrostatic skeleton, others have hard exoskeleton or outer shells  There are no complex skeletal systems (some tends to be slow and small in nature) They are cold blooded (they cannot regulate their own body temperature which invariably depends on the temperature of the atmosphere) Most are motile but few are sedentary  They have largely varied body plan Most are organized with symmetrical body organization (radial, spherical and bilateral) A minority exhibit no symmetry  They are heterotrophs (they cannot make their own food) Typically, there is a digestive chamber with one or two openings to the exterior They possess a nervous system consisting of small number neurons used for conducting nerve impulses Gas exchange is through respiratory system by means of passive diffusion or active ventilation  Many invertebrates use gills as a major means of gas exchange Most invertebrates reproduce at least partly through, sexual reproduction There is fusion of a smaller motile spermatozoa or large non-motile ova to produce a zygote, which develops into a new individual Others undergo asexual reproduction or sometimes exhibit both sexual and asexual types.  The invertebrates constitute an artificial division of the animal kingdom Some members are closely related to the vertebrates than to other invertebrates They do not possess skeleton of bone  Swedish botanist Carolus (Carl) Linnaeus(1707- 1778) developed the modern taxonomic system There are 8 ranks on the basis of certain relationships between organisms Domain, the highest order and the broadest category was recently added to the hierarchy of groups The species is the lowest order and most natural group  Based on the differences between eukaryotic and prokaryotic cell types, domain can be classified into 3 broad categories:  Archea (Archeabacteria): these are bacteria that live in extreme environment Eubacteria: these bacteria are found in everyday life Eukarya: it comprises almost all the world’s visible living things The 3 domains are categorized into 5 kingdoms: i. Monera- comprises the unicellular organisms ii. Protista- unicellular like Monera, but more complex, more developed, contains nucleus iii.Plantae- all plants (algae to the largest such as Pine, Eucalyptus) iv. Fungi- eukaryotic organisms made up of microorganisms such as yeast, molds and mushrooms, basically parasites v. Animalia- includes all the multicellular and eukaryotic organisms (of animal group). Also known as Metazoan  The animal kingdom is informally divided into invertebrates and vertebrates  Course Outline There are close to 2 million species of animals with diversity in structure, form and size: Classification of the invertebrates Characteristics and life history of representative types from each phylum Medical, veterinary and agricultural importance of familiar and important invertebrates.  General classification of invertebrates All living things are placed into groups depending on common characteristics, that is, they are classified based on their similar and dissimilar structures Approximately, 2 million species of animals with diversity in structure, form and size have been described.  Grouping of the large array of animals into hierarchical level = classification Also referred to as taxa (singular = taxon)  The technique of classifying organisms is known as Taxonomy Derived from words Taxis (meaning arrangements) and Nomos (meaning method)  Organisms are arranged in an ascending order Forming series of groups of increasing inclusiveness This reveals the phylogenetic affinities of different animal taxa  The taxonomists may subdivide or group together the 8 levels/taxa. Today 36 taxonomic ranks or animal phyla are recognised. Classification could be based on : embryological and anatomical features, cellular levels, grades of organisation and evolutionary basis.  Based on embryological and anatomical characters that reveal phylogenetic affinities of different animal. There can then be supertaxa, subtaxa and infrataxa The most natural group is the species. It is the lowest in the Linean system of classification  The system of naming (biological nomenclature) is based on the binomial nomenclature. Each organism, despite the large diversity within the group has two latin names; the generic and specific The Genus is written with an initial capital letter while the species has an initial lower case letter, both underlined or written in italics  Examples: Entamoeba histolytica (E. histolytica) Fasciola gigantica (F. gigantica) Entamoeba histolytica (E. histolytica) Fasciola gigantica (F. gigantica)  Until the late 1800s, living organisms were traditionally placed in either of two kingdoms  Kingdom Plant Animal  Single cell (unicellular) organisms were arbitrarily assigned by the zoologists and botanists Hence, some organisms were placed in both kingdoms depending on who is doing the grouping  Example: Euglena: motile like animals Possesses chlorophyll and photosynthesize like plant  Basic biological organization is based on- A common ancestry of animals The basic cellular composition The mode of nutrition (possibly) On cellular level of organization, two subkingdoms are recognized  Kingdom Subkingdom Subkingdom Protozoa Metazoa (unicellular) (multicellular) Protozoan group Simplest-animal-like complete organisms Able to carry out all the basic functions of life carried out by the more complex animals Metazoan group Exhibit structural complexity Cells form aggregate units which perform specialized functions Grouping or subdivision was according to various methods of organization 5 grades of organization with increasing complexity were recognized Essentially, there are limited body plan shared by the diversed animal forms Protoplasmic Cellular Tissue Organ Organ system  PROTOPLASMIC All life activities are confined within a single cell Protoplasm is differentiated into organelles Organelles perform specialized functions  CELLULAR Aggregation of cells These are functionally differentiated  TISSUE Aggregation of similar cells into definite layers to form tissues ORGAN Aggregation of tissues into organs  ORGAN SYSTEM Organs work together to perform functions like circulation, respiration, reproduction, digestion and so on  Grouping on evolutionary basis; two distinct lines evolved from the first or earlier cell forms Hence, all living organisms fall into two major groups  Organisms Eukaryotes Prokaryotes (No (Nuclear envelopes nuclear envelope encloses the enclosing the nucleus) nuclear material  Eukaryotes and prokaryotes are 2 fundamental categories Prokaryotes Eukaryotes Smallest and simplest type Complex in structure of cells No true membrane and no they have nuclei and membrane bound organelles membrane bound organelles Genome consist of single Genome consist of numerous Chromosome chromosome Reproduction is asexual, Reproduction is sexual; by basically mitosis type mitosis and meiosis  A 5 kingdom system of classification was proposed in 1969 incorporating: I. The basic prokaryote –eukaryote distinction II. The mode of nutrition of the multicellular organisms 5 kingdom classification Kingdom Monera (Prokaryotes - the bacteria) Kingdom Protista (Algae, Protozoa, Slime mould, Oomycota) Kingdom Fungi (fungi) Kingdom Plantae (Plants) Kingdom Animalia (Animals)  All organisms apart from members of the Monera are eukaryotes Metazoan group is divided into 3 branches  A – Mesozoa: Phylum Mesozoa Phylum Porifera B – Parazoa Phylum Placozoa All other phyla C – Eumetazoa  Eumetazoa is divided into 2 grades; Phylum Cnidaria Radiata Eumetazoa Phylum Ctenophora Bilateria  Bilateria is made up of 2 divisions; Based on the location of the mouth and anus in relation to the blastopore  Protostomia Bilateria Deuterostomia  Further grouping of animals is based on the presence of a false/ true body cavity or lack of a true body cavity, i.e. Pseudocoelom/ Coelom or Acoelom  Acoelomate-----1. Phylum Platyhelminthes 2. Phylum Nemertea 3. Phylum Gnathostomulida  Pseudocoelomate: (9 Phyla) 1. Phylum Rotifera 2. Phylum Gastrotrichia 3. Phylum Kinorhycha 4. Phylum Loricifera 5. Phylum Priapulida 6. Phylum Nematoda 7. Phylum Nematomorpha 8. Phylum Acanthocephala 9. Phylum Entoprocta  Eucoelomate ----------- 1. Phylum Mollusca (3 Phyla) 2. Phylum Annelida 3. Phylum Arthropoda  6 phyla of lesser protostomes 3 phyla of lophophorate animals These lack significant economic and ecological importance  Phylum Echinodermata (Deuterostomia) Phylum Chaetognatha (Protostomia) Phylum Hemichordata (Deuterostomia) Unicellular Eukaryotes: The Protista DOMAIN OF LIFE  The first evidence for life on earth dates from approximately 3.5 billion years ago and were prokaryotes (Bacteria and Archaea) whose descendants diversified greatly over an enormous time span. The common ancestor of eukaryotes was formed by merging cells through symbiogenesis  Mitochondrion capable of deriving energy from carbon compounds using oxygen originated from engulfed alpha- proteobacterium through primary endosymbiosis. While plastids capable of photosynthesis originated from an engulfed cyanobacterium  Eukaryotes are organisms with nucleus and other membrane enclosed organelles such as mitochondria and Golgi apparatus. Eukaryotic cells also have a well developed cytoskeleton that provides the structural support that enables them to have asymmetric (irregular) forms as well as change shape when they feed, move and grow.  Unicellular eukaryotes is a complete organism in which all life’s activities occur within the limits of a single plasma membrane The most numerous and diverse eukaryotes are the protists which are mostly single-celled organisms. Any eukaryote that is not a fungus, plant or animal is classified as Protista  With few exceptions, modern eukaryotic cells possess the energy-producing organelles termed mitochondria, and photosynthetic eukaryotic cells possess chloroplasts, the energy harvesting organelles. Mitochondria and chloroplasts are both believed to have entered early eukaryotic cells by a process called endosymbiosis Diversity of protists stems from endosymbiosis. Mitochondria descended from proteobacteria, a purple sulfur bacteria and a relatives of parasitic Rickettsia that were incorporated into eukaryotic cells early in the history of the group  While Chloroplasts are derived from cyanobacteria The large number of eukaryotes that do not fit into any of the three eukaryotic kingdoms are arbitrarily grouped into a single kingdom called Protista Some protist are more closely related to plants, fungi or animals than they are to other protist  FEATURES OF PROTISTA Eukaryotic; presence of nucleus and membrane-bound organelles. Mostly single celled or exist as group of similar cells. Some have animal-like cells (no cell wall) wrongly grouped together as phylum protozoa. Others have plant-like cells (with cellulose cell walls and chloroplasts)  Unicellular protists carry out essential life function using subcellular organelles. Certain protists rely on organelles not found in most other eukaryotes, eg the contractile vacuoles that pump excess water from the cell. Ocelloid with component resembling lens and retina is an eye-like organelle in the dinoflagellates  Often, they are more complex than any particular cell in higher organisms. Some protists form colonies yet independent on one another for most functions. Some colonies can become complex, yet their level of organization is at protoplasmic grade.  Assemblage of eukaryotic unicellular organisms was initially called protozoa. Protists represent all symmetries and exhibit all types of nutrition Some protists are plantlike because they are primarily autotrophic Others are animal-like because they are primarily heterotrophic Yet others combine autotrophy and heterotrophy in a new mode called mixotrophy  Heterotrophic may involve ingesting food in a soluble form (osmotrophs or saprozoic) or in a particulate form (phagotrophs or holozoic feeders). Autotrophic protists are either photosynthetic or chemoautotrophic In a typical protist regular arrangement of microtubules, called the pellicle, underlies the plasma membrane of many protista. The pellicle is rigid enough to maintain the shape of the cell, but it is also flexible cytostome A PROTIST  The Cytoplasm is not homogeneous; sometimes peripheral and central areas can be distinguished as: Ectoplasm is more transparent (hyaline) by light microscopy, and it bears the bases of the cilia or flagella Endoplasm appears more granular and contains the nucleus and cytoplasmic organelles  Water enters freshwater cells with higher solute concentrations by osmosis. Contractile vacuoles remove this excess water Some protists ingest food through a specialized region cytostome and cytopharynx, analogous to a mouth. Phagotrophic heterotrophs ingest visible particles of food by pulling them into intracellular vesicles called food vacuoles or phagosomes  Lysosomes fuse with food vacuoles that form during endocytosis to introduce enzymes that digest the food particles. After digestion is complete, the egestion vacuoles release their waste contents by exocytosis at a specialized region of the plasma membrane or pellicle called the cytopyge.  REPRODUCTION Protista reproduce both sexually and asexually One of the simplest and most common forms of asexual reproduction is binary fission. Here the nuclear membrane persist throughout mitosis with the microtubular spindle forming within it  Longitudinal binary fission in euglenoids Longitudinal binary fission in the Euglena begins with mitosis and then cytoplasmic division (cytokinesis) divides the organelles b/w the two cells and results in two similarly sized organism. Nuclear envelope remain intact during mitosis Transverse binary fission in ciliates  Budding is another form of asexual reproduction in which mitosis is followed by the incorporation of one nucleus into a cytoplasmic mass that is much smaller than the parent cell. In Schizogony or multiple fission cell division preceded by several nuclear division This allows cytokinesis to produce several daughter cells almost simultaneously.  Most eukaryotes undergo Sexual reproduction. Meosis allows for the production of haploid cells, the gametes, and the subsequent fusion of gametes to form a zygote. In some protists, the sexually mature individual is haploid. Gametes in these case are produced by mitosis, and meiosis follows the union of the gametes.  LOCOMOTION Several means of locomotion: Some wave one or more flagella to propel them through water Others use banks of short flagella-like structure called cilia to create water current for movement and feeding, Pseudopods are the chief means of locomotion among the amoebas Yet in other protists move by means of undulating their plasma membrane.  Eukaryotic flagella are extensions of the cytoplasm, consisting of bundles of microtubules covered by the cell’s plasma membrane. They are quite different from prokaryotic flagella, which are filaments composed of globular proteins attached to the cell surface. There is no real morphological distinction between cilia and flagella Means of locomotion used in old classifications Originally, the means of locomotion was used to distinguish unicellular eukaryotes: Flagellates use flagella Ciliates travel via a ciliated body surface Amebas extend their pseudopodia to move Protists constitute such an unnatural group and therefore using locomotory structures leads to chaotic grouping of genetically unrelated organisms. A cross section through a Flagellum  Outward extension of the cytoskeleton and cytoplasm forms the pseudopodia used for movement and feeding in Amoebas Lobopodia are blunt and broad cell processes containing ectoplasm and endoplasm  Filopodia are thread-like and contain ectoplasm only Reticulopodia are net-like series of cell extensions Axopodia are thin filamentous cell extension supported by a central axis of microtubules  Recent classification using metagenomic studies grouped the protists according to their phylogenetic relatedness. Microsporidians once considered amitochondriate protists are now classified as fungi Comparison of the features of the six kingdoms Eukaryotic evolutionary relationships  Supergroup EXCAVATA The Diplomonads, Parabasalids and Euglenozoans are genetically related and grouped under a supergroup EXCAVATA based cytostkeletal and DNA sequence , and the presence of excavated feeding groove on one side of the cell body Excavata has a posteriorly directed flagellum which generate feeding current  Two major clades (the parabasalids and diplomonads) have two nuclei, multiple flagella and modified mitochondria; Members of the third clade (the euglenozoans) have flagella that differ in structure from those of other organisms and several have acquired chloroplasts through endosymbiosis. Excavates include parasites as well as many predatory and photosynthetic species.  Diplomonads Giardia intestinalis placed under Diplomonads based on modified mitochondria called mitosomes Mitosomes lack functional electron transport chains and hence get the energy they need from anaerobic pathway  Other features include possession of multiple posterior flagella and two haploid nuclei per cell. G. intestinalis lacks the characteristic surface groove of the Excavata and inhabits the intestines of mammals. It can infect people when they drink water contaminated with feces containing Giardia cysts which can cause severe diarrhea. Boiling the water kills the parasite. Giardia intestinalis  Parabasalids Distinguishing feature is the possession of undulating membrane used in locomotion in addition to flagella also used in propelling themselves. They have one nucleus per cell and reduced mitochondria called hydrogenosome that generate energy anaerobically releasing hydrogen gas. Some live symbiotically in guts of termites and cockroaches where they digest cellulose in their wood-based diet.  The best-known parabasalid is Trichomonas vaginalis, a sexually transmitted trichomoniasis that infects about 140 million people each year worldwide. T. vaginalis travels along the mucus coated lining of the human reproductive and urinary tracts by moving its flagella and by undulating part of its plasma membrane. In females, if the vagina’s normal acidity is disturbed, T. vaginalis can outcompete beneficial microorganisms there and infect the vagina. Trichomonas vaginalis  Euglenozoa Euglenozoans belong to a diverse clade that includes predatory heterotrophs, photosynthetic autotrophs, mixotrophs, and parasites illustrating the impossibility of distinguishing plant-like and animal-like protists. The main morphological feature that distinguishes Euglenozoa is the presence of a rod with either a spiral or a crystalline structure inside each of their flagella. Their body shape change while swimming alternating b/w being stretched out and rounded up  Two monophyletic subphyla Euglenida and Kinetoplasta Euglenida: has a pocket/reservior at one end of the cell from which one or two flagella emerge One third have chloroplast and autotrophic others lack chloroplast and are hertertrophic Some euglenids are mixotrophs: They perform photosynthesis when sunlight is available, and become heterotrophic absorbing organic nutrients from their environment in absence of sunlight. Many other euglenids engulf prey by phagocytosis Euglena viridis  Kinetoplasta Kinetoplastids have a single, large mitochondrion that contains an organized mass of DNA called a kinetoplast. These protists include species that feed on prokaryotes in freshwater, marine, and moist terrestrial ecosystems, as well as species that parasitize animals, plants, and other protists. Eg, Trypanosoma brucei that infect humans and cause sleeping sickness  This neurological disease currently afflicts about 10,000 people each year, mostly in rural areas of Africa. Where the infection occurs through the bite of a vector tsetse fly (Glossina spp.). Trypanosoma cruzi is another trypanosome that causes American trypanosmiasis or Chagas’ disease in humans in Central America and South America. It is transmitted by “kissing bugs” (Triatominae) Acute Chagas’ disease is most commonly severe among children less than five years old.  Two to 3 million people in South and Central America show chronic Chagas’ disease, and 45,000 of these die each year. Other parasitic Kinetoplastids include several species of Leishmania cause different types of leishmaniasis in humans. Leishmaniasis are transmitted by sand flies (Phlebotomus and Luzomyia) in Africa and Asia, and Central America and South America. SUPERGROUP CHROMALVEOLATA  The stramenopiles and alveolates form a monophyletic supergroup based on whole- genome DNA sequence analyses. It was suggested that stramenopiles and alveolates, originated when a common ancestor of these two clades engulfed a single-celled, photosynthetic red alga. Because red algae are thought to have originated by primary endosymbiosis such an origin for the stramenopiles and alveolates is referred to as secondary endosymbiosis.  ALVEOLATA Members of this subgroup have membrane- bound sacs (alveoli) beneath the plasma membrane In the Ciliophora, the alveoli produce pellicles; In the Dinoflagellata, the alveoli produce thecal plates; In the Apicomplexa, the alveoli have structural functions  DINOFLAGELLATA Approximately half of the dinoflagellates species are photoautotrophic. The rest are colorless and heterotrophic Ancestral dinoflagellates probably were heterotrophic, and some acquired chloroplasts through secondary endosymbiosis from algal sources Many are mixotrophic  FEATURES: They commonly have two flagella, one equatorial and one longitudinal, each borne at least partially in grooves called the sulcus which it uses for spinning through water. The body may be naked or covered by cellulose plates or valves Ceratium for example, has a thick covering with long spines, into which the body extends  Many of the living species of photosynthetic dinoflagellates are also heterotrophic to some extent, and some with functional chloroplasts can switch entirely to heterotrophy in the absence of sufficient light some species are among the most important primary producers in marine environments The feeding mechanisms of heterotrophic dinoflagellates are quite diverse while some heterotrophs feed by saprotrophy, other dinoflagellates ingest food particles by phagocytosis.  Many species can ingest prey through a permanent cell mouth between the plates near the posterior area of the body The cytostome is supported by sheets of microtubules Ceratium can catch food with posterior pseudopodia and ingest it between the flexible plates in the posterior groove.  Many, in fact, are voracious predators that ingest other protists and microinvertebrates or use specialized cellular appendages to pierce prey and suck out their cytoplasmic contents. Noctiluca, a colorless dinoflagellate, is a voracious predator and has a long, motile tentacle, near the base of which its single, short flagellum emerges. Noctiluca is one of many marine organisms that can produce light (bioluminescence).  Parasitic dinoflagellates have a broad range of hosts, morphological diversity, and life histories. The genus Haplozoon is a small group of intestinal parasites occurring in marine worms. Haplozoon have long been viewed as "multicellular" or "colonial“ in their organization. However, recent studies revealed a unique cellular organization in which the entire organism is bounded by a single continuous membrane, suggesting syncytial composition of cell-like compartments separated by sheets of alveoli.  Dinoflagellate bloom called red tide make coastal waters brownish red or pink The colour is as a result of carotenoids in the pastids However, any instance of a bloom producing detectable levels of toxic substances is now called a red tide Dinoflagellates such Gymnodinium produce toxin that can cause massive fish kill Consuption of tainted mollusc or fish affects humans sometimes fatally  The water may be red, brown, yellow, or not remarkably colored at all. The toxins do not harm the dinoflagellates, but if they are present in high concentrations they can harm fish or other marine life. In area where clams, mussels, oysters or other filter-feeders are harvested for human consumption, the beach will be closed during a red tide. Closure will last until the filter-feeders have digested all the dinoflagellate toxin that they consumed Red Tide  CILIOPHORA FEATURES Cilia often cover the entire cell or may be clustered in a few rows or tufts Some ciliates lack cilia as adults, although cilia occur at other stages in the life cycle Cilia used for swimming and feeding arise from subsurface basal granules Cilia are identical to flagella. Major difference is in the number  Cilia may cover the surface of the organism or may be restricted to the oral region or to certain bands. In some forms cilia are fused into a sheet called an undulating membrane or into smaller membranelles, both used to propel food into the cytopharynx Cilia may be fused forming stiffened tufts called cirri, often used in locomotion by the creeping ciliates  Possess two type of nuclei: micro and macronucleus A cell has one or more of nuclei of each type Possesses Large contractile vacuole Complex organelles mostly as part of the pellicle  Shape maintained by the complex pellicle Ciliates possess distinct anterior Food is ingested through the cytostome and cytopharynx Food digestion occurs within the food vacuole Contractile vacuoles provide for water balance Paramecium a Ciliophoran  Micronuclei is for exchange of genetic information during conjugation Macronuclei is required for producing RNAs and Proteins for daily functions During asexual reproduction by binary fission macronucleus divide into two pieces and new gullet and two new contractile vacuoles appear BINARY FISSION IN CILIOPHORA  Conjugation is the temporary union of two individuals to exchange chromosomal material During conjugation the haploid micronuclei resulting from meiotic division function as gametes During the union the macronucleus disintegrates and the micronucleus of each individual undergoes meiosis, giving rise to four haploid micronuclei, three of which degenerate CONJUGATION IN CILIOPHORA  The remaining micronucleus then divides into two haploid pronuclei, one of which is exchanged with the other conjugant. The pronuclei fuse to restore the diploid number of chromosomes Sexual reproduction permits gene recombinations, thus increasing genetic variation in the population Thus the exconjugants contains hereditary material from two individuals.  Most ciliates are free-living in freshwater or marine habitats, but commensal and parasitic forms do occur The free-living Ciliates may be predatory or suspension feeders while symbiotic may be commensal and parasitic and live within the vertebrate gut. Balantidium coli is a common parasite of man, lower primates and hogs  Usually the organisms are not pathogenic, but in humans they sometimes invade the intestinal lining. Infections result from fecal contamination of food Pathogenesis is similar to that of E. histolitica. Ichthyophthirus multifillis is a ciliate fish parasite APICOMPLEXA  Almost all apicomplexans are endoparasitic Lack visible means of locomotion although Pseudopodia occur in some intracellular stages, and gametes of some species are flagellated. The presence of a certain combination of organelles, the apical complex, distinguishes this clade Apical complex is usually for penetrating host cell  The apicoplast, a modified plastid, may be ringlike, tubular or filamentous Mostly intracellular Uninucleated Form spores (sporozoites) at some stage in their life cycle  Parasites of vertebrates and invertebrates which cause serious disease of domestic animals and humans. It has a very complex life cycle that comprise of asexual (schizogony, sporogony) and sexual (gametagamy) phases that require two host E.G. Cryptosporidium, Toxoplasma, Plasmodium, Babesia, Isospora, Cyclospora Life cycle of Plasmodium  Crytoporidium is another Apicomplexan protozoa that causes chronic diarrhea in immunosuppressed individuals Toxoplasmosis caused by Toxoplasma results when meat containing encysted merozoites are eaten raw or poorly cooked And when oocyst are ingested with food contaminated by cat feces  Most Toxoplasmosis infections are asymptomatic In pregnancy congenital toxoplasmosis may develop: – Stillbirths – Spontaneous abortions Surviving fetuses show signs of mental retardation and epileptic seizures.  Coccidiosis is generally applied only to infections with Eimeria or Isospora. Humans can be infected with species of Isospora, but there is usually little disease. However, Isospora infections can be very serious in AIDS patients. Some species of Eimeria may cause serious disease in some domestic animals. Symptoms usually include severe diarrhea or dysentery  Sporogony Sporozoite  Domian EUKARYOTA Superphylum ALVEOLATA Phylum APICOMPLEXA Class Coccidea Order HAEMOSPORORIDA Family PLASMODIIDAE Genus PLASMODIUM Species falciparum  Stramenopiles Stramenopile refers to their characteristic flagellum, which has numerous fine, hairlike projections In most stramenopiles, the hairy flagellum is paired with a shorter smooth flagellum The cells are surrounded by plasma membrane, which may be supported by silica (silicon dioxide), calcium carbonate or proteinaceous shells, scales, or tests.  Almost all species posses unique, complex, three-part tubular hairs on the flagella at some stage in life cycle. Most exhibit heterokont flagellation (i.e., with two flagella, one directed anteriorly, one directed posteriorly). Sometimes only the reproductive cells are flagellated and the trophic cells lack any obvious mode of locomotion.  Mitochondria have short tubular cristae This clade contains forms that are photosynthetic, others are ingesting heterotrophs, and still others are saprophytic The clade include opalinids, diatom, Oomycetes and brown algae  Opalinata Opalinids, once thought to be modified ciliates are now placed in Stramenopiles. Their inclusion is based primarily on analyses of DNA sequence data Members are commensals in the rectum of frogs & toads Opalinids are thought to have lost their flagellation and replaced with rows of cilia  Almost all are endosymbiotic in the hindgut of anurans where they ingest dissolved material Some opalinids are binucleate, others are multinucleate, but all are homokaryotic or monomorphic Their numerous oblique rows of cilia clearly differ from the rows in ciliates in that they lack the kinetidal system.  There is no cytostome Sexual reproduction is by syngamy and asexual reproduction is by binary fission During asexual reproduction, the fission plane parallels the oblique ciliary rows; thus it is longitudinal (as it is in flagellates) rather than transverse (as it is in ciliates). Opalina ranarum  Nuclei Lines of Endo-plasm cilia Ecto-plasm Cilia Pellicle Opalina ranarum  Diatom Diatom are unicellular algae that have a unique glass-like wall made of silicondioxide embedded in an organic matrix. They are among the most abundant photosynthetic organisms both in the ocean and in lakes They are key components of marine ecosystems and, along with dinoflagellates and coccolithophores, contribute greatly to oceanic primary productivity  Benthic deposits of the siliceous shells of dead marine diatoms can, over geologic time, result in massive uplifted land formations that are n1ined as diatomaceous earth Diatomaceous earth sediments are mined for their quality as a filtering medium and for many other uses. It is estimated that diatom alone account for up to 20% of global carbon fixation  Diatom act as carbon sink thereby playing a great role in ameliorating global warming. Carbon in their bodies remains at the ocean floor for some time, rather than being released immediately as CO2 by decomposers. Because their shells (frustules) are composed of silica, they are also extremely important for the biogeochemicalcycling of silicon  On the other hand a few marine diatoms produce toxins similar in potency to those seen in some dinoflagellates. Diatom have caused deaths of sea lions, seabirds, fish and shellfish. Diatoms in the genus Pseudonitzschia are capable of producing the neurotoxin, domoic acid that can accumulate in the food chain and responsible for neurological disorders and memory loss called amnesic shellfish poisoning, or ASP). Silicious skeleton of Pennate diatom Tubular diatom the centric diatom Navicula sp Aulacosella Actinocyclus sp Diatom  Brown algae Brown algae also known seaweed (kelp) is a multicellular protists which form an integral base to many coastal food webs Algin, extracted from seaweed is used as an emulsifier in many thing from paint to babyfood to cosmetics  Oomycetes Oomycetes include the water molds, the white rusts, downy mildews, the potato blight. Although oomycetes descended from plastid- bearing ancestors, they no longer have plastids and do not perform photosynthesis. Instead, they typically acquire nutrients as decomposers or parasites. Most water molds are decomposers that grow as cottony masses on dead algae and animals  Based on their morphology, these organisms were previously classified as fungi For example, many Oomycetes have multinucleate filaments (hyphae) that resemble fungal hyphae The devastating Irish potato blight disease that resulted in famine of the nineteenth century was caused by an Oomycete, Phytophthera infestans  RHIZARIA Both Rhizarians and Amoebozoans use pseudopods for locomotion. Pseudopods are flowing projections of cytoplasm that extend to pull the organism forward. Amoeboid motion was once used as a trait to group protists, but the inclusion of molecular data in phylogenetic reconstructions led to the realization that locomotion alone was not a useful trait in evolutionary analyses.  Rhizarians are amoebas and flagellated protists that feed using threadlike pseudopodia. Within the Rhizaria, three distinct monophyletic groups have been identified: Radiolaria, Foraminifera and Cercozoa They are usually testate. Some have the test external and multi-chambered. While others have their skeleton internally placed.  Cercozoa The group is heterogeneous in terms of morphology. There are flagellated and ameboid members. Ameboid cercozoans also vary in pseudopodia formed: axopodia are made in phaeodarians and desmothoracids, but other members of the group make filopodia Ameboid members of the group may be naked or testate  Euglypha, is a testate cercozoan which makes a test from collected particles while Clathrulina, makes a siliceous capsule Phaeodarians, have an amorphous silica skeleton with magnesium, calcium, and copper added. Cercozoans are equally heterogeneous in lifestyle. There are photosynthetic members such as the chlorarachniophytes, which are naked green amebas with filopodia.  Other members are free-living heterotrophs, and still others, such as plasmodiophorids and haplosporidians, are parasites. Plasmodiophorids, once thought to be fungi, are obligate intracellular parasites responsible for crop damage. Granuloreticulosea (Foraminifera) Characteristic of the group are pore-studded shells (called tests) composed of organic materials usually reinforced with grains of calcium carbonate, sand, or even plates from shells of echinoderms or spicules from sponge skeletons Foraminiferans secrete many chambered tests made of calcium carbonate, although they sometimes accumulate silica, silt, and other foreign materials  The individual chambers of these tests are often demarcated from each other by perforated septa. Thin, extensively branching pseudopodia called reticulopodia, project from minute openings in the test, forming dense pseudopodial networks used primarily for food capture.  Repeated extension and shortening of the pseudopodia also permit slow crawling over the ocean bottom. Foraminiferans feed on a remarkable variety of food, including other protists, small metazoans, fungi, bacteria, and organic detritus. In addition, some species house photosynthesizing symbionts, including dinoflagellates, Polystomella strigillata Cibicides labatulus  Others can take up dissolved organic material from seawater Most foraminiferans live on the ocean floor in incredible numbers Dead foraminiferans have been sinking to the bottom of the ocean, building up a characteristic ooze rich in lime and silica  Of practical importance are the limestone and chalk deposits that were laid down by the accumulation of foraminiferans when sea covered what is now land. Since fossil foraminiferans can be found in well drillings, certain foraminiferan fossils are used as fairly reliable indicators of likely places to drill for oil  Radiolaria Radiolarians are marine testate amebas with axopodia (pseudopodia with thin, radiating microtubules that give a spiny, rayed appearance to many species) All radiozoans possess a rigid endoskeleton composed either of silica (in radiolarians) or strontium sulfate (in acantharians) All radiolarians and most acantharians are planktonic, passively carried about by ocean currents (planktonic).  Many species possess symbiotic algae getting some of their nutritional requirements through photosynthesis. They also feed as carnivores, capturing microscopic prey with the cytoplasm that flows along their axopods. The radiolarian body is generally spherical and divided into an intracapsular zone and an extracapsular zone by a perforated, spherical membrane or capsule.  Food vacuole formation and digestion occur in the extracapsular region. Because of their siliceous skeletons, radiolarians are prominent in the fossil record In contrast, acantharians have left no fossil record, as the strontium sulfate supports degrade soon after the organism dies. Radiolarian Actinosphaerium sol Unikonta  Amoebozoa The clade includes many species of amoebas that have lobe- or tube-shaped pseudopodia (Lobopodia) rather than the threadlike pseudopodia found in rhizarians. Most amoeba are free-living, but some are parasitic. Amoebozoans include tubulinids, slime molds, and entamoebas.  Tubulinea Large and varied group of amoebozoans that have lobe- or tube-shaped pseudopodia. These unicellular protists are ubiquitous in soil as well as freshwater and marine environments. Most are heterotrophs that actively seek and engulf bacteria and other protists by phagocytosis; e.g Amoeba proteus, Some tubulinids also feed on detritus  Some members referred to as naked amoebas lack a test (shell) or other supporting structures Others possess test which may be calcareous, proteineous, siliceous or chitinous. Other test may compose of sand and debris cemented into a secreted matrix  Large opening in the shell permit extension of the body and pseudopodia Testate amebas with lobose pseudopodia, include Arcella and Diffligia while naked lobose amebas, include Chaos carolinense, Amoeba proteus, and members of genus Acanthamoeba Amoeba proteus Difflugia oblongata  Growth & multiplication is by binary fission involving nuclear division by mitosis followed by cytoplasmic division Binary fission occurs when an aboeba reaches a certain size limit Triggered off when the surface area : volume ratio and / or when cytoplasmic volume : nuclear volume ratio reach a limit.  Under unfavourable conditions Amoeba forms cyst & remain inactive , until moisture or warm temperature are restored There may be sporulation in other species like Entamoeba histolytica which undergo spore formation No sexual reproduction is known to occur  Entamoebida Whereas most amoebozoans are free-living, those that belong to the genus Entamoeba are symbiotic parasites. They infect all classes of vertebrate animals as well as some invertebrates. Humans are host to at least six species of Entamoeba.  While Entamoeba coli is a commensal species that feed on bacteria and intestinal debris, E. histolytica, is known to be pathogenic. Both leave as cyst in feces and reinfection is via the mouth E. histolytica causes amoebic dysentery and is spread via contaminated drinking water, food, or eating utensils.  It causes inflammation and ulceration of the lower intestinal tract and a debilitating diarrhea that includes blood and mucus characterize dysentery Amoebic dysentery is responsible for up to 110,000 deaths worldwide every year, being the third leading cause of death.  Acanthamoebida Acanthamoeba possess both flagellated and amoeboid form and are facultative parasites of humans. Acanthamoeba causes meninggoencephalitis while Naegleria fowleri infects the cornea leading to inflammation and opacity  Mycetozoa(Slime molds) Once were thought to be fungi because they produce fruiting bodies that aid in spore dispersal. Through DNA sequence analyses that resemblance is a case of evolutionary convergence. Slime molds have diverged into two main branches;  Plasmodial Slime Molds Brightly coloured (yellow or orange) As they grow, they form a mass called a plasmodium, which can be many centimeters in diameter. Despite its size, but a single mass of cytoplasm that is undivided by plasma membranes and that contains many nuclei. The “supercell” is the product of mitotic nuclear divisions that are not followed by cytokinesis.  The plasmodium extends pseudopodia through moist soil, leaf mulch, or rotting logs, engulfing food particles by phagocytosis as it grows. If the habitat dries up or there is no food left, the plasmodium stops growing and differentiates into fruiting bodies that function in sexual reproduction.  Cellular Slime Molds The cellular slime molds have intriguing life cycle. The feeding stage of these organisms consists of solitary cells that function individually. However when food is depleted, the cells form a slug-like aggregate that functions as a unit. Unlike the feeding stage (plasmodium), these aggregated cells remain separated by their individual plasma membranes. Ultimately, the aggregated cells form an asexual fruiting body Life cycle of cellular slime mold SAR  References Invertebrates--- R. C. BRUSCA, W. MOORE, S. M. SHUSTER, Intergrated Principles of Zoology.---- Hickman, Roberts & Larson PHYLUM PORIFERA SPONGES, PORE-BEARERS  Sponge is one of the simple metazoan They lack nerves and true musculature There is no specialized reproductive, respiratory, sensory or excretory organs 98% of the 15000 extant spp are marine while the 2% are found in freshwater.  Sponges are often amorphous, asymmetrical creatures Being asymmetrical, there is no side referred to as anterior, posterior or oral surfaces  Only a few different types of cells are encountered These cells are functionally independent Dissociated cells can dedifferentiate to amoeboid form, re-aggregate and redeferentiate to reform a sponge  Sponge is a rigid perforated bag Body wall compose of outer epithelial-like pinacoderm made of pinacocytes The mesohyl containing amoebocytes and supporting elements Inner surface surrounding the spongocoel is lined by choanocytes SPONGE MORPHOLOGY  The pinacocytes also line the incurrent canals and spongocoel where choanocytes is lacking Pinacocytes contraction can vary the diameter of the ostia It also lead minor or major shape change in sponge BODY WALL OF SPONGE  Choanocytes flagella beating sucks water into the spogocoel through the ostia and expels it through the osculum Ostia are always numerous but there may be only one osculum. Porocytes that extend through the body wall form ostia. Filter feeders on Suspended organic particles using the microvilli of the Choanocytes as the final filter  Choanocytes perform the following functions: Generate current that help circulate the sea water within and through the sponge Capture food particles Capture incoming sperm for fertilization  Water current passing through sponge perform the following functions: Sources of food particles System of gas exchange Removal of waste Gamete transfer  The gelatinous mesohyl layer though acellular and non-living contains : Amoeboid archaeocytes Supporting elements  Functions of the archaeocytes: Intracellular food digestion Store digested food materials Give rise to both male and female gametes Active role in non-self recognition Elimination of wastes Secrete supporting elements Supporting elements Calcareous or silicious spicules Spongin Respectively secreted by sclerocytes and spogocytes Defenses is usually chemical, but spicules may discourage predation Regeration and Reproduction Sponge exhibit remarkable power of regeneration Asexual reproduction by gemmule formation and regression Gemmule is composed of archaeocytes cluster surrounded by capsule Gemmule is resistant to: Desiccation Freezing Oxygen lack Sponge Gemmule  Sexual reproduction is by gamete formation in the mesohyl Sperm exit the sponge through the osculum Embryonic development leads to formation of: Flagellated parenchymula larvae Amphiblastula larvae Poriferan Diversity  In Asconoid the spongocoel is lined by choanocytes The ostia is represented by with intracellular canal Water enters directly through the ostia into the central spongocoel and leave through the osculum E.g. Leucosolenia  Asconoid imposes limitation on size The problem is solved by repeated folding of the flagellated layer to increase the surface area In syconoids the flagellated layer is evaginated at regular intervals into finger-like projections radial canals  Corresponding invaginations are called incurrent canals Pores (ostia) are located between the incurrent and flagellated canals The flagellated canals sycon sponge open into a central spongocoel E.g Scypha  Falgellated layer is increased in Leuconoid sponge by formation of many small chambers Water that enters dermal pore (ostia) passes a system of incurrent canals into the flagellated chambers Many leuconoids have no atrium Water leaves the body through converging excurrent canals which opens at the osculum  Many leuconoids are irregular with many oscula on the body surface Increase in size in the leuconoid sponge comes with addition of large numbers of flagellated chambers Therefore leuconoid sponge attain the greatest size. E.g Spongilla  Classification Type, composition and morphology of the supporting elements is used in the classification sponges Four classes are recognizes: CALCAREA (Calcareous sponges) Spicules are usually separate and composed of calcium carbonate e.g Sycon, Leucosolenia  HEXACTINELLIDA (Glass Sponge) Spicules are siliceous and always include a six point spicule. Some spicules usually fuse to form long strand and highly organized skeleton. E.g. Euplectella  DEMOSPONGIAE Contains the greatest majority of sponges Skeleton composed of separate siliceous spicules Some possess skeleton of sponging Other members possess both spongin fibers and siliceous spicules  Body form is always leuconoid with irregular symmetry and many oscula E.g. Haliclona, Verongia, Cliona, Spongilla  SCLEROSPONGIA Small group of tropical sponges with siliceous spicules and sponging fibers They are encased within or resting on a solid external skeleton of calcium carbonate Body form is always leuconoid CNIDARIA  DIAGNISTIC FEATURES Radially symmetrical which allows food capturing from all sides. However, there may be modifications. They are diploblastic; the epidermis and gastrodermis are separated by jelly-like mesoglea There is a single gastrovascular cavity that opens only through the mouth. There is no anus.  There is no head, brain and CNS. It has a simple nervous system of interconnecting nerve cell which form nerve net. Statocysts and oceli are usually the only sense organs. The skeletal system may be horny or calcerous, internal or external or continuous. There is no special structures for respiration, excretion and transport system (except sea water channels in some large jelly fish.  Possession of a unique stinging or adhesive structure called cnidae which risides in a cell called cnidocyte. The most common cnidae are called nematocyst.  They usually exhibit polymorphism. Existing either as a solitary or colonial sessile polyp or free floating medusa.  Most polypoid hyrozoans are colonial and polymorphic eg Obelia. Obelia Pedal disc or physa stalk or Stolon in colonial form  Commonly form colonies by asexual reproduction which help them to attend forms and sizes unattainable by a single individual.  Four CLASSES are recognized: Hydrzoa, Scyphozoa, Cubozoa and Anthozoa HYDROZOA The enteron is not divided up by mesenteries The tentacles of the polyp are usually solid The mesoglea is acellular Polypoid Hydra Hydra capturing water flea Very long pendant manubrium of a hydromedusa  Cnidocytes are only found in epidermis Skeleton is external and usually chitinous Hydromedusa are small and are the gamete producing individuals The gametes are ectodermal Craspedote  Ex-umbrallar surface Sub-umbrallar surface Medusa Hydra viridis  HYDROZOA HYDROIDA – GYMNOBLASTEA Hydra, Bougainvilla, Hydractinia,Calycopsis, Turbularia – Calyptoblastea Gonionemus, Obelia, Plumularia, Lovenella TRACHYLINA Polypodium, cunina, Myxidium SIPHONOPHORA Physalia, Eudoxoides, Apolemia CHONDROPHORA Velella, Porpita ACTINULIDA Halammohydra, Otohydra  Scyphozoa Medusa is usually the dominant form. Unlike hydromedusa, scyphomedusa lack velum acraspedote The margin of medusa is fringed by short tentacles and is divided by notches  The mesoglea contains amoeboid mesenchyme cells Cnidocytes occur in the gastrodermis as well as the epidermis Gametes are gastrodermal in origin CUBOZOA(BOX JELLY)  Medusa is square shaped with a marginal self or velum and have a tentacle or group of tentacles which hang from each corners of the square. They are strong swimmers and voracious predators of fish which relates to the elaborate image forming eyes with which they can maneuver obstacles. The stings of some species (eg. Chironex) can be lethal to humans.  ANTHOZOA(SEA ANEMONES AND CORAL) Only the polyp with limited mobility predominates. The oral end is expanded into an oral disc bearing hollow tentacles surrounding the slit-like mouth The gastrovascular cavity is divided into compartments by complete or incomplete mesenteries  Mesenteries bears cnidocytes and gonads The mesoglea contains amoeboid mesenchyme cells The mouth leads into a pharynx At one or both end of the mouth is a siphonoglyph which move water into the gastrovascular cavity Reef forming Anthozoa polyps  CTENOPHORA COMB JELLY, SEA WALNUT SEA GOOSE, SEA BERRY Comb jellies are biradial symmetrical transparent, fragile, acoelomate luminescent marine animal The outer surface bear eight meridonal bands of cilia that resemble comb between the oral and aboral poles. Stotocyst coordinated beating of the cilia move the animal through water Mnemiopsis  Comb jellies are the largest animals that move by means of cilia. They have gelatinous mesenchyme from which the musculature is formed. Monomorphic and without any kind of an attached sessile life stage. Pleurobrachia  Most are hermaphroditic, typically with a characteristic cydippid larval stage They have complete gut. The gut has pharynx which leads to a branching gastrovascular canal system that ends in two small anal pores. They do not have stinging nematocyst, however, the tentacles are equipped with adhesive glue cells called colloblast.  The colloblast releases sticky thread that traps prey that comes in contact with the tentacle Ingestion occurs as the tentacles are wipe across the mouth.  SIMILARITY WITH THE CNIDARIA Radial symmetry Possession of feeding tentacle Gelatinous medusa-like form Acoelomate Presence of relatively simple nervous system consisting of nerve net.  DISTINCTION FROM CNIDARIA No stinging nematocysts Have mouth for food intake and two anal pores for egestion of water and waste at the other end. Monomorphic throughout their life history Never colonial They have wholly mesenchymal musculature (perhaps mesodermal)  PLATYHELMINTHES The flatworms are free-living or parasitic dorsoventrally flattened acoelomate worms  Specific Features Acoelomate-They do not have body cavity outside the enteron No blood vascular and respiratory systems Possess a unique osmoregulatory system of branched protonepheridial tube that end in flame cells  Triploblastic acoelomate Bilaterially symmetrical Dorsoventrally flattened Complex, though incomplete gut  Oral sucker Ventral sucker/ acetabulum Protonephridial tube terminating in flame cell Longitudinal excretory canal Excretory pore Fasciola Excretory system  They are monoecious The gut when present has only one opening. There is no anus  ADVANCEMENTS Triploblastic organization Bilateral symmetry Cephalization Trend toward centralization of the nervous system Well-developed organ-systems  PLATYHELMINTHES CESTODA MONOGENEA TREMATODA TURBELLARIA  Turbellaria The class have the non-parasitic free-living flatworm with leaf-like body Epidermal layer of multiciliated cells covers the body There is no true sucker Presence of subepidermal rhabdites from which mucus trail is derived DIGESTIVE SYSTEM OF PLANARIA  Monogenea Monogenea are parasitic flatworms with single host Body covered by tegument Oral sucker reduced or absent Acetabulum absent  They have anterior prohaptor and large posterior opisthaptor which bears suckers and hooks used as attachment organs They are mostly ectoparasites of aquatic vertebrate especially fishes and amphibians where they feed on the epithelial cells and blood.  The life cycle is different from that of the Trematoda. There is no intermediate host and one egg gives rise to only one adult worm They are monoecious and usually undergo reciprocal insemination The zygote develop into ciliated oncomiracidium larva  Trematoda Flukes are endoparasites of great economics and medical importance eg Fasciola and Schistosoma Body covered by tegument. The cuticle of glycoprotein protect the parasite from their host digestive enzymes They usually possess one or two adhesive suckers for attachment to their host Usually require more than one host to complete their life cycle  Oral sucker Ventral sucker or Acetabulum Male gynaecophoric canal Life cycle of Schistosoma Life cycle if Fasciola  Cestoda Cestodes are very specialized endoparasitic flatworms that entirely lack digestive system The body is covered by nonciliated intergument made of thick cuticle that protect the from the host’s digestive enzymes. The worm is composed of scolex and chains of proglottids.  The knob-like scolex contain suckers and in some forms hooks that anchors the parasite on the host. A narrow neck region connects the scolex the chains of proglottids (stobila) which form greater part of the worm New proglottids are continually being formed at the neck region while old ones detach at the end of the strobila  Tapeworm are monoecious and copulation between proglottids of two different worms often occur or copulation between proglottids on the same strobila are more usual Eggs containing the embryo are protected by shell. The eggs may be shed continually through the gonopore or the terminal gravid proglottis packed with eggs break away from the strobila and rupture within host intestine or rupture outside as it leave with feces.  bladder proscolex Inverted sucker young adult Egg containing hexecanth Cysticercus or Bladderworm embryo Life stages of Taenia solium                    ZOO 116: INTRODUCTORY INVERTEBRATE ZOOLOGY PHYLUM ECHINODERMATA INTRODUCTION The name Echinodermata is derived from their external spines or protuberances Greek words:  “Echinos” = spiny  “derma” = skin  “ata” = to bear Echinoderms are part of the deuterostome evolutionary lineage, sharing deuterostome characteristics with hemichordates and chordates  These are members of the animal kingdom having anus developing from or near blastopore and the mouth developing elsewhere Other features of the deuterostomia branch include:  Coelom budded off from the archenteron  Radial and regulative cleavage development These are some major embryological population Echinoderms are a declining population, 12 known classes have become extinct There are approximately 7000 species living echinoderms  Classification (Common names) Subphylum General description Class Examples 1. Crinozoa Includes the sessile a. Crinoidea (Feather stars and sea echinoderms usually with lilies) stalk, and an anus opening Antedon neocrinus close to the mouth 2. Asterozoa Star shaped, free living a. Asteroidea (Star fishes or sea stars) echinoderms without a Asterias Astropecten stalk b. Ophiuroidea (Bristle stars and basket stars) Ophiothrix, Ophiura, Amphiura 3. Echinoidea Free living, spherical or a. Echinoidea (Sea urchins, sand sausage shaped dollars, heart urchins) echinoderms without a Echinus, Echinocardium, stalk Echinometra viridis b. Holothuroidea (Sea cucumber) Holothuria cucumaria  General characteristics They are exclusively marine and free-living found at all depths in the oceans Adults have a form of radial symmetry referred to as penta-radial symmetry (pentamerous) In the larvae which undergo complex metamorphosis, symmetry is basically bilateral Radial symmetry is an adaptive feature for the sedentary or slow moving animals. In the radial body form, there is uniform distribution of sensory, feeding and other structure around the animal Fig. 1: Penta-radial symmetry in echinoderms  In penta-radial, body parts are arranged in fives or multiple of five, around an oral-aboral axis (Fig. 1) Among the extant echinoderms, some mobile forms have returned to a basically bilateral form Echinoderms exhibit a variety of skeletal structures Generally, calcareous spiny endoskeleton is present in all members This consists of tiny ossicles which are scattered or in the form of plates of calcium carbonate located on dermis and held in place by connective tissues and covered by an epidermal layer  The skeleton is usually modified into fixed or articulated spines that project from the body surface This is the fairly rigid dermal skeleton from Pedicellariae, which are found around the bases of spines, are minute and pincer-like bearing tiny jaws controlled by muscle Pedicellariae serves 3 major purposes: 1. Cleaning the body surface of debris collection 2. Defense 3. Aiding in food captured occasionally Circulation and Coelom Echinoderms possess a unique organ system called Water-Vascular System (W-VS) The system incorporates some flexibility and acts as a hydrostatic skeleton The W-VS is a series of water filled canals, extending from the body surface and superficial extensions that form the podia or tube feet (tentacle-like projections) During embryogenic development, the WVS originates as a modification of the coelom and is ciliated internally The W-VS is laid out in pentameric array, with an oral ring and five radial canals bearing the tube feet  Functioning of W-VS The echinoderm W-VS provides the water pressure that operates the animal’s tube feet Water moves from the madreporite into the ring canal, then into the rays via radial canals, and finally to the tube feet The canals are like a network of water pipes attached to the tube feet Water also leaves the body via the madreporite Fig. 2: Asteroid W-VS  Body is unsegemented (not metameric), may be round, cylindrical or star-shaped with five or more radiating areas (ambulacra) The ring canal usually opens to the outside or to the body cavity through a stone canal and an opening called the madreporite The madreporite may be a sieve-like plate located on the aboral side, as in the sea stars, or a simple opening as in the other members The madreporite may serve as an inlet to replace water lost from the WVS and may help balance pressure difference between the WVS and the outside  Tiedemann bodies are swellings associated with the ring canal. These bodies may be sites for the production of phagocytic cells called coelomocytes, which may be involved in defense mechanisms against diseases Polian vesciles are also associated with the ring canal and function in fluid storage for the WVS Three systems are involved in circulation, namely; 1. W-VS 2. General body cavity 3. Haemal system The body cavity and haemal system The coelom is extensive, forming the perivisceral cavity and the cavity of the WVS All the internal organs of the body are located in this fluid- filled space Cilia lining the cavity maintain circulation of fluid continuously The haemal system is around the ring canal of the W-VS and ran into each arm near the radial canals The haemal system (blood vascular system which is reduced is surrounded by extension of coelom and circulates fluid using cilia that line its channels)  The haemal system is composed of spongy tissue strands and may be involved in transfer of nutritive materials during vitellogenesis (reproduction) Digestive system/feeding Digestive system is usually complete, it may be axial or coiled Anus is present but absent in ophiuroids Echinoderms may be carnivores, grazers, suspension or filter feeders and scavenging detrital feeders Mechanisms are much varied among echinoderms; some attach, lie with the arms forming a bowl with the mouth at the centre  Podia all become active in catching small drifting particles that get trapped on ciliary strings that are retracted into a food groove and passed along to the mouth by joint actions of podia Some are predators on bivalves, fishes, crustaceans, polychaetes and corals Others graze off algae and other organic materials on rock surfaces Some have the capacity to absorb dissolved organic substances directly from sea water Sensory organs There is no head or brain There are a few specialized sensory system of tactile and chemo receptors, podia, terminal tentacles, photoreceptors and statocyst Nervous system Nervous system consists of circum oral rings and radial nerves Osmoregulation and Excretion There are no excretory organs Coelomocytes are present to take up foreign materials introduced into the coelom These migrate through the body wall to the exterior or are released through the papulae (thin walled respiratory projections found over the body surface Digestive wastes are removed via the anus or mouth There is limited ionic regulation Internal osmotic pressure matches that of the sea water, so they are osmotic conformers Respiration A variety of structures are involved in respiratory exchange, namely; Papulae Gills Tube feet Respiratory tree These are essential similar structures in different species across which gaseous exchange can occur They form a link between internal and external environment with the narrowest gap or thinnest of cellular layer Reproduction, regeneration and development Sexes are separate except in a few unusual cases Gonads are large, single in holothuroids but multiple in most others Gonads open externally by gonopore(s) There may be sexual reproduction Fertilization is external Gametes are released to the outside via pores in most echinoderms or by rupture of the pinnule wall  In some, few members of different classes brood the embryo in the genital bursae (ophiuroids), stomach (star fishes) or skin pouches (holothuroids) Some have sexual reproduction by fission under normal conditions Echinoderms can regenerate lost parts. Regeneration is a form of asexual reproduction Central disc is cleaved and each regenerate the disc and missing arms (asteroids, ophiuroids and holothuroids) “Autotomy” is known in some asteroids that discards injured arms  Development is direct in some but the majority have planktonic larval stages The various larval stages are free-swimming and bilateral Different classes of Echinoderms possess different larval stages (Table 1), which show different morphology They undergo complex metamorphosis to radial adult or subadult form with pentameric characters. A form of organization in which body is arranged symmetrically in 5 equal parts around a central core It is actually less distinct in some members but prominent in Ophiuroidea Table 1: Larval forms of different echinoderm classes Class Larval form 1. Asteroidea Bipinnaria Branchiolaria 2. Ophiuroidea Ophiopluteus 3. Echinoidea Echinopluteus 4. Holothuroidea Auricularia Doliolaria 5. Crinoidea Doliolaria Class specific characteristics of Echinoderms Members are all bizarre creatures with sharply distinct characteristics that are just unique to the groups Class Crinoidea These are primitive and possess a stalk used for attachment to the substratum. As a result, the oral surface faces upwards They possess branched arms Tube feet lack suckers Spines, madreporite and pedicellaria are also lacking Some members are free living Class Asteroidea Star-shaped Arms are not sharply delineated from the central disc and contains extensions of the caeca/alimentary canal Also, arms usually bear numerous tube-feet that have suckers Madreporite and anus are aboral in position Ambulacral grooves open and pedicellariae may be present Class Ophiuroidea Star shaped with well defined arms sharply distinct from the central disc There is no anus Madreporite lies on the oral surface Pedicellaria is lacking and tube feet bear no suckers Class Echinoidea Globular, oval or disc-shaped without arms Ambulacral grooves covered for protection Tube feet are suckered Aboral madreporite and anus present Entire body surface is covered with numerous spines, knobs and pedicellaria They possess a chewing apparatus (mouth part) known as Aristotle lantern Class Holothuroidea Body is elongated in the oral-aboral axis forming a cylinder with no skeletal support Muscular body wall is reinforced with small ossicles No spines or pedicellaria Mouth and anus are terminal at opposite ends of the body  ZOO 116: INTRODUCTORY INVERTEBRATE ZOOLOGY PHYLUM HEMICHORDATA  Introduction Phylum Hemichordata is a transition between invertebrates and the chordates Hemichordate is derived from 2 Greek words;  Hemi – Half  Chordae – String  Classification, description and common examples of Hemichordates (Hyman, 1959) Class General description Examples 1. Class Shallow water inhabitants, Acorn worms Enteropneusta wormlike animals that inhabit (Balanoglossus, burrows on sandy shore-lines. Body Saccoglossus) is divided into 3 regions; proboscis, colar and trunk 2. Class With or without pharyngeal slits; Rhabdopleura Pterobranchia two or more arms; often colonial, living in an externally secreted encasement 3. Class Spherical body with ciliary bands Planctosphaera Planctosphaeroidea covering the surface; U-shaped palegica digestive tract; coelom poorly developed; planktonic. Only one species is known to exist  Generalised morphological features of Hemichordates Characteristically, hemichordates lack a notochord but possess a stomochord i.e. mouth-cord which is neither analogous nor homologous to the chordate notochord They are recognized as a likely sister group of echinoderm and chordate because they share certain features in common with them They are deuterostome (along with Echinodermata and Chordata), they are coelomates with radial cleavage. Coelom is divided into 3 portions; protocoel, mesocoel and metacoel  They are all marine, benthic and free-living, solitary or colonial. Some colonial species live in secreted tubes They are vermiform (worm-like), elongate, bilaterally symmetrical animals Their soft body is divided into 3 regions: proboscis lobe, collar, and trunk. The division of the coelom into 3 cavities corresponds to 3 externally visible portions of the body There is no post-anal tail  The blood system has 2 main longitudinal vessels, dorsal, and ventral and a central sinus (dorsal heart vesicle) on the buccal diverticulum. Respiratory system of gill slits connect the pharynx with the exterior. Water enters the mouth as part of the feeding activity and leaves via the dorso-lateral gill slits and pores. Gaseous exchange is thought to occur across the gill bars into the blood vessels within them Excretion- no nephridia. The glomerulus which is connected to blood vessels is suspected to have excretory functions The nervous system is a nerve plexus and covers the body as an epidermal structure. It is thickened in places to form a CNS Reproduction Hemichordates reproduce sexually. However, asexual budding is common in pterobranchs and is responsible for colony formation Most species of Pterobranchia are dioecious while all Enteropneusts are dioecious Fertilization is external and results in the development of a ciliated larvae called tornaria (Enteropneusts) or planula-like larva (Pterobranchia) which swim in the plankton for several days to a few weeks before transforming into adult Larvae of Pterobranchs lives for a time in the tube feet of the female before leaving and settling to the substrate, where it form a cocoon and subsequently metamorphose into an adult Feeding Hemichordates are detritus or filter feeders or ciliary mucus feeders Digestive tract is a simple tube Mouth is located ventrally In acorn worms, detritus and other particles adhere to the mucus-covered proboscis. Tracts of cilia transport food and mucus posteriorly and ventrally  Ciliary tract converge near the mouth and form a mucoid string that enters the mouth Ciliary tract of the collar and trunk transport rejected material and discard it posteriorly Pterobranchs use water current generated by the cilia on their arms and tentacles to filter feed Cilia trap and transport food particles towards the mouth  Phylum : Molusca Dr K. O. K. Popoola  Introduction The name ”Mollusc” if from Latin word meaning soft body They are the largest phylum with 80,000 sps living and 15 fossil sps Highly diverse with wide varieties like ; snails, calms. Squids and octopus Biologically successful; found in fresh water, sea and land They of high economic values; food, defoliators vectors, jewellery and currency  Characteristics features of Mollusca Triploblastic, bilaterally symetrical,. non-metamerically symetrical coelomates  Characteristics features cntd’ Body consist of Head, foot, visceral mass and shell  Characteristics features cntd’ The mantle cavity consists of two gills or ctenidia, the hypobranchial gland, the anus, the kidney opening and oesphradium (is an olfactory organ in certain molluscs) Buccal cavity with unique Radula, a toothed belt used for feeding Coelom reduced to cavity of gonad, kidney and perivisceral Perivisceral is heamoceolic  Biology of Mollusca Circulatory system: Made up of heart and blood vessels with 2 auricles and 1 ventricles Excretory system: molluscs have slightly-more- evolved excretory structures called nephridia. They are tubular or branched structures in contact with the internal body. Nervous system: Circum-pharyngeal ring Buccal ganglia Cerebral Pleural Pedal Parietal Visceral  Biology of Mollusca contd’ Lococmotion; it is highly diverse nad it is by; Gliding, jumping using foot muscles wave contraction Gliding Jumping Swimming in Sea angel Swimming in cephalopod through jet proportions Use of lateral fins by cuttlefish  Reproduction : They undergo sexual reproduction (simple or complex) - Fertilized egg gave Trochophore larva and developed to give veliger - The two larvae forms are typical of Mollusca Apical tuft (cilia Prototroch (cilia) Mouth Metatroch (cilia) Mesoderm Anus Veliger larva Trochophore larva  Feeding: Use radula to scrape rocks at sea to collect microscopic algae and diatoms Scrapped particles are molded together using mucus and send to stomach In stomach partial digestion occurs, which is extracellular Intracellular digestion occurs in digestive diverticular tubules (DDT) Radula in Snail  Clasification The phylum Mollusca consists of 6 classes: (i) Class Aplacophora (“bearing no plates”) worm-like (ii) Class Monoplacophora (“bearing one plate”) primarily, benthic marine habitats. (iii) Class Polyplacophora (“bearing many plates”) are commonly known as “chitons” (iv) Class Bivalvia is a class of marine and freshwater (v) Class Gastropoda (“stomach foot”) E,g snails, slugs, nudibranchi and pteropod (vi) Class Cephalopoda (“head foot” animals) E.g octopus, squids, cuttlefish, and nautilus.  Economic Importance of Mollusca As food to both man and animals For pearls and native currencies Index of aquatic pollution Toxic and can cause food poisoning Sting is fatal and some are venomous Thank you Zoo 116: Introductory Invertebrate Zoology Phylum : Arthropod By K. O. K. Popoola (PhD) Arthropod Introduction to the Phylum Arthropoda - Arthropoda; Latin word meaning – “Arthro” = joints “Poda” = appendages - Largest in numbers among the animal kingdom about 80% of all animals are arthropods estimated to be over 30 million arthropods far more than all other metazoan species combined in virtually every conceivable environment: marine, terrestrial, freshwater, and aerial habitats. Subphylum of Arthropoda Subphylum: Trilobita (extinct) Subphylum: Chelicerata Subphylum: Crustacea Subphylum: Uniramia (insects) ARTHROPODA CLASSIFICATION; COMMON NAMES AND EXAMPLES Phylum Arthropoda Pentatomida Mandibulata Trilobitomorpha Onychophora e.g. Chelicerata Tardigrada Subphylum e.g. Trilobite sp Peripatus sp Myriapoda Insecta Class Crustacean Arachinda Merostomata e.g Limulus sp e.g. Ciripedia e.g. Thysanuran Acarina e.g. Lepas sP Symphylan e.g. Bookworm Rhipicephalus sp (mice Malacostraca & ticks) Protura eg. Crabs Pauropoda Diphura Aranea e.g. Agiop Copepod e.g. Collembola sp (Spider) Order Cyclops sp Chilopoda Isoptera Branchopoda fairy (Centipedes) Pseudoscorpion ships(Daphnia) Hymenoptera e.g. Bee & was Diplopoda Branchiura fish phalarigida (Millipedes) Orthoptera e.g. louse (Argulus sp) Cockroach Diptera e.g. fly Ostracoda e.g. Cypris sp Coleopta e.g. beetle Odonata e.g. Dragon fly ,Damsel fly General characteristics features metamerism (segmented body) jointed appendages bilateral symmetry secreted exoskeleton ecdysis (molting) open circulatory system ventral nerve cord and brain, compound eye Exoskeleton Heamocoelic coelom  Trilobitomorph e.g Trilobite sp EXTINCT GROUP THREE BODY DIVISION INTO LOBES HEAD AND TRUNK SEGMENTATIONS PRESENT OF NUMEROUS JOINTED APPENDAGES FOSSIL RECORD AVAILABLE  Onychophora e.g Peripatus sp Describe as missing link between annelids and the arthropods Greenish- black caterpillar-like Made up of head and trunk; with 2 annulated antennal bearing simple eye at the base Ventrally situated mouth present 14- 42 unjointed appendages at the trunk – conical Parapodia- like legs Body with many tubercles forming bands Feeds on snail, insects, worms etc. which are searched for at night  Chelicerata Introduction mostly terrestrial , with some been marine have two body segments; head and abdomen or (prosoma and opisthosoma) 6 pairs of cephalothoracic appendages presence - chelicerae, pedipalps and 4 pairs legs 77,000 species of chelicerates are alive today. chelicerates have no mandibles and no antennae.  Subphylum Chelicerata a. Xiphosura (horseshoe crab, Limulus polyphemus) b. Arachnida most chelicerates are arachnids several taxa (orders), many are common and familiar SCORPIONES (scorpions ) ARANAE (spiders ) OPILIONES (harvestmen, daddy longlegs ) PSEUDOSCORPIONES (pseudoscorpions) ACARINI (mites and ticks ) c. Pycnogonida (the giant sea spider, Colossendeis australis)  Class: Arachnida ARACHNIDS ARE A CLASS OF JOINTED INVERTEBRATES (ARTHROPODS). ALL ARACHNIDS HAVE EIGHT LEGS, ALTHOUGH THE FRONT PAIR OF LEGS IN SOME SPECIES HAS CONVERTED TO A SENSORY FUNCTION WHILE IN OTHER SPECIES, DIFFERENT APPENDAGES CAN GROW LARGE ENOUGH TO TAKE ON THE APPEARANCE OF EXTRA PAIRS OF LEGS. THE TERM IS DERIVED FROM THE GREEK WORD ( ARÁCHNĒ), MEANING "SPIDER". SPIDERS ARE THE LARGEST ORDER IN THE CLASS. Legs Pro Opis Trombidium holosericeum (a mite) Spider characteristics Giant spider; Amblypygid Pseudoscorpion Galeodes sp  Arachnida condt. Almost all extant arachnids are terrestrial, living mainly on land. However, some inhabit freshwater environments and marine environments. They comprise over 100,000 named species. Feeds on insects- they are predacious, it captures and poison its prey External digestion occurs, by sucking in food into suctorial stomach Excretion is via malpighian tubules and two coxal glands in the prosoma They excretes GUANINE Reproduction is sexual- courtship and mating occurs  Subphylum Crustacea About 26,000 plus known species Two or three body segments With a of pairs antennae Marine, freshwater, and terrestrial Primarily aquatic Free-floating larval stage, nauplius 5 pairs of legs in decapods ANOSTRACA : fairy shrimp and brine shrimp PHYLLOPODA: water fleas MALACOSTRACA: shrimps, crabs, lobsters crayfishes Nauplius COPEPODA: planktonic herbivores, Daphnia CIRRIPEDIA: Lepas and barnacles  Myriapoda SELECT THIS PARAGRAPH TO EDIT Subphylum Myriapoda : This consist of omillipedes, ocentipedes, opauropod and o symphla. The group contains over 13,000 species, most of which are terrestrial Myriapods ranges from having over 750 to 10 legs (Many pairs of legs) They are most abundant in moist forests, few live in grasslands, semi-arid habitats or even deserts  Class Insecta Insects (from Latin insectum, "cut into sections") --- - Chitinous exoskeleton, - Three-part body (head, thorax and abdomen), - Jointed pair of legs (3 pairs of legs) - Compound eyes and - A pair of antennae. Highly diverse group of animals on the planet - Including more than a million described pterygotes and apterygotes subclasses. - Ubiquitous, few are oceans dweller Type of life cycles: Complete and incomplete THANK YOU FOR YOUR ATTENTION Phylum Annelida INTRODUCTION Common name, Segmented and ring worms The name originated from ANNELUS meaning, little ring E.g, ring worm, rag worm, lug worm and leeches Annelida classification Class Polychaeta (many bristles) – most numerous species – Marine species – eg. Neries sp Annelida classification cont’d Class Oligochaeta (few bristles) – Freshwater, marine & terrestrial species Lumbricus terrestris Annelida classification cont’d Class Hirudinea – Fixed numbers of segments (34) – Setae absent – Fresh water specie and ectoprasite Hirudo medicinalis Hirudo medicinalis Annelid Body Plan Setae Class Polychaeta Highly specialized head regions – Antennae – Sensory palps – Feeding appendages Paired extensions of body (parapodia) Nereis sp Often tube-dwelling – Burrow into substrate and secrete mucus/CO3 materials Polychaete Anatomy Polychaete Anatomy (cross section) Polychaeta Lugworm (Arenicola sp) Polychaete Reproduction Dioecious Trochophore larvae Some species develop specialized segments containing gametes – Epitokes – Segments are released and gametes burst out Polychaete Asexual Reproduction Epitokes are essentially buds Clues to ancestral origin of segmentation – Segmentation may have been derived from incomplete budding processes Class Oligochaeta Oligochaete Anatomy Oligochaete Anatomy Transvers section through the gut of an Annelida Seta: a.k.a. Bristles Oligochaete Excretory System Oligochaete Nervous System Oligochaete Reproduction Oligochaete Development For terrestrial oligochaetes, development is direct without any larval forms Some aquatic oligochaetes retain a trochophore-like larval stage Quick and Easy Earthworm Morphology Guide Morphology Number & location of GTs and TPs, location & shape of clitellum Ecology Location of burrows Aporrectodea turgida Lumbricus rubellus Class Hirudinea  SUKER IN LEECHES  Thank you for your attention