Animal Diversity PDF

Animal Diversity (Morris et al., Ch. 34) Provide some answer to What is an animal? Describe major characters of the animal phyla: Porifera & Cnidaria Annelida & Mollusca Nematoda & Arthropoda Echinodermata & Chordata Describe why I grouped the above phyla together that way ;)...

Animal Diversity (Morris et al., Ch. 34) Provide some answer to What is an animal? Describe major characters of the animal phyla: Porifera & Cnidaria Annelida & Mollusca Nematoda & Arthropoda Echinodermata & Chordata Describe why I grouped the above phyla together that way ;) Remember: Three Domains of Life Life on Earth falls into three main groups or domains Bacteria and Archaea or prokaryotes The third domain includes cells with nuclei, Eukaryota Super Group Phylogeny of Eukaryotes Supergroup Opisthokonta includes all multicellular animals, Fungi and a number of phyla of what were once considered protozoa The animals have been treated historically as a Kingdom Animals are often described by their symmetry Body Symmetry is size and shape of body/parts along an axis or plane Extracellular matrix of animals are extremely important They often form a scaffolding that becomes mineralized and forms bones, shells, or spicules of various animals The extracellular matrix also plays a key role in the development of animals, from sponges to humans Allows for complex multicellularity! Four kinds of molecules that form the extracellular matrix (ECM) collagen - usually long proteins that form a triple helix to form fibres with high tensile strength - primary protein in connective tissues proteoglycans - form the highly viscous fluid of mucus and the extracellular matrix; mucopolysaccharides glycoproteins - large branched molecules that resist compression; return to original shape after being squished integrin - the molecule that connects the extra- cellular matrix to the outside of the cells Development beginning shortly after the zygote is distinct in animals The development of the gastrula from the hollow ball of cells Germ tissue develops during this time -- will differentiate to major tissue types of the body Body Cavity (often, the Coelom) Internal spaces, tissue layers and embryonic development is important for organizing 'higher' animals Bilateria all have a body cavity of some kind This can act as a hydrostatic skeleton or allow internal organs to exist free from the body wall All are multicellular and produce collagen Lots of diversity in symmetry, gastrulation, presence of a coelom\... Some of these morphological characters have been used to organize the animals Porifera - Sponges 5,000 species Primarily marine Sponges are widespread in oceans, have a simple anatomical organization -- no tissues Choanocyte is a specialized cell They feed by drawing water containing food particles and dissolved organic molecules into their interiors Cnidaria -- Jellyfish, Anemone, Corals \>9,000 species In marine and freshwater All cnidarians have: radial symmetry a mouth surrounded by tentacles, with stinging cnidocytes incomplete gut two tissue layers (endodermis and epidermis) cell-free mesoglea, surrounded by epidermis on the outside and Endodermis on the inside Cnidarians Versus Sponges Unlike sponges, cnidarians: have epithelial-lined gut have tissues and organs have a wider array of cell types, including specialized stinging cells are generally predators Bilateria -- Getting "a head" with Cephalization A distinct head and tail Clustering of sense organs on the forward-facing / anterior end Often an anus at the posterior Often, a mouth at the anterior In protostomes, the invagination of the blastula to form the gastrula creates the mouth first; the anus forms later In deuterostomes, the mouth is second Protostomes Lophotrochozoa Ecdysozoa Lophotrochozoa Lophotrochozoans make up almost half of all animal phyla. Annelid worms and mollusks are included in this group. 'lophophre' -- tentacle lined organ for filter feeding 'Trochophore' - a type of larva 'zoan' -- indicates these are animals Annelid Worms Coelom important for hydrostatic skeleton Septa separates body segments Longitudinal & Circular muscles surrounding body Complete gut Well differentiated head and often with appendages for movement (parapodia) or bristles (setae) Phylum Annelida segmented round worms \>22,000 species common in all habitats Metamerism (repeating segmented body) allowed greater complexity \- independent movement of each segment \- requires complex nervous system \- if one segment is injured, the animal can still function Phylum Mollusca \~100,000 species Include snails, slugs, clams, mussels, oysters, squids, octopuses, and nautiluses Molluscs are distinguished by their mantle Molluscs develop from a distinctive larva called a trochophore that has a tuft of cilia at its top and additional cilia bands around its middle. Molluscs: Gastropods There are three main classes (other minor ones too) Gastropoda -- asymmetrical bodies with a well developed head; often with a single shell Molluscs: Cephalopods Cephalopoda -- well-developed head with rings of arms/tentacles; muscular siphon Molluscs Bivalves Bivalvia -- shell with 2 valves; reduced head Lophotrochozoa Lophotrochozoans make up almost half of all animal phyla. Annelid worms and mollusks are included in this group. 'lophophre' -- tentacle lined organ for filter feeding 'Trochophore' - a type of larva 'zoan' -- indicates these are animals Ecdysozoa Ecdysis = molting an outer covering; many will undergo metamorphosis Phylum Nematoda -- unsegmented round worms 25,000 species described Most numerous of all animals? Found in all habitats Important part of soil communities and reach \~2000 individuals per 100g of dry soil C. elegans\...one of the best studied! Phylum Nematoda -- unsegmented round worms Many are important parasites Most humans on Earth live in areas with persistent nematode parasites Phylum Tardigrada \~1,300 species described Found in soils, sediments, leaf litter, mosses & lichens -- basically everywhere that gets wet! Very small, less than 1 mm long Most of the 300--400 known species known live in a water film around mosses and lichens Loved by internet users everywhere Elongated, cylindrical or oval body is unsegmented Four pairs of short, stubby, unjointed legs, each with four to eight claws Body covered by non-chitinous cuticle that is molted four or more times during lifetime Defining characteristic is mouth with stylet Mouth leads to a muscular pharynx adapted for sucking Two stylets protrude to pierce prey (smaller animals) or walls of plant cells and allow them to suck juices Arthropods: Jointed Leg Diversity Modifications and evolution of appendages on the anterior segments of Arthropods produced the major groups we see today. A different type of segmented body \~1.2 million species In all habitats Appendages are jointed Exoskeleton with chitin Metamorphosis A different type of segmented body Modifications and evolution of appendages on the anterior segments of Arthropods produced the major groups we see today. Arthropods: Why so diverse? Arthropods In terms of numbers of species, arthropods are the most successful group of organisms on Earth They occupy an extremely wide range of habitats and some have remarkable tolerance of adverse conditions There are a number of reasons for this success The exoskeleton is highly protective without sacrificing mobility It has several layers It contains chitin, a tough resistant nitrogenous polysaccharide that is insoluble in water, alkalis and weak acids In crustaceans, the outer layer contains calcium salts Because the skeleton can not be enlarged, it must be replaced by a larger one - a process called ecdysis (molting) Arthropods molt 4-7 times before reaching adulthood Molting is hormonally controlled The different stages of development can be very different, thus reducing intraspecific competition Arthropods have a variety of highly developed sense organs The combination of visual, olfactory, tactile, and balance senses make them very alert to their environment The compound eye is sensitive to motion Deuterostome Phylogeny Deuterostomes, the second major group of bilaterians, include humans and other chordates, as well as acorn worms and sea stars. 2 Major phyla Echinodermata Chordata Echinodermata -- a return to radial symmetry \~7,000 species; include urchins, sea stars, sea cucumbers found only in the World's oceans Many are keystone species Echinoderms have pentaradial symmetry and a water vascular system that enables tube feet to facilitate movement Water vascular system Hydraulic system that uses muscular pressure to coelom Ampulla are muscular sacks that hold fluid above the podia contraction forces fluid into the podia and stiffens them for walking Phylum Chordata (and the Vertebrates) \>81,000 living species of chordates Subphylum Vertebrata exclude the protochordates 64,000 living species About half are bony fishes Chordates have the following shared characters: 1.notochord 2.dorsal tubular nerve chord 3.pharyngeal pouches 4.Endostyle or Thyroid gland 5\. postanal tail Notochord is a cartilaginous rod \- Can be found in all embryonic and some adult chordates \- Serves as an endoskeletal structural element (precursor to the vertebral column) \- provides directional signaling to surrounding tissues during development \- has elastic 'spring-like' properties to facilitate movement Three Major Subdivisions: Craniata or Vertebrata Tunicata Cephalochordata Subphylum Vertebrata or Craniata Animals with heads and skulls, vertebrae and spinal cord, and a lot of things that we have in common with fish, frogs, flamingos and zebras Generally known as vertebrates, but craniates is more appropriate since all have a head with a brain, while agnathans (jawless fish) lack vertebrae Notochord, dorsal nerve chord, pharyngeal pouches, and postanal tail - all present in some stage of development Endoskeleton consisting of vertebral column (except agnathans), limb girdles, two pairs of jointed appendages, and a head skeleton (skull) Unique layers of tissue in their skin many modifications of skin characteristic of classes (glands, scales, feathers, claws, horns and hair) Muscular perforated pharynx Many muscles attached to skeleton for movement Ventral heart (2-4 chambers); red blood cells Complete digestive system ventral to spinal column Well developed coelom mostly filled with viscera Excretory system of paired kidneys with ducts to cloaca or anal region Highly differentiated brain Endocrine system of ductless glands scattered through body; hormones released directly into blood or lymph (e.g. hypothalamus, pituitary gland, pineal gland, thyroid gland, adrenal glands, pancreas) Individual producing either sperm or eggs (nearly always); each with paired gonads and ducts leading to cloaca or special anal openings All are multicellular and produce collagen Lots of diversity in symmetry, gastrulation, presence of a coelom\... Some of these morphological characters have been used to organize the animals