Phylum Porifera: Non-Chordates

• Non-chordates can be classified into different phyla

Phylum-Porifera Features

• Primitive multicellular animals exist with a cellular grade of organisation
• Most are free-living and marine, found either solitary or colonial
• Body is asymmetrical, lacking true tissues or organs
• Numerous incurrent pores, ostia, lead into a spongocoel through a canal system
• Spongocoel opens outside through oscula, one or two large excurrent pores
• Choanocytes (collar cells) line canals and the spongocoel
• Sensory and nerve cells missing in sponges
• Diploblastic body wall
• Outer layer, pinacoderm
• Inner layer, choanoderm
• A mesenchyme present between the layers
• Endoskeleton made of calcareous or siliceous spicules or spongin fibers
• Digestion is intracellular and holozoic
• Respiration and excretion occur through simple diffusion
• Reproduction occurs via asexual (external or internal buds) or sexual methods
• Gemmules are masses of archaeocytes
• Choanocytes possess flagellum to maintain water current and ingest food
• Leucosolenia has canal system of asconoid type
• Nutrition is holozoic, digestion is intracellular and food vacoule transfers to amoebocytes
• Ammonia is the chief nitrogenous waste
• Leucosolenia reproduces asexually through external budding, and sexually by syngamy
• No special gonads, so sperms and ova develop from archaeocytes
• Fertilisation is internal, cleavage is equal and holoblastic
• Parenchymula larva swims freely and attaches to substrate

Classes of Phylum-Porifera

• Class Calcarea habitat is exclusively marine
• Class Hexactinellida habitat is exclusively marine
• Spicules made of calcium carbonate in Calcarea
• Spicules made of silica in Hexactinellida
• Class Demospongiae live in marine or freshwater habitats
• Spicules made of spongin fibers, or may be absent in Demospongiae
• Sycon and Leucosolenia are examples of Calcarea
• Euplectella (venus flower basket) and Hyalonema (glassrope sponge) are examples of Hexactinellida
• Spongilla (freshwater sponge) and Cliona (boring sponge) are examples of Demospongiae

Leucosolenia Details

• Body cylindrical and has radial symmetry
• Porocytes are special cells allowing incoming water passage
• Pinacoderm is the outer cell layer made of pinacocytes
• Mesenchyma lies between pinacoderm and inner layers and contains free amoebocytes and skeletal elements
• Archaeocytes are undifferentiated totipotent cells
• Chromocytes possess pigment granules
• Thesocytes contain food granules for reserve
• Myocytes are contractile and spindle-shaped -Trophocytes provide developing cells nutrients
• Gland cells secrete a slimy substance
• Sex cells develop from archaeocytes during times of breeding
• Proterospongia are the link between Protozoa and Porifera

Phylum-Coelenterata Features

• Radially symmetrical
• Diploblastic
• Multicellular animals
• Tissue grade of organisation
• Freshwater or marine habitats
• Solitary or colonial, free-swimming or sedentary
• A mouth at the oral end leads to a gastrovascular cavity or coelenteron
• Tentacles present for locomotion and food capture
• Epidermis contains epitheliomuscular cells for musculature, cnidoblasts, totipotent interstitial cells, nerve cells and sensory cells
• Cnidoblasts, nematocysts or stinging cells, are in the ectoderm of tentacles for offense and defense
• Digestion is both intracellular and extracellular
• Respiration and excretion through simple diffusion
• A network of nerves spreads throughout the body
• Polymorphism, different individual types exist in the colony for different functions, these individuals are called zooids
• Reproduction occurs asexually through external budding or sexually via gamete formation
• Metagenesis is the alternation of polypoid and medusoid phases, prominent in the life cycle of Obelia

Classes of Phylum-Coelenterata

• Class Hydrozoa lives in freshwater or marine habitats
• Class Scyphozoa and Anthozoa both live exclusively in marine habitats
• Hydrozoa have polypoid or medusoid forms
• Scyphozoa are medusoid
• Anthozoa are polypoid
• Hydra, Obelia and Physalia (Portuguese man of war) exemplify Hydrozoa
• Aurelia and Cassoprea (jelly fishes) represent Scyphozoa
• Sea anemone corals
• Fungia
• Gorgonia (seafan) are examples of Anthozoa

Hydra Details

• Trembley discovered it in 1744, Linnaeus named it Hydra in 1758
• It is diploblastic and has radial symmetry
• Separate coelom is absent so it is acoelomate
• Coelenteron or gastrovascular cavity is the primary body cavity
• Nematocysts play important roles in locomotion and food capture
• Carnivorous
• Extracellular digestion primarily, followed by intracellular
• Anus and true nerves are absent
• Reproduces both asexually and sexually
• Has a planula-like stage but no free larval stage; no moulting occurs during development

Phylum-Ctenophora

• Consists exclusively of marine animals to swim via cilia
• Radially symmetrical
• Diploblastic, eg Ctenoplana

Phylum-Platyhelminthes

• Bilaterally symmetrical
• True multicellular organization
• Organ grade organization
• Live free (aquatic or terrestrial) but are mostly parasitic (ecto or endoparasites) with dorsoventrally compressed, leaf-like bodies
• Triploblastic with blind sac body plan
• Absent body cavity
• Mesenchyme fills the space between the body and the alimentary canal
• Incomplete digestive system
• Anus is absent
• Simple diffusion for respiration
• Specialized flame cells or solenocytes carry out excretion

Fasciola hepatica

• Commonly known as liver fluke
• Inhabit the liver and bile ducts of sheep, goat, rabbit, pig, dog and humans
• An endoparasite
• Completes life cycle in two hosts
• Sheep acts as primary vertebrate host, Limnaea tranculata serves as intermediate gastropod snail host
• Head lobe (oral cone) is the broad anterior part that connects oral sucker that surrounds its muscular tip
• Ventral sucker or posterior sucker of acetabulum is at some distance from the oral sucker
• Both oral and ventral suckers have radial muscles
• Alimentary canal is incomplete
• Only one opening for ingestion and egestion
• Blind sac body plan is its alimentary canal
• Gonopore or genital opening is present ventrally in between the oral and ventral suckers
• At breeding season, the Laurer's canal opens temporarily on the dorsal side
• Anaerobic or anoxybiotic because of parasitic mode of life
• Monoecious (hermaphroditic)
• Both male and female genital ducts open into genital atrium

Characteristics of Classes of Platyhelminthes

• Class Turbellaria are free-living in aquatic habitats with present digestive and Planaria (the flatworm) as an example
• Class Trematoda are ecto or endoparasites habitats with present digestive and Fasciola (liver fluke) or Schistosoma (blood fluke), as example
• Class Cestoda are endoparasite habitats with absent digestive and Taenia solium(tapeworm) , as example

Ascaris lumbricoides Detail

• Roundworm
• Common endoparasite
• Occupies the small intestine of children
• Males are smaller
• A curved tail
• Have two pineal setae (copulatory organs), cloaca
• *- Syncytial epidermis
• Body cavity is pseudocoel
• Excretory system consist of one renette cell
• Monogenetic
• Only host required for development
• Rhabditiform larva
• Ascariasis disease

Wuchereria bancrofiti Detail

• Also known as filarial worm
• Causes elephantiasis
• Associated with symptoms like
• Headaches
• Anemia
• Fever
• Tumors
• Swelling in limbs

Phylum: Aschelminthes

• Mostly parasitic, some are free-living
• Cylindrical in shape and bilateral symmetry
• Body wall has a cuticle, epidermis, and musculature
• They have a false body pseudocoelom (not lined by mesodermal epithelium)
• Derived from embryonic blastocoel
• Complete digestive system
• Diffusive respiration
• Longitudinal nerve cords
• Nerve ring present
• Sexual reproduction
• Males usually shorter than females like the ones of:Ascaris (parastic roundworm or facultative aerobic), Rhabditis (free-living), Dracunculus (guinea worm), Enterobius (pinworm), Trichuris (whip worm), Wuchereria (filarial worm), and Loa loa (eye worm).

Classifications of Aschelminthes

• Aphasmidia: Lacks phasmids near body end, amphids of various types and an example is Trichinella (trichina worm)
• Phasmidia: Has phasmids near posterior end of body, preent amphids near anterior end and Ascaris and Wuchereria are examples

Traits: Phylum-Annelida

• Aquatic and terrestrial
• Long and Cylindrical
• Metamerically segmented
• Cuticle, muscles, and epidermis compose the body wall
• Triploblastic condition
• True coelom (body cavity)
• Has alkaline fluid, also known as coelomic fluid which contains corpuscles
• Circular nucleated cells, phagocytic, mucus and chloragogen cells occur
• Closed circulatory system
• Plasma dissolves hemoglobin directly
• Consist of nerve ring, gangila, and double ventral nerve cord

Traits: Phylum-Annelida (cont.)

• Setae and/or parapodia aid locomotion
• Has cutaneous layer
• Chloragogen aid liver-like qualities
• Sexual reproductions
• Nephridia aid excretion
• Free living or marine(freshwater) organisms

Traits: Earthworm

• Setae help in locomotion
• Porphyrin gives a clay-like brown appearance
• Three body sections, numbered parts
• Segmental organization
• Schizocoel coelem that is true
• milky white and alkaline coelomic fluid inside
• Hydraulic skeleton made by fluid in cavity
• Chloragogen cells involved in waste, food and excretion
• Typhlosole in segment(glandular/vascular), increased absorption
• closed circulatory system that carries hemoglobin
• Respire cutaneously, has no special organ
• Nephridia analogous to a vertebrate kidney for excretion
• Spermathecal pores for reproduction that are pairs Clitellum creates cocoons
• direct but unequal cleavage with no clear larval stage (oligochaeta)

Hirudinaria (leeches)

• Freshwater or temporary ectoparasite with annuli
• Sanguivorous( eats blood) and feeds on cattles blood
• blood is stored in a crop containing 10 chamber and an anticoagulant called (hirudin) mixes with the blood
• protandrous but cross-fertilization occurs within a direct developmental process
• cutaneous with ventral pores on sides

Traits: Phylum-Arthropoda

• Over 75 percent fall to animals make up the largest portion of the animal kingdom
• Some are parasitic, terrestrial or aquatic
• Segmented,elongated bodies that contains a head, throax, and abdominal section
• The bodies has a chitinous exoskeleton for support
• Excreted through malpighian tubules or coxal glands
• The circulatory system is open
• The digestive system is complete that allows the digestive system to pass through
• Nervous is made of nerve ring as well that has ventrally arranged.
• Jointed appendages help locomotion and movement
• sexually with indirect or direct development involved
• Apis, arnes, palaemon scolependra and photinus for biolumuniscencent examples

Characteristics of different classes in Phylum-Arthropoda

• Diplopoda: Terrestrial with milipede example, many walking legs, chitinous exoskeleton
• Chilopoda: Terrestrial with centipede example, many chitinous exoskeleton,
• Crustacea: Aquatic with some walking legs through 5 pairs with crab and lobster example
• Archnida: Arachnida with terrestrial with Scorpion, chitinous exoskeleton Three Pairs Insecta : Butterflies, Three Pairs Insects All posses trachea

Explore the features of Phylum Porifera, a group of primitive multicellular animals. Learn about their cellular organization, body structure, and unique characteristics such as choanocytes and spicules. Understand their modes of digestion, respiration, and reproduction.