PORIFERA Porifera First animal on earth Symmetry asymmetrical Organization simplest with only cellular level o No true tissue o No embryonic germ layers o Specialized cell types form parts cells cant live alone Movement sessile No nervous structures Circulation transport diffusion and cell to cell Osmoregulation excretory simple diffusion with water Reproduction Feeding suspension filter feeders with intracellular digestion o Mostly monoecious male and female capabilities sequential hermaphrodites spend some time producing eggs and sometime producing speerm o Sexual and asexual modes Architecture o Choanocytes collar cells flagellated cells that produce currents to bring water and food through incurrent pores into either canals or the central cavity and out the osculum o Incurrent pores pores on sponge wall ostia ostium o Ostium outside surrounding of sponge where the pores are where water comes in through o Osculum opening at top of sponge for outgoing water WATER IN OSTIUM WATER OUT OSCULUM 3 Types of Sponge Architecture o Asconoid simplest basic water in out flow Spongocoel aka atrium cavity inside the sponge lined with beating flagellated choanocytes Choanocytes sponge Have flagellum that beat and pump water through Food is phagocytized engulfed by the cell have a collar of microvilli Microvilli trap the food particles from flowing water passed on to other cells amoebocytes leads to transfer of food particles from cell to cell via amoebocytes can become sperm form layer called choanoderm Pinacocytes outer sponge cells that form the Pinacoderm Thin tightly packed layer Outermost Mesohyl gelatainous matrix beneath outer pinacoderm layer Contains the amoebocytes and skeletal elements Skeletal elements spicules and spongin fibers Porocytes surround canal openings pores contract to regulate water flow Archaeocytes aka amoebocytes totipotent cells ie stem cells can change into any type of sponge cell Move through mesohyl Ingest phagocytosis and digest food transferred from choanocytes Transport nutrients to other cells can become eggs Sclerocytes responsible for secretion of spicules Spongocytes secrete skeletal fibers made of the structural protiens collagen and sponging Surface area and volume limit asconoids to very small size o Syconoid sponges Larger than asconoids Increased surface area for filtering by folding the asconoid surface creating canals o Flagellated choanocytes inside radial canals instead of spongocoel o Leuconoid sponges Further increase in surface area with subdivided flagellated canals flagellated chambers Can be encrusting sponges No longer has a distinct spongocoel atrium multiple oscula exits for filtered water Skeletal Support o 2 components Spicules Structural protein matrix Major protein collagen Distributed in the intercellular mesohyl matrix class Demospongia uses spongin a form of collagen prevents collapse of chambers and canals Classification o Based on spicule morphology o 3 classes Hexactinellida silicious spicules Demospongiae silicious spicules Sponge Reproduction o Asexual Calcarea calcium carbonate spicules o Hexactinellida glass sponges 6 sided silicious spicules hexagons join to form complex cages don t have distinct cells rather cell membranes are fused mass of protoplasm with many nuclei syncytial layers with outer pinacoderm and inner choanosyncytium of fused cell bodies syconoid or leuconoid in form all marine o Calcarea 3 and 4 rayed calcium carbonate spicules makes them hard all three architecture forms all marine o Demospongiae Most species Mostly marine and leuconoid Support from spongin fibers siliceous spicules or CaCO3 or both Spicules don t form the same shapes as in the other 2 classes External budding buds may or may not detach Fragmentation Excellent power of regeneration due to totipotency of cells and cellular organization Gemmules A dense hard ball of archaeocytes within mesohyl Freshwater demosponges protected by spicules and collagen Dormant an adaption to overwintering harsh Parent sponge disintegrates and gemmules resume conditions growth in spring o basically ball of archaeocytes protected by surrounding layer of spicules o top is micropyle opening where cells exit when favorable conditions resume the archaeocytes escape through here and develop into new sponges o Sexual When stimulus is right flagellated choanocytes become sperm and are released into the water broadcast spawning Released sperm enter another sponge and are phagocytized by choanocytes which lose their flagella and collar The choanocytes become amoeboid transfer into carrier cells and deliver the sperm traveling through the mesohyl to fertilize egg cells The egg cells come from archaeocytes Fertilized egg developes into simple parenchymula or amphiblastula larva Balls of cells with flagella on outside Larva exits parent travels for a few hours settles and develops into new sponge RADIATA Radiata includes phyla Cnidaria and Ctenophora only 2 with radial symmetry Cnidaria hydroids jellyfish sea anemones corals either solitary or form colonies tissue level of organization gastrulation ends with 2 germ layers diploblastic 2 way blind incomplete gut only one opening gut is called Gastrovascular Cavity either slow swimming or sessile locomotion sensory nerves nerve net rhopalia statocysts ocelli in scyphozoan medusae circulation transport gastrovascular canals in scyphozoan medusae respiration simple diffusion with environment feeding mostly carnivorous capture prey with tentacles digestion is both extracellular and intracellular reproduction both monoecious and dioecious species sexual and asexual modes Architecture o Body wall of two tissue layers Outer epidermis from ectoderm Acellular layer of mesoglea jelly separates the 2 layers no Inner gastrodermis from endoderm mesoderm o Gastrovascular cavity communicates with the surrounding medium through single opening mouth also acts as anus surrounded by tentacles Polyp cylindrical usually attached to substrate some can glide o Mouth faces upward away from substrate surrounded by tentacles o Base called pedal disc Medusa umbrella shaped bell floats swims by contraction o Mouth faces downward surrounded by tentacles Some cnidarian live in polyp or medusa forms only some alternate Cnidocyte cells o Cnidae organelles with cnidocytes Type of this nematocyst An organelle Most common cnidae Ejects harpoon like barbed and stinging toxic threads Capped by an operculum within the cnidocyte A capsule with coiled
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