PORIFERAPorifera- First animal on earth- Symmetry: asymmetrical- Organization: simplest with only cellular levelo No true tissueo No embryonic germ layerso 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- Feeding: suspension/ filter feeders with intracellular digestion- Reproduction:o Mostly monoecious (male and female capabilities) (sequential hermaphrodites- spend some time producing eggs and sometime producing speerm)o Sexual and asexual modes- Architectureo Choanocytes: (collar cells) flagellated cells that produce currents to bring water and food through incurrent pores into either canals or thecentral 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: - Have flagellum that beat and pump water through sponge- have a collar of microvilli- Microvilli trap the food particles from flowing water- Food is phagocytized (engulfed) by the cell- 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 spongocoelo 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 morphologyo 3 classes: Hexactinellida- silicious spicules Demospongiae- silicious spicules Calcarea- calcium carbonate spiculeso Hexactinellida “glass sponges” 6-sided silicious spicules; hexagons join to form complex cages don’t have distinct cells, rather cell membranes are fused; massof protoplasm with many nuclei (syncytial) layers with outer pinacoderm and inner choanosyncytium of fused cell bodies syconoid or leuconoid in form all marineo Calcarea 3 and 4 rayed calcium carbonate spicules (makes them hard) all three architecture forms all marineo 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- Sponge Reproductiono Asexual External budding- buds may or may not detach Fragmentation- Excellent power of regeneration due to totipotency of cells and cellular organization Gemmules- Freshwater demosponges- A dense hard ball of archaeocytes within mesohyl, protected by spicules and collagen- Dormant, an adaption to overwintering harsh conditions- Parent sponge disintegrates and gemmules resume growth in springo -> basically ball of archaeocytes protected by surrounding layer of spiculeso top is micropyle opening where cells exit when favorable conditions resume, the archaeocytes escape through here and develop into new spongeso 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 spongeRADIATARadiata (includes phyla Cnidaria and Ctenophora)- only 2 with radial symmetryCnidaria:- hydroids, jellyfish, sea anemones, corals- either solitary or form colonies- tissue level of organization- gastrulation: ends with 2 germ layers, diploblastic. 2-way/ blind/ incompletegut (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) Inner gastrodermis (from endoderm) Acellular layer of mesoglea “jelly” separates the 2 layers *no mesodermo 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 glideo Mouth faces upward (away from substrate), surrounded by tentacleso Base called pedal disc- Medusa: umbrella shaped bell; floats/swims by contractiono
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