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Phylum Porifera (pore bearers) pages 664 to 667 Sponges YouTube - The wonderful world of the sea sponges- The Abyss- BBc Wildlife Sponges Scuba sponge Glass sponge Variety Unidentified sponge Phylum Porifera • • • • • sponges various shapes, colours, sizes at least 10 000 species may live alone or in colonies Have no tissues therefore limited (no muscle, no movement; no nerve tissue, no coordiation) Characteristics of Phylum Porifera 1. Multicellular – Specialized cells in two main layers a. Outer layer: Epidermis (flattened cells) : Protective Layer b. Inner layer : Flagellated cells that set up water currents, drawing H2O which carries its food into the sponge • Between these 2 layers is a jelly-like substance containing: a. spicules: -provide support as they are made of silicon (glass) or calcium carbonate (lime). -provide protection from predators. (Sharp needles in mouth!) b. amoebocytes which: - are not specialized but can carry food particles (diatoms, algae) and water that were digested by the collar cells. - pick up waste and carbon to take back to the collar cells for disposal Sponge eating • http://www.youtube.com/watch?v=RmPTM96 5-1c&feature=related Choanocytes (Collar cells) Characteristics continued 2. Motile when “young”; sessile as adults 3. Body cavity exists as a hollow sac with many pores and one large opening called the osculum (at top). Food is digested in the collar cells. 4. Reproduce asexually and sexually. Asexually by budding (small groups of cells grow from the body wall of the adult and break off to attach somewhere else) and by fragmentation. Budding Sexually: Most are hermaphrodites (organisms that produce both eggs and sperm but not at the same time so they do not fertilize themselves). They need another sponge of the same species. EX. Sperm is released into the water and enters a pore of another sponge. It enters a collar cell where an amoebocyte takes it to an egg. A zygote results. Mitosis (cell division) occurs to develop a flagellated larva. It is motile but will settle on a surface and grow into an adult. • Spawning Sponges - YouTube Questions • Page 667 1, 2, 1. What features do sponges share with other animals? 2. How do sponges use water to carry out essential functions? 4. Why would sponges not be able to live on land? Phylum Cnidaria (Cnidarians) • Jellyfish, sea anemones, hydras, and corals http://www.youtube.com/watch?v=AjMWOeM3uA Phylum Cnidaria • 90 000 species • aquatic, mostly in salt H2O (all except hydra) • very beautiful Characteristics 1 Radially symmetrical (Tentacles arranged around an opening like spokes on a wheel) 2 Have 2 embryonic germ layers: ectoderm (outside) and endoderm (inside). Ectoderm and Endoderm separated by jelly-like material. 3. Exist in one of two basic shapes: - when young: a tube-like, vase-shaped hollow body called a polyp. The upward facing mouth is surrounded by tentacles. Sessile. - when mature: opened umbrella shape or bell-shaped called a medusa. The downward facing mouth is surrounded by tentacles. Motile. (Ex. Jelly fish, Aurelia) 4. Possess nerve tissue but no brain. Respond to stimuli when touched—flatten out and pull in tentacles 6. Carnivorous -Tentacles have specialized cells containing nematocysts (coiled stinging hair-like structures). Each is attached to a fine thread that pulls food into the mouth. 1000s+ in one tentacle. Nematocyts penetrate prey or predator and paralyze them. Nematocysts at work Eating continued - No digestive system. Food enters the mouth with the help of the tentacles. Enzymes are secreted by endoderm cells. - Some endoderm cells use phagocytosis to engulf large particles and digestion then occurs in the endoderm cell itself. Note: There is no need for an organ systems because there are only 2 layers of cells. Water can diffuse in and carbon can diffuse out. 7. Reproduction: - Asexually by budding - Sexually when conditions are harsh. Many are hermaphroditic but some have different sexes. The ectoderm develops the gonads which are organs for sexual production: male-testis female-ovary Sperm swims.