Invertebrates Asymmetrical no symmetry at all No true

Invertebrates

• Asymmetrical (no symmetry at all) • No true body cavities (coeloms), just cells and tissues surrounding a waterfilled space. • Debate on whether a sponge is multicellular or colonial.

Sponges • http: //www. youtube. com/watch? v=Rm. PTM 965 -1 c (sponges) • http: //www. youtube. com/watch? v=KOFFz XNYJG 0 (sponges) • http: //www. youtube. com/watch? v=Iy. UFG_ F 3090 (choanocytes)

Intracellular digestion • There is no digestion in the spongocoel.

• Amoebocyte: named because they move by pseudopods, - take food from the choanocyte, form the skeletal fibers (spicules) • Spongin: a network of flexible fiber proteins in body wall • Spicules: fibers made from the amoebocyte, they are sharp and made from calcium carbonate or silica. Function: provide structural support as well as defense against predators.

• Choanocyte: flagellated cells, also called collar cells, that line the spongocoel and trap food • Porocytes: donut shaped pores that open and close to control water flow • Ostia: small pores in the walls of sponges, water enters • Osculum: large opening that water flows out of, under certain conditions cells around the osculum contract (open and close) • Spongocoel: the central cavity of a sponge

Cnidaria • • Radial symmetry (infinite lines of symmetry) Two germ layers (TRUE germ layers): Diploblastic No coelom Extracellular digestion in the gastrovascular cavity

Cnidarin: general body plan

Cnidocytes with nematocyst harpoons: namesake of the phylum • Before After Bumps are the cnidocytes

Planula larvae • Ciliated larva stage of jellyfish and corals

Cnidaria: Scyphozoa

• http: //www. youtube. com/watch? v=v 9 j 9 i. O 6 Zy 4 o&feature=Play. List&p=E 9 E 1093124 E 2 F 9 C 9&playnext=1&index=3; jellyfish movement • http: //www. youtube. com/watch? v=M 9 MMp 7 QX 6 e 0&feature=Play. List&p=E 9 E 1093124 E 2 F 9 C 9&playnext=1&index=2 polyp stage • http: //www. youtube. com/watch? v=1 m. Io 7 YB 5 DKY&feature=Play. List&p=E 9 E 1093124 E 2 F 9 C 9&playnext=1&index=1 more polyp

Jellyfish bloom

Cnidaria: hydrozoa • Portuguese Man-of-War are colonies of four kinds of highly modified polyps: feeding polyps, reproductive polyps, etc. . • Hydra catching food: http: //www. youtube. com/watch? v =Kukv 0 At. IVd. U&feature=related • Hydra; http: //www. youtube. com/watch? v =yq. Xka. Zwiu 6 s&feature=related

Anthozoa: flowering cnidarians • Sea anemone • Corals

Reef evolution

Reef types • Fringing reef atoll Barrier reef

Ctenophora: close relatives to cnidarians • Comb jellies: secrete jelly instead of the stinging nematocysts of the cnidarians • Colloblasts are the jelly making cells

Ctenophora: comb jellies

Comb jellies • http: //www. youtube. com/watch? v=G 7 WT 8 1 uk. HZE