Porifera and Cnidarians Key Questions 1 Describe the
Porifera and Cnidarians
Key Questions 1. Describe the distinguishing characteristics of sponges and cnidarians. 2. Describe how sponges and cnidarians feed and reproduce.
Phylum: Porifera (Sponges)
Characteristics: • Asymmetrical: no front, back, left or right • No complex organs • Sessile (attached at base)
Feeding: A. Sponges are filter feeders http: //vimeo. com/40240443
B. Choanocytes: Specialized cells that use flagella to move a steady current of water though the cell. C. The movement of water is the mechanism for feeding, respiration, circulation and excretion.
Support System • Mineral spicules
Reproduction A. Asexual through fragmentation: a piece of sponge can regrow into an adult sponge
B. Sexual through spawning: sperm and egg are release. Form a free swimming zygote http: //www. youtube. com/watch? v=D 9 Ta. Ve. HCYnk
Cnidarians (jellyfish, sea anemone, hydra, coral)
Characteristics A. Radial Symmetry B. Incomplete gut (has a mouth but no anus) C. Jelly-like
A. Cnidocytes and Nematocyst 1. Cnidocytes are stinging cells that are located along tentacles 2. Nematocyst is a poisonfilled, stinger structure that contains a tightly coiled dart
B. Circulation, respiration, and excretion: food and waste are transported throughout the body and out of the body wall through the mouth.
III. Support system A. Hydrostatic skeleton: the water pressure gives the jellyfish its shape
B. Polyp: tentacles up
Medusa: Tentacles down
IV. Reproduction Asexual through budding http: //www. youtube. com/watch? v=5 g. Xu-4 ABXNA
Sexual through spawning http: //www. youtube. com/watch? v=o. Hi. VA 9 J_YIM
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