Porifera and Cnidarians

Key Questions Describe the distinguishing characteristics of sponges and cnidarians. 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 B. Sexual through spawning: sperm and egg are release. Form a free swimming zygote http://www.youtube.com/watch?v=D9TaVeHCYnk

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 poison-filled, 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=5gXu-4ABXNA

Sexual through spawning http://www.youtube.com/watch?v=oHiVA9J_YIM