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Phylum Cnidaria. Jellyfish, hydra, sea anemones, & coral. Appearance. Polyp : cylindrical, pine shaped animals that are usually attached to a rock or Ex. Hydras, sea anemones, corals Medusa : bell-shaped body; umbrella
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Phylum Cnidaria Jellyfish, hydra, sea anemones, & coral
Appearance • Polyp: cylindrical, pine shaped animals that are usually attached to a rock or Ex. Hydras, sea anemones, corals • Medusa: bell-shaped body; umbrella Ex. Jellyfish *Have 2 tissue layers: ectoderm & endoderm
Symmetry • Radial symmetry
Skeletal/Muscle System • most have primitive muscle cells; coral have external skeleton of calcium carbonate
Capturing PreyLET’S EAT!!! • cnidarians are carnivores (eat meat) that use tentacles arranged in a ring around their mouth to capture prey • when a “trigger” is stimulated on a stinging cell called the cnidocyte, a harpoon or nematocyst shoots out & injects poison into the prey
Capturing Prey: Cnidocyte and Nematocyst at work: WE DO WORK!!! Nematocyst (harpoon) Cnidocyte (stinging cell)
Digestion • Sac w/ a digestive cavity (gastrovascular cavity) w/ a single opening that acts as a mouth/anus Jellyfish Hydra
Digestion (cont.) • food is pushed into the gastrovascular cavity where digestion begins (extracellular digestion) • undigested remains leave through the mouth/anus
Nervous System • Nerve Net- Cnidarians do not have a brain but they have simple sensory receptors that detect & respond to stimuli
Circulation • NONE!!
Respiration • Diffusion- oxygen from water moves into sponge cells (high to low)
Reproduction • Asexual – budding- formation of outgrowths that pinch off from parent to live independently • Sexual- forms a zygote and free swimming planula that settles on ocean floor • *MOST ALTERNATE B/W POLYP & MEDUSA LIFE FORM
Excretion • mouth/anus- release waste