Phylum Cnidaria Jellyfish, hydra, sea anemones, & coral.
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Transcript of Phylum Cnidaria Jellyfish, hydra, sea anemones, & coral.
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
Appearance (cont.)
Appearance of a jellyfish
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:
Cnidocyte (stinging cell)
Nematocyst (harpoon)
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) then food is passed to food vacuoles of gastrodermis
• 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 gastrodermal 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; usually have separate sexes (male & female species) but some hermaphrodites do exist
• *MOST ALTERNATE B/W POLYP & MEDUSA LIFE FORM
Reproduction (cont.)
Reproduction (cont.)
Excretion
• mouth/anus- release waste