Presentation on theme: " Have tentacles with nematocysts near mouth. Nematocysts are stinging cells Cnidaria is Greek for “stinging cell” Examples: jellyfish, sea anemone,"— Presentation transcript:
Have tentacles with nematocysts near mouth. Nematocysts are stinging cells Cnidaria is Greek for “stinging cell” Examples: jellyfish, sea anemone, coral, hydra Most are marine, but some are freshwater. Nematocysts are used in defense and for feeding
Radial Symmetry Central hollow body opening with one body opening. Body is two tissue layers thick Ectoderm- outside layer Endoderm- inside layer No skeleton. Water supports the body. Coral and sea anemone are sessile or stationary; adult jellyfish are moved by current. Some jellyfish can swim.
Two basic shapes Polyp vase-shaped, mouth on top Medusa cup-shaped, mouth on underneath
Nematocysts stun prey Tentacles put prey in mouth. Digestion takes place inside body. Wastes exit through mouth.
Gas Exchange by diffusion Nerve net concentrated near mouth No circulatory system
Asexual Budding Regeneration Sexual External fertilization takes place when eggs and sperm are released into the water.
Provide homes for other organisms Coral grouping together makes coral reefs Jellyfish product poisons that are studied to better understand our own nervous systems.