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Sponges

Sponges. Phylum Cnidaria. Jellyfish, Sea Anemones. Basic Info. Soft-bodied animals with stinging tentacles Live as singles, groups, and in connected colonies Many different species (~9000) All species have stinging cells called nematocysts. Habitat. Most species live only in the sea

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Sponges

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  1. Sponges

  2. Phylum Cnidaria Jellyfish, Sea Anemones

  3. Basic Info • Soft-bodied animals with stinging tentacles • Live as singles, groups, and in connected colonies • Many different species (~9000) • All species have stinging cells called nematocysts

  4. Habitat • Most species live only in the sea • Found in all marine environments

  5. Body Structure • All have radial symmetry • Polyp – sessile and flowerlike • Medusa – motile bell-shaped

  6. Gastrovascular Cavity • Three cell layers: Epidermis, mesoglea, gastroderm • Gastroderm layer lines a central cavity called the gastrovascular cavity

  7. Form and Function

  8. Nematocysts – stinging cells located in tentacles • Shoots a poison dart into prey that paralyzes or kills it. • Tentacles – long extensions of the body help push food into the mouth

  9. Body Systems • Digestive: • Gastrovascularcavity – breaks down food into smaller, digestible pieces. • Mouth – entrance for food and exit for wastes • Gvccavity branches in some cnidarians to transport food throughout the body. • Respiratory and Excretory: • Gastrovascular cavity filled with moving water for exchange of materials • Nervous: • Simple nerve net concentrated around the mouth

  10. Organs • Some medusae have simple organs called statocysts and ocelli • Statocysts are used for balance and orientation • Ocelli are “eye-spots” that detect light.

  11. Movement • No muscular system • Epidermal cells can change shape to cause movement • Medusae draw in water and expel it under high pressure to move – (jet propulsion) • http://www.youtube.com/watch?v=8tp_YxqLtYs

  12. Reproduction • Most can reproduce sexually or asexually • Budding is common in polyps • Medusae often release gametes into the water where they can fertilize internally or externally

  13. Class Hydrozoa • Most common is a Hydra • Interesting lifecycle • Mostly polyp form

  14. Class Scyphozoa • Jellyfish • Life cycle similar to hydra • Can be up to 2 metres wide

  15. Class Anthozoa • Anemones and Corals • Polyp throughout life cycle • Some sea anemones have photosynthetic symbionts

  16. Importance • Corals and anemones provide extensive habitats for fish • Medical research due to the toxicity of some of the chemicals they produce

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