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Introduction to Cnidarians

Introduction to Cnidarians. 6th Grade. What is a Cnidarian?. “NYE-DARE-EE-UN” Invertebrates that have stinging cells and take food into a central body cavity. Cnidarians use stinging cells for what TWO purposes? . Defend themselves Capture food .

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Introduction to Cnidarians

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  1. Introduction to Cnidarians 6th Grade

  2. What is a Cnidarian? • “NYE-DARE-EE-UN” • Invertebrates that have stinging cells and take food into a central body cavity

  3. Cnidarians use stinging cells for what TWO purposes? • Defend themselves • Capture food

  4. Cnidarians can have 1 of 2 body plans • polyp: 2) medusa vase-shaped body plan bowl-shaped body plan

  5. BOTH body plans have… • radial symmetry • a central hollow cavity • tentacles that contain stinging cells

  6. Polyp • Vase-shaped body plan • Mouth opens at the top and tentacles spread out from around the mouth • Most are attached to an underwater surface

  7. http://www.youtube.com/watch?v=bZ1KDf3O-qU

  8. Polyps *Most common examples are the: Sea Anemone Hydra

  9. Medusa –bowl-shaped body plan • Adapted for a swimming life • Have mouths that open downward and tentacles that trail down

  10. Medusa—mythological character –will help you remember that the Medusa’s body shape is like a head with long hair

  11. Did you know? • Some cnidarians go through a polyp stage AND a medusa stage during their lives

  12. Obtaining Food • Polyps and medusas obtain food in the same way • Cnidarians use stinging cells to catch the animals they eat • The cell is a threadlike structure which has many sharp spines

  13. Obtaining Food • When the stinging cell touches the prey, the threadlike structure explodes out of the cell and into the prey. • Stinging cells paralyze the prey or release venom into it • When the prey becomes helpless, cnidarians use tentacles to pull the prey into their mouths

  14. Reproduction • Reproduce both a asexually and sexually • For most Cnidarians, budding is the most common form of asexual reproduction.

  15. Did you know that Cnidarians create coral reefs? • Coral polyps attach themselves to a solid surface at the beginning of their lives • After attaching to a solid surface, the coral polyp produces a hard, stony skeleton around its soft body • When polyp dies, its skeleton remains behind

  16. Coral Polyps

  17. Coral Reefs

  18. Coral Reefs

  19. Coral Reefs

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