Cnidarians (; ->->->

1. Cnidarians (; ->->-> By: Cristina Ortiz & Angie Sevilla

2. What are Cnidarians? • Cnidarians are part of the Phylum Cnidaria • They are carnivorous animals that contain stinging tentacles • Stinging cells are called cnidocytes • Within each cnidocytes is a nematocyst

3. Body Plan Each has: • Body wall that surrounds an internal space called a gastrovascular cavity • The gastroderm is the inner lining of the gastrovascular cavity, where digestion takes place • The epidermis is the outer layer of cells • The mesoglea is a layer that lies between these two tissues Two stages: Polyp and Medusa Polyp: Cylindrical body with arm-like tentacles Mouth points upward Medusa: Motile, bell-shaped body Mouth on the bottom

4. Cnidarian’s Body Plan Polyp on the left & Medusa on the right

5. Reproduction • Polyps: Asexually by budding (two types) • 1) Swelling on the side of an existing polyp & grows into a new polyp • 2) Polyps produce tiny medusas that separate and become new individuals • Sexual reprodction: External fertilization • Takes place outside the female’s body • Female releases eggs into the water and male releases sperm • Zygote grows into a free-swimming larva • Larva attaches to a hard surface and develops into a polyp • Polyp buds and releases a medusa

6. Groups of Cnidarians Sea Anemones and Corals: Sea Anemones live at the depth of the ocean & use nematocysts to catch a variety of marine organisms Coral Polyps are colonial and grow together in large numbers, while limestone is created. Reproduce sexually and asexually Jelly Fish: • Class Scyphozoa • Scyphozoans means “cup animals” • Live their lives primarily as medusas • Can be quite large • Reproduce sexually Hydras: • Hydras lack a medusa stage • Reproduce asexually by budding or sexually by producing eggs & sperm • Get nutrition from capturing, stinging, and digesting small prey

7. Human Uses & Effects Human Uses: • Medicine • Food Effects: • Can be toxic to humans • Stinging structures