1. Phylum Cnidaria: Jellies, anemones, corals and hydroids
Cnidarians
Phylum Cnidaria:
Jellies, anemones, corals and hydroids
Mrs. Covington: Marine Biology

2. Basic Facts Simple:slightly more complex than sponges
Radial Symmetry: no head, front or back; looks the same from every side
Abundant: Nearly 10,000 species
(mostly found in warm, marine habitats)

3. Body Layers Body wall consists of 2 layers separated by jelly
Layer 1: ECTODERM- muscle, nerve, or thread cells called nematocysts
NEMATOCYST: contains stinging cells (cnidoblasts)with neurotoxic poison, used for defense and food capture.

4. Body Layers cont…
Layer 1 and 2 are separated by the Mesoglea, a non-cellular, gel colloid
Layer 2: ENDODERM- Digestion and absorption of food

5. Body Parts (sides)
Oral
Aboral
Part 1: Oral- Digestive cavity, sac-like, the open end is the mouth
Part 2: Aboral- Tentacles located around mouth, used to catch food and assist in movement

6. Diagram: Showing oral and aboral parts
BOTTOM VIEW OF BODY
Oral (mouth area)
Aboral (tentacle area)

7. 2 Body Forms (Stages)
POLYP- mouth & tentacles face up, most are sessile
MEDUSA- mouth & tentacles face down, free swimming

8. Jelly Reproduction
Jellies are either male or female and reproduce sexually by releasing sperm into the water.
Corals (& hydroids) may reproduce sexually by releasing egg and sperm or asexually by budding or fragmentation
Jellies are either male or female and reproduce sexually by releasing egg & sperm into the water.
Repro

9. Coral (& Hydroid) Reproduction
                                 
Asexually by budding or fragmentation
Sexually by releasing egg and sperm

10. Practice Body Parts (Sides)
Practice Body Forms (Stages)

11. CORAL REEFS: The most densely populated ecosystem on earth!

12. Types of Reefs
1. Fringing Reef- Grows close & parallel to shore as a narrow band (inner reef is flat, outer reef is sloped)
*Barrier Reef- Farther off shore than fringing & separated by a lagoon. Parallel to shore, may be exposed at low tide

13. Andros Barrier Reef: 140 miles long! (3rd longest in the world )
Visible from east shore of Andros on the horizon…look for waves breaking.

14. Reef types cont…
Atolls- Ring of reef with steep outer slopes enclosing a shallow lagoon
*Patch Reef- Small, isolated growths of reef that usually form between fringing or barrier reef and the shore.

15. Illustration of Reef Types
Fringing Reef
Barrier Reef
Atolls
Patch Reef

16. Conditions for Reef Growth
Hard Surface
Shallow Water (165 ft. or less)
Warm Water (about 68° F)
Clear Water
*Coral can grow ½ in. per year in good conditions!
*Which side of Andros will have coral?

17. Importance of Algae to Coral
Coral exhibits mutualistic symbiosis with Zooxanthellae Algae (dinoflagellates)
Photosynthetic Dinoflagellates nourish corals with sugars which help them produce limestone corallite
Corals feed mainly on zooplankton, with the help of zooxanthellae
                                

18. Competition, Predation, & Disease
Corals may be overgrown by a different creature competing for space & light
Some creatures attack coral, destroying it
Some creatures eat coral but don’t destroy it, others graze heavily

19. Coral Aggression
Corals will send out filaments to attack and digest another coral in its way! This would be an example of competition for space (light).
                                               

20. Competition, Predation, & Disease cont…
Coral bleaching: If stressed, corals expel algae causing loss of color. If algae are regained, it may recover
Black-Band Disease caused by Cyanobacteria, kills coral as it grows
Pollution
Natural death by unknown causes

21. Man using dynamite to either blow up coral to sell or to kill reef fish…very, very bad!

22. THE END