Presentation on theme: "Phylum Cnidaria: Jellies, anemones, corals and hydroids"— Presentation transcript:
1 Phylum Cnidaria: Jellies, anemones, corals and hydroids CnidariansPhylum Cnidaria:Jellies, anemones, corals and hydroidsMrs. Covington: Marine Biology
2 Basic Facts Simple:slightly more complex than sponges Radial Symmetry: no head, front or back; looks the same from every sideAbundant: 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 nematocystsNEMATOCYST: 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 colloidLayer 2: ENDODERM- Digestion and absorption of food
5 Body Parts (sides)OralAboralPart 1: Oral- Digestive cavity, sac-like, the open end is the mouthPart 2: Aboral- Tentacles located around mouth, used to catch food and assist in movement
6 Diagram: Showing oral and aboral parts BOTTOM VIEW OF BODYOral (mouth area)Aboral (tentacle area)
7 2 Body Forms (Stages)POLYP- mouth & tentacles face up, most are sessileMEDUSA- mouth & tentacles face down, free swimming
8 Jelly ReproductionJellies 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 fragmentationJellies are either male or female and reproduce sexually by releasing egg & sperm into the water.Repro
9 Coral (& Hydroid) Reproduction Asexually by budding or fragmentationSexually 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 Reefs1. 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 ReefBarrier ReefAtollsPatch Reef
16 Conditions for Reef Growth Hard SurfaceShallow 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 coralliteCorals feed mainly on zooplankton, with the help of zooxanthellae
18 Competition, Predation, & Disease Corals may be overgrown by a different creature competing for space & lightSome creatures attack coral, destroying itSome creatures eat coral but don’t destroy it, others graze heavily
19 Coral AggressionCorals 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 recoverBlack-Band Disease caused by Cyanobacteria, kills coral as it growsPollutionNatural death by unknown causes
21 Man using dynamite to either blow up coral to sell or to kill reef fish…very, very bad!