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Phylum Cnidaria Anemones, Corals, Hydroids and Jellies.

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Presentation on theme: "Phylum Cnidaria Anemones, Corals, Hydroids and Jellies."— Presentation transcript:

1 Phylum Cnidaria Anemones, Corals, Hydroids and Jellies

2 Phylum Cnidaria Three classes: ► Class Anthozoa  Anemones  Corals ► Class Scyphozoa  True jellies ► Class Hydrozoa  Hydrozoans

3 Same body plan for all classes

4 Differences between Classes ► Some spend more time in the medusa or polyp form ► Can reproduce differently ► Can be colonial or solitary

5 Cnidaria Characteristics ► Symmetry: Radial ► Level of Organization: Tissue  Two cell layers (epidermis and gastrodermis) around a jelly-like substance (mesoglea)

6 ► Feeding:  Suspension feeding  Single opening (mouth/anus) into a gastrovascular cavity  All are carnivores  Have light sensing organs (ocelli) ► Excretion:  Wastes diffuse out of the cells into the water

7 ► Defense / Predation: Stinging Cells  All Cnidarians have stinging cells to protect themselves  A nematocyst is triggered with a hair cell  It ejects a harpoon or string with a toxin

8 Class Anthozoa ► Corals and anemones ► dominant polyp life stage

9 ► Anemones  Solitary: Usually one large polyp  Some can “swim” away if attacked  Some have symbiotic relationships, e.g. with clownfish or shrimp

10 ► Corals  Corals are colonial animals  Hard Corals ► Many polyps live on the outside of a calcium carbonate skeleton

11 ► Soft Corals  Many polyps live together but without the hard skeleton

12 Reproduction ► Both sexual and asexual reproduction  Asexual reproduction ► budding or fission (splitting in two)  Sexual reproduction ► Spawning ► Female eject eggs and males eject sperm into the water ► Timed to the phase of the moon!

13 Soft Corals

14 A hard coral close up

15 Hard Coral ► Table coral has a large flat top to take advantage of sunlight

16 Purple Stubby Coral ► Some grow in small finger-like projections

17 Staghorn Coral

18 Mushroom Coral

19 Brain Coral

20 Special relationships with algae ► Coral animals have a symbiotic relationship with a kind of algae called zooxanthellae ► Mutualistic relationship – they both benefit one another

21 ► Zooxanthellae  Does photosynthesis and gives the coral food (90% of the coral’s food is from here!) ► Coral  gives the zooxanthellae a stable home  gives the zooxanthellae nutrients from its waste

22 Colourful corals! ► The algae are responsible for the beautiful colours we see

23 Coral bleaching ► Zooxanthellae are very sensitive to temperature change and pollution ► If the temperature becomes too high, they leave the coral This is coral bleaching. Without the zooxanthellae, the coral will die.

24 Where would you rather dive? Here…

25 Or here…?

26 Class Scyphozoa ► Jellies ► Dominant medusa stage ► Some have both polyp and medusa stages

27 Coastal Jelly Life Cycle An ephyra larva

28 More images of the Jelly Life Cycle...

29 Powerful defenses ► Some jellies inject a very painful sting with their nematocysts ► Box jellies and sea wasps may be fatal

30 Class Hydrozoa ► Hydrozoans ► Colonial with specialized individuals to float, reproduce, defend or hunt. ► Some have both polyp and medusa stages ► Some have a skeleton of chitin

31 ► Portuguese Man O’ War  specialized polyps to float and sting

32 ► Hydra  lives in fresh water  has only a polyp stage  can reproduce by budding

33 Other Cnidarians ► Gorgonians like sea pens and sea whips are also in Phylum Cnidaria


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