1. Diversity of Life – Animals (jellyfish, anemones, corals)
CNIDARIA
(jellyfish, anemones, corals)

2. A Phylogeny of the Animal Phyla
Porifera
No true tissues
Cnidaria
radial symmetry
diploblastic
Ctenophora
Platyhelminthes
Acoelomates
Rotifera
Pseudocoelomates
Nematoda
Nemertea
Mollusca
Protostomes
true tissues
Annellida
Arthropoda
Bilateral symmetry
triploblastic
Bryozoa
Lophophorate phyla
Body cavity
Phoronida
Coelomates
Brachiopoda
Echinodermata
Chordata
Deuterostomes

3. Cnidaria - jellyfish, corals, anemones
Description
Animals that are
• diploblastic
• gastrovascular cavity
• single opening (mouth + anus)

4. Cnidaria - jellyfish, corals, anemones
Jelly fish Anemones Corals
Hydroids

5. Cnidarians are diploblastic animals (2 germ layers)
There can be two
or three
Ectoderm
Mesoderm
Endoderm
Diploblastic
Triploblastic

6. Cnidaria - Body plans
Both forms are present in the life cycles of most cnidarians
POLYP
MEDUSA

7. Gastrovascular cavity
Cnidaria - Body Plans
Mouth/anus
Epidermis (=ectoderm)
Mesoglea
Gastrodermis (=endoderm)
Tentacle
Gastrovascular cavity
Tentacle
Mouth/anus
POLYP MEDUSA
Note: No Mesoderm

8. Cnidaria - Body Plans Epidermis (ectoderm) Mesoglea
Gastrodermis (endoderm)

9. Cnidaria - Body Plans Interstitial cells Cnidocyte
Epitheliomuscular cell
Neuron
Epidermis
Muscle fibrils
Mesoglea
Gastrodermis
Enzymatic gland cell
Nutritive muscle cell

10. Cnidaria - Body Plans Epidermis
Epitheliomuscular cells – form outer covering of animal
- contractile
Interstitial cells – produce other kinds of cells including sperm and egg
Cnidocytes – feeding cells
Neurons – nerve cells: part of the nerve net
Muscle fibrils – contractile fibres – allow movement
Cnidocytes – feeding cells
Neurons – nerve cells: part of the nerve net
Gastrodermis
Nutritive muscle cell - takes in food from gastrovascular cavity
Enzymatic gland cell - secretes enzymes to ‘pre-digest’ food

11. Cnidaria - Body Plans
Mesoglea

12. Cnidaria - Body Plans Mesoglea
Fibres of collagen & mucopolysaccharides

13. Cnidaria - Feeding

14. Cnidaria - Feeding

15. Cnidaria – Nerves and Movement

16. Cnidaria - Types of Cnidarians
Hydrozoa - Hydra, Portuguese-man-of-war, fire corals
- both polyp and medusa in life cycle

17. Cnidaria - Types of Cnidarians
Hydrozoa - Hydra, Portuguese-man-of-war, fire corals
- both polyp and medusa in life cycle
gastrozooid
gonozooid
dactylozooid

18. Cnidaria - Types of Cnidarians
Hydrozoa - Hydra, Portuguese-man-of-war, fire corals
- both polyp and medusa in life cycle

19. Cnidaria - Types of Cnidarians
Hydrozoa - Hydra, Portuguese-man-of-war, fire corals
- both polyp and medusa in life cycle

20. Cnidaria - Types of Cnidarians
Hydrozoa - Hydra, Portuguese-man-of-war, fire corals
- both polyp and medusa in life cycle
Life Cycle

21. Cnidaria - Types of Cnidarians
2. Scyphozoa - jellyfish
-exist as a medusa - polyp stage is reduced

22. Cnidaria - Types of Cnidarians
3. Anthozoa - anemones and true corals
-exist as a polyp - medusa stage is absent

23. Cnidaria - Types of Cnidarians
3. Anthozoa - anemones and true corals
-exist as a polyp - medusa stage is absent

24. Cnidaria - Types of Cnidarians
3. Anthozoa - anemones and true corals
-exist as a polyp - medusa stage is absent
Eggs
Planula
Sperm
Adult colony
Primary polyp