1. Kingdom: Animalia
2. Habitat: aquatic, mostly marine.
3. Habit: solitary or colonial. Each individual is known as zooid.
4. Symmetry: radially symmetrical
5. Grade of organization: tissue grade of organization.
6. Germ layer: diploblastic, outer ectoderm and inner endoderm. Mesogloea separates these two layer
7. The body has a single opening called hypostome urrounded by sensor y tentacles.
8. Coelom: gastrovascular cavity or coelenteron.
9. Nematocyst: organ for capturing and paralyzing pray, present in tentacles
10. Nutrition: holozoic
11. Digestion is both intracellular and extracellular.
12. Respiration and excretion are accomplished by simple diffusion.
13. Circulatory system: absent
14. Nervous system: poorly develop
15. Many forms exhibit polymorphism ie. Polyp and medusa
16. Polyps are sessile, asexual stage
17. Medusa are free swimming, sexual stage
18. Metagenesis: asexual polypoid generation alternate with sexual medusoid generation
19. Reproduction: Asexual: by budding; Sexual: by gamatic fusion
20. Fertilization: internal or external
21. Development: indirect with larval stage
22. (Koilos: hollow, enteron: cavity)

Classification of Phylum Cnidaria/Coelenterata

The phylum coelenterate is divided into three classes on the basis of development of zooids:

• Class1: Hydrozoa
• Class2: Scyphozoan or Scyphomedusae
• Class3: Anthozoa or Actinozoa

 Class1: Hydrozoa

(Hydra; water; zoon: animal)

• Habitat: mostly marine, few are fresh water
• Habit: some are solitary and some are colonial
• Asexual Polyps is dominant form
• Medusa possess true velum
• Mesogloea is simple and acellular
• Examples: Hydra, Obelia, Physalia physalis (portuguese man of war), Tubularia

Class 2: Scyphozoa or Scyphomedusae

• Habitat: exclusively marine
• Habit: solitary, freely swimming
• Medusa is dominant and it is Large bell or umbrella shaped.
• Polyps is short lived or absent
• Mesogloea is usually cellular
• Examples: Aurelia aurita (Jelly fishe), Rhizostoma

Class 3: Anthozoa or Actinozoa

(Anthos: flower; zoios: animal “flower like animals”)

• Habitat: exclusively marine
• Habit: Solitary or colonial
• Medusa stage is absent
• Mesogloea contains fibrous connective tissue and amoeboid cells.
• Examples: Metridium (sea anemone), Telesto, Tubipora, Xenia

Phylum Cnidaria/Coelenterata: General Characteristic and Classification

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