Question

Write the characteristics of Phylum Cnidaria.

No copied answers please.

Answer 1

These are mostly marine and a few like hydra live in fresh water

Many are colonial (Eg: Corals). Some are solitary (Eg: sea anemone)

They are diploblastic and show tissue grade of organization

The body is radially symmetric but sea anemones show biradial symmetry

Polyp and medusa re the two different forms of cnidarians. Polyp is hydroid form which is sessile with mouth-up orientation. Medusa is umbrella or bell shaped with mouth down orientation. It swims by constricting the bell.

hope helps you ❤️

Answer 2

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$\textbf{CNIDARIA or COELENTRATA}$


Phylum Cnidaria also called Coelentrata. This name of Cnidaria due to single cavity 'coelenteron'.

→ The Cnidarian have tissue but don't have organ or organ system. That's why they posses tissue level of organization.

→ They are Radially symmetry and Diploblastic.

a) Radial Symmetry :- In which body can be divided into two equal halves by any plane passing through the centre from top to bottom.

b) Diploblastic :- Organsims in which cells are arranged into endoderm and ectoderm layers are called Diploblastic animals.

→ No separate body cavity or coelom.

→ They have single aperture mouth but not anus. They have incomplete digestive system.

→ They respire through body surface by diffusion.

→ They excrete through body surface by diffusion.

→ Segmentations are absent in them.

→ Tentacles are present in them which acts as appendages.

→ They are aquatic, mostly marine and free living animals.

→ They reproduce by both sexually and asexually.

→ Ex :- Sea-pan, Sea-fan, Brain coral etc.
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