Question

Write the general characters of the phylum cnidaria.

Answer 1

• The cnidaria are aquatic, radially symmetrical and diploblastic.
• The tentacles have stinging cells called cnidocytes or cnidoblasts or nematocysts. 
• They exhibit tissue level of organisation.
• They have a central gastrovascular cavity called coelenderon.
• Digestion is by both extracellular and intracellular. 
• Alternation of generation is seen in cnidarians which have polyp and medusa forms.
• Development is indirect with planula larva e.g. Physalia.