Question

Identify the phylum having following characteristics: multi-cellular, radially symmetrical, aquatic, hollow gut.

Answer 1

• Radially symmetrical, diploblastic multicellular animals with a tissue grade of organisation.

• Aquatic, freshwater or marine solitary or colonial forms which may be free swimming or sedentary.

• Body has a mouth at the oral end which leads into a spacious cavity called gastrovascular cavity or coelenteron.

• Presence of long, hollow structures called tentacles used for locomotion and food capturing.

• Presence of peculiar type of cells called cnidoblasts, nematocysts or stinging cells in the ectoderm, especially in the tentacles, used for offence and defence.

• Digestion is both intracellular and extracellular.

• Respiration and excretion by simple diffusion.

• Presence of a network of nerves spread all over the body.

• Many forms exhibit polymorphism, wherein different types of individuals are present in a colony for different functions. These individuals are called Zooids.

• Reproduction asexually (external budding) or sexually (formation of gametes).