Write an essay on the polymorphism in coelenterata?

Question: Write an essay on the polymorphism in coelenterata?

Polymorphism in Coelenterata

Polymorphism is the phenomenon of occurrence of more than one type of structurally and functionally different individuals within a population. It is an important feature of phylum Coelenterata, which includes aquatic or marine animals such as hydras, jellyfishes, sea anemones, and corals. Coelenterates have two main forms of individuals or zooids: polyps and medusae.

Polyps are tubular, sessile, and usually attached to a substratum by a pedal disc. They have a mouth surrounded by tentacles at one end and a blind end at the other. They are responsible for feeding, protection, and asexual reproduction.

Medusae are bowl- or umbrella-shaped, motile, and free-swimming. They have marginal tentacles and a mouth centrally located on a projection called manubrium on the lower concave surface. They are responsible for sexual reproduction.

Some coelenterates are monomorphic, meaning they have only one form of zooid, such as Hydra and sea anemone. However, most coelenterates are polymorphic, meaning they have more than two forms of zooids in a colony. The degree of polymorphism varies greatly in different groups of coelenterates.

For example, Obelia and Tubularia are dimorphic, having two types of zooids: gastrozooids for feeding and gonozooids for sexual reproduction. Hydractinia is polymorphic, having five types of zooids: gastrozooids for feeding, spiral dactylozooids for protection, tentaculozooids for sensory function, skeletozooids for spiny projections, and gonozooids for sexual reproduction.

Polymorphism in coelenterates is essential for division of labor among the individual zooids. Different functions are assigned to different forms. Polymorphism also helps in adaptation to different environmental conditions and survival of the colony.

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