NEET BIOLOGY

Detailed explanation-1: -Obelia is a genus of hydrozoans, a class of mainly marine and some freshwater animal species that have both polyp and medusa stages in their life cycle. Hydrozoa belongs to the phylum Cnidaria, which are aquatic (mainly marine) organisms that are relatively simple in structure with a diameter around 1mm.

Detailed explanation-2: -So, the correct answer is ‘Hydra’

Detailed explanation-3: -The obelia’s body has two kinds of filaments which are vertical hydrocaulus and horizontal hydrorhiza. Obelia’s life cycle begins as hydroid polyps. Hydroid polyps are small, immobile animals that have tentacles and stalks. Their structure resembles sea anemones; hence they are also called sea furs.

Detailed explanation-4: -Obelia, genus of invertebrate marine animals of the class Hydrozoa (phylum Cnidaria). The genus, widely distributed in all the oceans, is represented by many species. The animal begins life as a polyp-a tentacled, stalklike form resembling a small sea anemone attached to the ocean bottom or some other solid surface.

Detailed explanation-5: -Obelia is a genus of invertebrate marine organisms whose members exist in alternate generations as polyps and medusae. Part of the phylum Cnidaria, Obelia species are related to sea anemones, corals, freshwater hydra, and jellyfish.