21.Which of the following is not a fish- A. Star fish B. Dog fish C. Angel fish D. Saw fish
Option A Starfish belongs to phylum echinodermata. A true fish belongs to the phylum Chordata and vertebrata, so they have a backbone. They have had notochord during the embryonic development which is now replaced by the backbone. They belong to class pisces and have a single chambered heart. They breathe through gills and have fins for propulsion.
