CHARACTERS AND AFFINITIES OF HEMICHORDATES.
Definition and Introduction Hemichordates is an independent phylum of marine invertebrates closely related to Echinodermata. They were previously classified as a subphylum of Chordata. Members exhibit the following key features: - Enterocoelous coelom : Coelom develops through enterocoely in three compartments (protocoel, mesocoel, metacoel). - Pharyngeal gill slits : Used for filter feeding. - Stomochord: A buccal diverticulum, initially mistaken for a notochord. - Body division: Vermiform structure with three regions – proboscis, collar, trunk. Examples include Balanoglossus, Saccoglossus, and Glossobalanus, classified under Class Enteropneusta . Affinities with Chordata Similarities to chordates include: - Pharyngeal gill slits - Dorsal hollow nerve cord in some species Objections to Inclusion in Chordata: ...