Q. Scheme of Classification of phylum hemichordate?
These are about 90 species of hemichordates. All are marine and live in the open sea or in muddy sediments. Hemichordata were once included in the phylum Chordata and were grouped as invertebrate (backboneless) chordates under 'protochordates' (first chordates). They have a dorsal nerve cord, often hollow, developed from the dorsal epidermis. The longitudinal stiffening stomatochord is no more thought to be the homologue of the notochord and this distinction justified the separation of the hernichordata from the chordata.