Phylum Hemichordata
GENERAL CHARACTERS
§ It is a small group of animals, which include about 90 species.
§ They are soft-bodied animals, which usually live in shallow “U”
shaped burrows in the sandy or muddy sea bottom.
EXTERNAL FEATURES
§ They are cylindrical or vase shaped animals, bilaterally
symmetrical and lack any segmentation.
§ They may be solitary or colonial and usually range between a few
millimeter and 250 cm in length.
§ Sexes are separate in hemichordates.
INTERNAL FEATURES
§ Circulatory system is open and coelom is divided into three
chambers.
§ A dorsal and a ventral nerve cord are present.
LARVA
Tornaria larva
EXAMPLE
Balanoglossus,
Acron worm etc.
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