Balanoglossus belongs to class Enteropneusta, phylum Hemichordata. It is a
marine animal, widely distributed in all seas of the world. It lives in burrows in
inter-tidal zone and shallow water, though some species may live in somewhat
deeper zones.
The presence of Balanoglossus can be detected by the odour emitted by them,
which resembles that of idoform. An individual lives in a U-shaped burrow
excavated by the proboscis.
U-shaped burrow of Balanoglossus
External Features of Balanoglossus:
Balanoglossus is a soft-bodied, cylindrical, worm-like animal. The size in
different species varies from 2 to 3 mm to 2.5 meters. Most of the surface is
ciliated.
The body is divisible into three regions, proboscis or protostome, collar or
mesostome and trunk or metastome.