The Burrow of an Enteropneust

Abstract

STIASNY described how Balanoglossus clavigerus lives in a U-shaped burrow, which is characterised by a regular funnel on the surface at the anterior end of the animal, with the coils of fæces at the posterior end. His illustration has been reproduced in several books. Morgan has also found similar funnels and masses of fæces in the case of another species of Balanoglossus and it is probable that all species of this genus inhabit similar burrows. Other species of Enteropneust a, for example, those belonging to the genera Glossobalanus and Ptychodera, live among the roots of seaweeds, under stones or in the sand in irregularly-shaped tubes of sand-grains, etc., cemented together by slime. It is known that most species of Saccoglossus (Dolichoglossus) prefer to live in a black muddy soil, but Davis is the only author who has described a special burrow for Saccoglossus pusillus, and according to his figure this burrow is irregularly formed.