‘An enteropneust's nest’: Results of the burrowing traits by the deep-sea acorn worm Stereobalanus canadensis (Spengel)

The burrowing enteropneust Stereobalanus canadensis occurs in abundances of 8-24 specimens per m2 in the deep-sea benthos of the Norwegian Sea. Highest numbers are correlated with dense burrow systems where the sediment surface is slightly raised as a mound. A burrow system consists of several horizontal galleries of dichotomously branched burrows, 6 mm in diameter, down to c. 10 cm depth and connected with each other by vertical shafts. 'An enteropneust's nest' is introduced as a term denoting the aggregation of S. canadensis in such a burrow system below a mound resulting in considerable transport of particles and exchange of chemical constituents in the sediments. Faeces are deposited as small elongated pellets and in lots of up to 1300 in numbers in a burrow system. This suggests that the inhabitants of 'an enteropneust's nest' have a common faecal deposit.