Organisms associated with burrowing whelks of the genus <i>Bullia</i>

Abstract

Organisms found associated with the psammophilic neogastropod Bullia include hydroids, a boring sponge and algae which grow on, and burrow into, the shell. The shell may also be the recipient of the egg capsules of other species of gastropods. Peridinian ciliates are commonly found attached in some numbers to the tentacles and an occasional rotifer occurs on the soft parts of the animal. The gut is rich in bacteria, some of which are symbiotic, Digenetic trematode larvae are the mosl common internal parasites and larval cestodes also occur. Preliminary descriptions are given of two apparently new trematode larvae and of a cestode cysti-cercoid. A nematode worm is occasionally present in the gut. The absence of external parasites is noted and it is suggested that the shells of the whelk represent a refuge for smaller organisms or their eggs in an unstable environment lacking geological diversity.