The boring mechanism of Polydora websteri inhabiting Crassostrea virginica

The boring mechanisms of species of polydorid polychaetes are little understood due to lack of experimental evidence and direct observations. In the present studies the boring mechanism of adults and metamorphosing larvae of Polydora websteri was investigated by (1) inducing adults and larvae to settle against test substrates, (2) observing behavior in natural burrows and in “artificial blisters” composed of transparent “Pliobond” films surrounding Iceland spar substrates, (3) removing the giant setae of wormsprior to tests of boring, (4) applying the giant setae to substrates, and by (5) testing for production of acid.

All the layers of oyster shell, including conchiolin, were bored. Calcareous substrates andIceland spar were penetrated rapidly by adults without the assistance of the giant setae. Nor were these organs essential to the boring of a larva. A characteristic type of behavior involving close contact with the substrate during backwards and forwards movements and periods of immobility always preceded boring. The worms produced acid, probably some common product of metabolism, which can account for these results.