THE FEEDING AND ECOLOGY OF TWO NORTH PACIFIC ABARENICOLA SPECIES (ARENICOLIDAE, POLYCHAETA)

¹ Department of Oceanography, University of Washington, Seattle, Washington 98105

1. A comparison of the habitats of two sympatric lugworms shows that Abarenicola pacifica lives in a muddier and more poorly sorted sediment than does A. claparedi vagabunda.

2. Both species, like Arenicola marina, are capable of suspension feeding, feed predominantly on surface rather than deep sediment, and integrate feeding and defecation into their irrigation cycle.

3. Respiration and sediment turnover rates indicate that Abarenicola claparedi vagabunda is more active than A. pacifica. Both species seem to need little (3-5%) of the organic carbon ingested.

4. Transplantation experiments suggest that physical factors rather than availability of food may limit A. pacifica to muddier sediment and that the distribution of A. claparedi vagabunda may be a result of larval settlement and survival.

5. It is proposed that this mode of feeding has been retained throughout lugworm evolution because the observed feeding behavior should have been successful throughout the range of lugworm habitats, and because of the probable lack of interspecific competition for food.