LIFE-HISTORY OF BOCCARDIA HAMATA (WEBSTER) ON THE EAST AND WEST COASTS OF NORTH AMERICA

¹ Department of Zoology and Entomology, University of Connecticut, Storrs, Connecticut 06268
² Department of Biology, Fresno State College, Fresno, California 93726

1. Larval development of the spionid polychaete, Boccardia hamata, is described from specimens followed from eggs and plankton isolates to young adult stages. Trochophore, 4-, 12-, 13- and 19-setiger stages are illustrated.

2. Eggs are deposited in an egg string within the Boccardia burrow. Development within the string proceeds to the 6-setiger stage at which stage the larvae are released to the plankton. Pelagic larvae grow to the 16- to 19-setiger stage before settling and metamorphosing. Length of pelagic life is estimated to be about three weeks.

3. Larval development of this species on both east and west coasts is identical except for slight variations in pigmentation and ventral ciliation on the third setiger. The most important difference between the larvae is in larval behavior at the time of metamorphosis. West coast larvae metamorphose readily on a variety of substrata and are unable to delay metamorphosis beyond the 19-setiger stage. East coast larvae are much more selective in choosing a substratum and can delay metamorphosis for more than two months. It is suggested that these behavioral differences reflect habitat differences of the adults on the two coasts.