BUOYANCY CHARACTERISTICS OF LANICE-CONCHILEGA (PALLAS) LARVAE (TEREBELLIDAE) - IMPLICATIONS FOR SETTLEMENT

For the first time, observations of the aulophore larvae of Lanice conchilega (Pallas) have been made in a sufficient depth of seawater for the displacement conditions to be similar to those in the field. The position and stability of the larva in the water column depend on the secretion of a mucus trail and not on the circulation of water between the body of the larva and the tube wall or on the density of the tube. The sinking rate is variable and depends on the behaviour of the larva which can sever its connection with the mucus trail or secrete another one very quickly. Once on the sediment the larva retains its ability to return to the water column; this suggests that the conditions which allow them to leave the substratum play as important a role in the settlement of larva on a specific substratum as the passive sinking rate does. © 1990.