Swimming behaviour of the larvae of Pecten maximus (L.) (Bivalvia)

Abstract

Laboratory observations indicate that larvae of Pecten maximus (L.) pass through three phases of swimming behaviour before metamorphosis. Trochophores and early veligers generally swim upwards and, in shallow containers, tend to accumulate at the surface. Their swimming cilia beat without interruption so swimming is continuous. After 3 days of development, pauses in ciliary beating occur intermittently and the veliger becomes capable of withdrawing into its shell. It alternately swims up a vertically orientated spiral and sinks. This type of swimming behaviour is also displayed by the pediveliger, but this larva also periodically swims close to, or crawls on, the substratum. The tendency to accumulate at the surface becomes less pronounced as larvae grow older. By the pediveliger stage it is replaced by an increasing tendency to accumulate close to the substratum.