Description
The veliger is the characteristic larva of the gastropod, bivalve and scaphopod taxonomic classes. It is produced following either the embryonic or trochophore larval stage of development and is sometimes referred to as a D-stage larva. This stage in the life history of these groups is a free living, planktonic organism that potentially enhances dispersal to new regions far removed from the adult mollusks that produced the larvae.
The general structure of the veliger includes a shell that surrounds the visceral organs of the larva (e.g., digestive tract, much of the nervous system, excretory organs) and a ciliated velum that extends beyond the shell as a single or multi-lobed structure that is used for both swimming and particulate food collection. The larva may have or may develop a foot that will be used by the newly settled veliger as it moves about and searches for an appropriate place to metamorphose, and then subsequently is used by the juvenile for benthic locomotion. The velum and foot of the veliger can be retracted into the shell for the protection of these structures from either predatory or mechanical damage.
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