veliger

Veliger is a larval stage in many mollusks, notably most gastropods and bivalves. It follows the trochophore stage in the molluscan life cycle and is defined by the appearance of the velum, a prominent, ciliated feeding and swimming veil. The velum is typically muscular and may have two to four lobes, used for capturing food particles and propelling the larva through the water.

During the veliger stage, the animal begins shell formation. In gastropods, the shell starts to form as early whorls or a cap-like cover, while in bivalves the mantle secretes the initial shell valves. The larva remains planktonic for varying periods, feeding on microalgae and using ciliary bands in addition to the velum for locomotion and nutrition. Metamorphosis to the juvenile snail or clam occurs when environmental cues trigger settlement to a benthic habitat; the velum is often reduced or lost as the adult body plan develops.

Ecology and significance: veligers are important for dispersal in marine environments, influencing population connectivity and life-history strategies. They are widely used in developmental biology and evolutionary studies to understand molluscan ontogeny. Fossil records of larval shells provide clues about ancient life cycles and early molluscan evolution. The term veliger derives from Latin velum, meaning veil, reflecting the distinctive velum that characterizes this stage.