Veliger

Veliger

A veliger is a larval stage in the life cycle of certain mollusks, particularly gastropods and bivalves. It is characterized by the presence of a distinct velum, a ciliated structure used for locomotion and feeding. The veliger stage is an important transitional phase in the development of these mollusks, as it marks the transition from a planktonic existence to a benthic lifestyle.

Anatomy and Development

The veliger larva typically has a well-defined head region, with a pair of eyes and a mouth surrounded by cilia. The velum, located on the dorsal side of the larva, is a thin, transparent structure that aids in swimming and capturing food particles. As the veliger grows, it undergoes a series of morphological changes, eventually developing into the juvenile form of the mollusk.

Feeding and Locomotion

The velum plays a crucial role in the feeding and locomotion of the veliger larva. The cilia on the velum create a current that draws in water and suspended particles, which are then directed towards the mouth for ingestion. This feeding mechanism allows the veliger to obtain nutrients necessary for its growth and development.

In terms of locomotion, the velum acts as a propeller, enabling the larva to move through the water column. By beating its cilia in a coordinated manner, the veliger can control its direction and speed of movement. This ability to actively swim allows the larva to disperse and explore its environment.

Importance in Mollusk Life Cycle

The veliger stage is a critical phase in the life cycle of mollusks, as it represents a transition from a free-swimming larva to a benthic juvenile. During this stage, the veliger undergoes metamorphosis, where it undergoes significant changes in its body structure and behavior. These changes prepare the larva for its settlement onto a suitable substrate, where it will continue its growth and development.

Examples of Veliger Larvae

Gastropods such as snails and slugs have veliger larvae. These larvae are typically planktonic and can be found in marine, freshwater, and terrestrial environments. Some well-known gastropod species with veliger larvae include the common garden snail (Helix aspersa) and the marine cone snail (Conus species).

Bivalves such as clams, mussels, and oysters also have veliger larvae. These larvae are usually planktonic and are released into the water column by adult bivalves for dispersal. Examples of bivalves with veliger larvae include the blue mussel (Mytilus edulis) and the Pacific oyster (Crassostrea gigas).

References

1. Smith, S. A., & Strathmann, R. R. (2008). Larval feeding and the acquisition of competence to settle and metamorphose in the nudibranch Phestilla sibogae. Biological Bulletin, 215(1), 98-108.

2. Young, C. M., & Chia, F. S. (1984). Larval development and metamorphosis of the gastropod Crepidula adunca. Marine Biology, 78(2), 157-168.

See Also

• Gastropod
• Bivalve
• Metamorphosis
• Plankton
• Mollusk