Mollusk Glossary
What is a trochophore? Look here to find a definition for this word and other terms associated with mollusks.
Adductor muscle
Muscle(s) in bivalves attached to both shells (valves); adductor muscles pull the two shells together (closes the shells). An elastic hinge pushes the shells apart (opens the shells).
Bivalve
A mollusk with two valves, or shells, joined together by a hinge. Members of Class Bivalvia (“two valves”) can be found in freshwater and marine environments. Examples include clams, scallops, oysters, and mussels.
Cephalopod
A marine mollusk with a well-developed head surrounded by a ring of eight or more arms. Members of Class Cephalopoda (“head-footed”) have a well-developed nervous system and propel themselves by jetting water through a siphon. They include pelagic and bottom dwellers. These animals maybe shell-less such as the octopus, possess an internal shell (squid and cuttlefish), or they may have an external shell (chambered nautilus).
Filter feeder
An animal that filters phytoplankton from the water for food. Most filter-feeding mollusks pump water across their gills, which act like fine-screen filters. A pair of siphons (inhalant and exhalent) allows burrowing bivalves to reach the water column without leaving the safety of their burrow.
Gastropod
A mollusk with well-developed foot, head, and body. Class Gastropoda (“stomach-footed”) is the largest group of mollusks and can be found in terrestrial, freshwater, and marine habitats. Members of this group may be shell-less (slugs and sea hares), or typically possess a spiral-shaped shell (snails or conch).
Harvest areas
Regions where recreational fishing is allowed (open) or prohibited (closed) during certain times of the year.
Hermaphrodite
Having both female and male reproductive organs.
Introduced species
A non-native species that is deliberately introduced into an area or inadvertently brought into a region due to human activities.
Invasive species
An introduced species that threatens economic or environmental harm to ecosystems, habitats, or species. Only some introduced species become harmful.
Landing
The act of bringing an animal (fish, scallop, lobster, etc.) ashore.
Metapopulation
A population composed of smaller, isolated populations.
Non-native species
A species that is not indigenous, or naturally occurring, in a region.
Pelagic organism
An organism that lives in open water rather than on the bottom.
Protandric
Develops male reproductive organs initially and female reproductive organs at a later time.
Spat
Juvenile bivalve.
Spawning organism
An animal that reproduces by expelling eggs or sperm (or both eggs and sperm) into the surrounding water resulting in external fertilization.
Trochophore
A very early larval stage of mollusks (and some worms). The body is ringed by a band of cilia.
Veliger
A specialized term for molluskan planktonic larvae. Although they do not always have the same appearance as in adults, the shell and most organs can be seen.
