mollusk cephalopod

The Atlantic brief squid, Lolliguncula brevis, tolerates the variable and shallow conditions of the Chesapeake Bay very well, although little is still known about the distribution of this species throughout the Bay. Generally, however, this little squid can live in low salinities and survive the broad range of environmental conditions that the Bay presents.

The brief squid is a small mollusk in the Cephalopod family (meaning ‘head-footed’).

• The family includes animals whose ‘foot’—divided into several armlike appendages—is situated close to the animal’s head.
• The squid is a freeswimming mollusk whose ‘shell’ is actually an uncalcified shell vestige that is embedded within the animal’s mantle.
• Like other squid, the brief squid swims with its ventral surface forward, and trails its elongated dorsal surface. It also relies on its capacity to retreat speedily from dangerous situations, rather than a hard shell, for protection.
• The feather-shaped shell is buried inside the muscular mantle, the squid’s swimming organ.

  Photo courtesy of Roger T. Hanlon, Senior Scientist at Marine Biological Laboratory

  Photo courtesy of Ian Bartol, Assistant Professor, Old Dominion University

• The mantle spreads into triangular ‘fins’ at the rear end, which serve as swimming stabilizers and help the animal to steer.
• At the other end, a sort of collar surrounds the ‘neck’, between the squid’s head and viscera.

A muscular tube or funnel, which is part of the animal’s foot, projects under the head. When the squid is relaxed, water enters the cavity around the collar, and when the mantle contracts, the collar seals and water is ejected through the funnel. When the squid must move quickly to obtain prey, it contracts its mantle and sends a jet of water through the funnel, which is bent backward, and the jet pushes the squid forward, toward its prey. Under threat, the squid directs its funnel forward, and shoots itself backward with lightning speed. It also may emit an ink cloud as a sort of smokescreen to distract predators.

Squid species have nervous systems that contain some of the largest neurons found in nature. In a squid, the axon of the nerve cell is proportionately very large, unlike axons in mammals, which can be seen only under magnification. Scientists have used squid axons to study nerve impulses in an effort to understand such mammalian diseases as multiple sclerosis, Alzheimer’s and Parkinson’s.

Life Cycle and Range

• Brief squid lives in inlets and estuaries, from Maryland to Florida and Texas and Mexico; from the West Indies to Uruguay.
• Like other cephalopods, brief squid have separate sexes; the females deposit gelatinous masses of yolky eggs which hatch as fully formed, miniature versions of the parent.

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Last modified: 06/02/2005