Atlantic Bay Scallop (Argopecten irradians amplicostatus)

Description

The Atlantic bay scallop has a valve length of 2.5 to 2.8 inches (60 to 70 mm). It has nearly identical fan-shaped shells with 17 to 20 ribs on each shell. Shell color varies.

Life History

The Atlantic bay scallop feeds by absorbing and ingesting floating detritus (dead and decomposing plant and animal matter). Starfish, wading birds, seagulls, pinfish, lightning whelks, cow-nosed rays, crabs, and humans are among its numerous predators. Atlantic bay scallop reaches sexual maturity at one year. Spawning season begins in August and lasts through October. Females release 100,000 to 1 million eggs. Within 29 days after hatching, the juvenile stage is reached. Within 35 days, the scallop resembles a small adult. Its lifespan is less than two years.

As juveniles, scallops will attach themselves to a surface suspended off the bottom with special adhesive threads called byssal threads. As adults, scallops move from one place to another by quickly "clapping" their valves together and ejecting water, creating a type of "jet propulsion". Sometimes scallops migrate in mass.

Scallops are hermaphrodites (can be both male and female). A single scallop will generally release sperm (as a male) before it releases eggs (as a female). This reduces the chance of it fertilizing itself. Natural occurrences such as red tide (a harmful algal bloom) can kill millions of adult and larval bay scallops. Scallops grow at a faster rate during the warmer months when food is readily available. They have a series of blue eyes around the mantle (the tissue that secretes the shell). Although they are weak, the eyes help scallops identify predators.

Habitat

Atlantic bay scallops prefer bays where salinity is high and seagrass meadows are common, especially habitat covered with eel grass (Zostera marina) and/or shoal grass (Halodule wrightii). They are most commonly found in calm waters 0.3 to 0.6 meters at low tide.

Distribution

In Texas, the Atlantic bay scallop is found from Galveston down to the Laguna Madre along the Texas Gulf Coast.

Other

The destruction of seagrass areas as a result of dredging and development has resulted in the decreased abundance of the bay scallop. This tasty seafood is collected by hand, with dip nets, by raking and dredging. Scallops can only be harvested from areas approved by the Texas Department of Health-Seafood Safety. Because they are filter-feeders, Atlantic bay scallops are studied to test the effects of petroleum spills in coastal habitats.