Eastern lampmussel

Distribution and Habitat

The eastern lampmussel ranges from South Carolina north to the St. Lawrence River Basin. In New Jersey, the species is known from locations in the Paulins Kill, Kymer Brook, Ramapo, Pequannock, Wallkill, and Whippany Rivers as well as several lakes. The eastern lampmussel is found in a variety of habitats, though it is probably more prevalent in lakes in NJ than in flowing waterways. It is reported to prefer medium to coarse sands. Reported fish hosts include bluegill, pumpkinseed, longear sunfish, large and smallmouth bass, white perch, yellow perch, black crappie, bluntnose minnow, and rock bass.

Diet

Adult freshwater mussels are filter-feeders. They strain plankton (microscopic plants and animals), bacteria and other particles from the water column. The larval stage of the freshwater mussel, known as glochidia, are external parasites and feed on a host (usually a fish).

Life Cycle

Although many species of mollusks are hermaphrodites (one individual has both male and female reproductive organs), freshwater mussel sexes are generally separate. During spawning, males release sperm directly into the water. If a mature female happens to draw-in the sperm through its siphon, the eggs which are contained within her body will be fertilized. The eggs then develop within the female’s gills into the larval stage of the mussel known as “glochidia”. This period of larval development within the female’s body may last a few days to several months. At the end of this stage, up to several million glochidia will be expelled into the water through the female’s exhalent siphon.

Glochidia are microscopic and have a thin shell with two valves. Once released from the female, glochidia must find a host (usually a specific species of fish) on which to attach. Each species of freshwater mussel has its own specific species of fish that can serve as a host for the glochidia. The glochida effectively become a parasite on the fish, attaching to the gills, scales, fins or even eyes of the host fish. While attached to the fish, the glochidia feed on them, much like a flea or tick feeds on terrestrial mammals. If the glochidia do not attach themselves to a host fish, they will die.

While attached to the host fish, the glochidia go through a metamorphosis, transforming into a juvenile mussel which looks like a much smaller version of the adult. After anywhere from 6 to 160 days, the juvenile mussel will fall off of the host fish and begin its life in the bottom of the water body. If the appropriate substrate is available, it will burrow into the bottom sediment. Juvenile mussels spend their first year of life beneath the substrate.

Growth of the mussel is most rapid while it is young. The average age at which freshwater mussels become sexually mature is six years. Once a freshwater mussel reaches maturity, its chances for survival increase dramatically. Some species may live as long as 100 years or more.

Although very slow-moving, freshwater mussels are capable of moving along the substrate using their powerful foot. A mussel “track” can sometimes be seen in the mud or sand next to a mussel which has recently moved. During the winter in New Jersey, freshwater mussels will burrow into the sediment and enter a period of dormancy.

Many small aquatic animals will feed on the mussel glochidia. Adults may be eaten by raccoons, muskrats, otters, bears, herons, some waterfowl, some turtles, and large fish such as sturgeon.