Lampsilis fasciola
wavy rayed lamp mussel
(Also: wavy-rayed lampmussel; wavyrayed lampmussel)

The wavy-rayed lampmussel is discontinuously distributed in the Great Lakes drainages. Historically it was found from Ontario to Alabama and Illinois to New York.

In Michigan this species is only found in Lake Erie drainages. (Burch, 1975; van der Schalie, 1945)

The wavy-rayed lampmussel is rarely found in smaller, upstream creeks or in downstream areas of larger rivers. In the Huron River this species was found in more or less solid sand and gravel bottom in riffles and rapid waters. (Cummings and Mayer, 1992; van der Schalie, 1938; Watters, 1995)

The wavy-rayed lampmussel is up to 8 cm (4 inches) long , and is rounded or oval in shape. The shell is usually fairly thick, and compressed or inflated in females. This species is sexually dimorphic. The anterior end is rounded, the posterior end bluntly pointed in males, and slightly more rounded in females. The dorsal margin is straight and the ventral margin is curved.

Umbos are low, being raised only slightly above the hinge line. The beak sculpture has three to five double looped ridges.

The periostracum (outer shell layer) is smooth, yellow to yellow-brown, with thin wavy green rays. Older specimens tend to be more brown.

On the inner shell, the left valve has two pseudocardinal teeth, which are triangular, short, thick and divergent. The two lateral teeth are straight to slightly curved and short. The right valve has one triangular, short, thick pseudocardinal tooth. The one lateral tooth is short and straight to slightly curved.

The beak cavity is moderately deep. Although the nacre is white, it is iridescent at the posterior end.

In Michigan, this species can be confused with the pocketbook. The pocketbook is generally more round and is larger, so growth rings are farther apart. Green rays are not as wavy and are wider. The pocketbook also has a heavier hinge. (Cummings and Mayer, 1992; Stagliano, 2001; Watters, 1995)

Fertilized eggs are brooded in the marsupia (water tubes) up to 11 months, where they develop into larvae, called glochidia. The glochidia are then released into the water where they must attach to the gill filaments and/or general body surface of the host fish. After attachment, epithelial tissue from the host fish grows over and encapsulates a glochidium, usually within a few hours. The glochidia then metamorphoses into a juvenile mussel within a few days or weeks. After metamorphosis, the juvenile is sloughed off as a free-living organism. Juveniles are found in the substrate where they develop into adults. (Arey, 1921; Lefevre and Curtis, 1910)

The age of mussels can be determined by looking at annual rings on the shell. However, no demographic data on this species has been recorded.

Mussels in general are rather sedentary, although they may move in response to changing water levels and conditions. Although not thoroughly documented, the mussels may vertically migrate to release glochidia and spawn.

A female Lampsilis fasciola has a distinct mantle flap which resembles a minnow or darter. The mimic fish lures its host fish, which chews on the flap and breaks the membrane of the gills. As a result, the fish is infected with glochidia. (Oesch, 1984)

The middle lobe of the mantle edge has most of a bivalve's sensory organs. Paired statocysts, which are fluid filled chambers with a solid granule or pellet (a statolity) are in the mussel's foot. The statocysts help the mussel with georeception, or orientation.

Mussels are heterothermic, and therefore are sensitive and responsive to temperature.

Unionids in general may have some form of chemical reception to recognize fish hosts. Mantle flaps in the lampsilines are modified to attract potential fish hosts. Lampsilis fasciola has several different morphs of mantle flaps that resemble small fish. Whether the wavy-rayed lampmussel recognizes a particular fish host is unknown.

Glochidia respond to touch, light and some chemical cues. In general, when touched or a fluid is introduced, they will respond by clamping shut. (Arey, 1921; Brusca and Brusca, 2003; Watters, 1995)

In general, unionids are filter feeders. The mussels use cilia to pump water into the incurrent siphon where food is caught in a mucus lining in the demibranchs. Particles are sorted by the labial palps and then directed to the mouth. Mussels have been cultured on algae, but they may also ingest bacteria, protozoans and other organic particles.

The parasitic glochidial stage absorbs blood and nutrients from hosts after attachment. Mantle cells within the glochidia feed off of the host’s tissue through phagocytocis. (Meglitsch and Schram, 1991; Watters, 1995)

Unionids in general are preyed upon by muskrats, raccoons, minks, otters, and some birds. Juveniles are probably also fed upon by freshwater drum, sheepshead, lake sturgeon, spotted suckers, redhorses, and pumpkinseeds.

Unionid mortality and reproduction is affected by unionicolid mites and monogenic trematodes feeding on gill and mantle tissue. Parasitic chironomid larvae may destroy up to half the mussel gill. (Cummings and Mayer, 1992; Watters, 1995)

Fish hosts are determined by looking at both lab transformations and natural infestations. Looking at both is necessary, as lab transformations from glochidia to juvenile may occur, but the mussel may not actually infect a particular species in a natural situation. Natural infestations may also be found, but glochidia will attach to almost any fish, including those that are not suitable hosts. Lab transformations involve isolating one particular fish species and introducing glochidia either into the fish tank or directly inoculating the fish gills with glochidia. Tanks are monitored and if juveniles are later found the fish species is considered a suitable host.

In lab trials, Lampsilis fasciola has metamorphosed on the largemouth bass the smallmouth bass and the rock bass. (Cummings and Watters, 2004; Zale and Neves, 1982)

There are no significant negative impacts of mussels on humans.

Mussels are ecological indicators. Their presence in a water body usually indicates good water quality.

Lampsilis fasciola is listed as Endangered in Illinois, Threatened in Michigan and New York, and Special Concern in Indiana and North Carolina. In Canada, this species is federally Endangered under the Species At Risk Act. (Environment Canada, 2003; Hove, 2004)