Lampsilis cardium
plain pocketbook

The pocketbook is found in the Mississippi River drainage, St. Lawrence drainage and southern drainages to Hudson Bay. It occurs west from eastern Manitoba south to nothern Oklahoma, east to eastern Tennessee and north to Nova Scotia.

In Michigan the pocketbook is found throughout the lower peninsula, and in the upper peninsula, from Marquette and Dickinson County to the east. Collection records do not show it in Alger, Schoolcraft and Chippewa counties, although it still may be in water bodies there. (Oesch, 1984; Parmalee, 1967)

The pocketbook is found in lakes, streams and rivers, in mud, sand, and gravel. In the Huron River, they mainly occupied areas above and below riffles in sand or gravel. In the Huron’s lakes it was found mainly on solid shoals of sand, gravel or marl. (Cummings and Mayer, 1992; van der Schalie, 1938; Watters, 1995)

The pocketbook is up to 17.8 cm (7 inches) long , and is round or quadrate in shape. The shell is thinner in young individuals, thicker in older individuals, and inflated. This species is sexually dimorphic. The anterior end is rounded and the posterior end gently rounded in females and bluntly pointed in males. The dorsal margin is straight to gently curved and the ventral margin is broadly rounded.

Umbos are broad, elevated above the hinge line, and turned forward. The beak sculpture has four or five elevated ridges and may be double-looped.

The periostracum (outer shell layer) is smooth, yellow to yellow-green with green rays, although sometimes rays are absent.

On the inner shell, the left valve has two pseudocardinal teeth, which are erect, compressed, and striated. The posterior tooth is usually short and triangular. The two lateral teeth are short, thin and striated. The right valve has one erect and stout pseudocardinal tooth with another erect compressed tooth anteriorly. The one lateral tooth is high, thin and short.

The beak cavity is broad and deep. The nacre is white and iridescent posteriorly.

In Michigan, this species can be confused with the mucket, fat mucket, or wavy-rayed lampmussel. The mucket is more compressed. The fat mucket is more elongated. The wavy-rayed lampmussel in general has wavy rays, and because it is smaller than the pocketbook, the growth lines will be closer together. (Cummings and Mayer, 1992; Oesch, 1984; 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 cardium 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 cardium has a mantle flap resembling a minnow or darter to attrach host fish.

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. (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.

The main fish hosts for this species are probably centrarchids. Both natural infections and lab metamorphosis has been observed for the white crappie. In lab trials, Lampsilis cardium metamorphosed on bluegill, green sunfish, largemouth bass, and smallmouth bass. Lab transformations were also observed for the banded killifish and walleye. (Coker et al., 1921; Cummings and Watters, 2004; Lefevre and Curtis, 1912; Reuling, 1919; Waller et al., 1985; Watters, 1996)

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 cardium currently does not have any individual state conservation status. However, it is on the IUCN Red List as Lower Risk, Near Threatened.

Lampsilis cardium was formerly known as Lampsilis ventricosa and Lampsilis ovata ventricosa.