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. How the eastern pondmussel attracts and/or recognizes its 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.
Communication Channels: chemical
Perception Channels: visual ; tactile ; vibrations ; chemical
Ligumia nasuta is listed as Endangered in Delaware and Ohio, Threatened in New Jersey and Special Concern in Massachusetts. It is also a Species of Concern in Rhode Island. The IUCN Red List considers this species Lower Risk, near Threatened on the IUCN Red List.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: lower risk - near threatened
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.
Development - Life Cycle: metamorphosis
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.
While freshwater mussels require a host fish for metamorphosis, the host for the eastern pondmussel is unknown.
Ecosystem Impact: parasite
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.
Plant Foods: algae; phytoplankton
Other Foods: detritus ; microbes
Foraging Behavior: filter-feeding
Primary Diet: planktivore ; detritivore
The eastern pond mussel is found from the James River of Virginia north to the St. Lawrence drainages in Canada, west to Lake Erie, Ohio and Michigan.
In Michigan L. nasuta is found in the lower peninsula in drainages on the eastern side of the state. Generally, this is a pond and lake species.
Biogeographic Regions: nearctic (Native )
The eastern pondmussel is usually found in lakes, ponds, or quiet waters of streams. Substrates it inhabits are variable. In the Huron River this species was found on sandy bottoms of quiet pools or in sandy areas of beach pools.
Habitat Regions: freshwater
Aquatic Biomes: rivers and streams
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.
The eastern pondmussel is up to 10 cm (4 inches) long , and is elongate in shape, usually over twice as long as high. The shell is usually fairly thin and compressed, and this species has a distinct posterior ridge. The anterior end is rounded, the posterior end pointed. The dorsal margin is straight and the ventral margin is straight to curved as it .
Umbos are low, being raised only slightly above the hinge line. The beak sculpture has double-looped ridges.
The periostracum (outer shell layer) is smooth, except for growth lines and tan to dark green, sometimes with fine green rays. Older specimens tend to be more brown or black.
On the inner shell, the left valve has one to two pseudocardinal teeth, which are triangular and delicate. The two lateral teeth are straight and long. The right valve has one triangular pseudocardinal tooth The one lateral is also straight and long.
The beak cavity is shallow to moderately deep. Although the nacre is white, occasionally it is has a pink or salmon tint and is iridescent at the posterior end.
In Michigan, this species can be confused with the black sandshell. The black sandshell is more cylindrical, not as pointed posteriorly, and is generally larger and thicker.
Range length: 10 (high) cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes shaped differently
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.
Known Predators:
Age to sexual maturity for this species is unknown. Unionids are gonochoristic (sexes are separate) and viviparous. The glochidia, which are the larval stage of the mussels, are released live from the female after they are fully developed.
In general, gametogenesis in unionids is initiated by increasing water temperatures. The general life cycle of a unionid, includes open fertilization. Males release sperm into the water, which is taken in by the females through their respiratory current. The eggs are internally fertilized in the suprabranchial chambers, then pass into water tubes of the gills, where they develop into glochidia.
Ligumia nasuta is a long-term brooder. In the Huron River in Michigan, it was gravid from early August to late June. It probably spawns in July in Michigan.
Breeding interval: The eastern pondmussel breeds once in the warmer months of the year.
Breeding season: In Michigan, the breeding season is probably July.
Range gestation period: 11 (high) months.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous
Females brood fertilized eggs in their marsupial pouch. The fertilized eggs develop into glochidia. There is no parental investment after the female releases the glochidia.
Parental Investment: pre-fertilization (Provisioning); pre-hatching/birth (Provisioning: Female)
