Connecticut Department of Energy & Environmental Protection

Emergency Burn Ban In Effect 10/26/24 - An emergency burn ban is now in effect for all Connecticut State Parks, Forests, and Wildlife Management areas, prohibiting the use of all outdoor grills, firepits, and campfires, and the kindling and use of flame outdoors. DEEP and local agencies are working to contain several active fires across the state. Please avoid all affected State Parks and Forests, as well as the blue-blazed Mattabesett Trail. The Enduro Trail in Voluntown and portions of North Stonington within the Pachaug State Forest are closed at this time. Please note that today's forest fire danger report remains at an 'extreme' level. More information about the current fire danger, burn ban and recommended safety measures can be found here

Triangle Floater

Alasmidonta undulata

Key Features

Size: Up to three inches.

Shape: Subovate. Ventral margin rounded. Its laterally inflated valves and subovate shape give it a “plump” appearance. Beaks prominent.

Periostracum: Color yellowish-green (juveniles) to greenish-brown (adults) or black. Shell rays numerous.
Lateral Teeth: Absent.

Pseudocardinal Teeth: Present and well developed. The stout teeth are buttressed by a heavy ridge.
Nacre: Usually distinctly bicolored. Posterior half thin and an iridescent bluish-pink, and the anterior half thick and usually whitish-pink.

Often Confused With ... Dwarf wedgemussel, brook floater, creeper

External shell of the Triangle Floater

External shell

Internal shell, right valve of Triangle Floater

Internal shell, right valve

Hinge teeth of Triangle Floater

Hinge teeth

Habitat: The triangle floater is found in streams, rivers, and lakes, where it seems to prefer sand and gravel substrates. It is the only Alasmidonta species in Connecticut that can be found in lakes, though it is more commonly found in small to medium-sized rivers.

Range in Connecticut: The triangle floater exists in most watersheds in Connecticut, though it is particularly common in the Connecticut River watershed.

Conservation: The triangle floater is widespread in Connecticut and there are many large healthy populations. It seems to be less sensitive to pollution and habitat disturbance—and uses a broader range of host fish—than its close relatives, the brook floater and dwarf wedgemussel. It is an important indicator of river health, and may be declining in southern parts of its range, such as Maryland where it is listed as endangered. It is listed as special concern in Massachusetts and Maine.

Freshwater Mussel Fact Sheets

Eastern Pearlshell
Dwarf Wedgemussel
Triangle Floater
Brook Floater
Creeper
Eastern Elliptio
Eastern Floater
Alewife Floater
Eastern Pondmussel
Tidewater Mucket
Yellow Lampmussel
Eastern Lampmussel

The Freshwater Mussels of Connecticut

Content last updated on January 29, 2014.