Mussels, Crayfish, & Moss Animals

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Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Order: Unionoida
Family: Unionidae
Genus: Elliptio
Species: Complanata
The species has an important role in filtering water and nutrients cycling and therefore water quality. Because of the species abundance and important role as both prey and water filtration, this species is among the more valuable benthic organisms to local ecosystems.New Hampshire Fish & Game

Found in the wet soil of Manchaug Pond is the Eastern Elliptio (Elliptio complanata complex), one of the most common freshwater mussel species in New England. Growing up to five inches in length and living for many years, the Eastern Elliptio begins it's life on the gills of certain host fish including brook trout, yellow and white perch, large and smallmouth bass, sunfish, black crappie, and pickerel and on those of American Toad (tadpole).

The outside of its shell is tan in juveniles to dark brown or black in adults. The inside of the shell, called the nacre, is colored white, pink, or purple. It’s iridescent surface, commonly called “mother-of-pearl, made it attractive and commonly used to make “pearl” buttons before the invention of plastic ones in the 1940’s. It doesn’t seem to have a preference for fast or slow flowing water or any particular substrate (soil). Freshwater mussels are filter feeders doing the important job of filtering nutrients and sediments from the water. When present in high numbers, the mussels help keep the water clear and of high quality with their presence considered an indicator of a healthy lake.

Dead, empty shells are often found along the shore or on docks as mussels are common food of muskrats and raccoons, but the biggest danger to these bivalved filter feeders is from chemical pollution and silt that can enter lakes and streams from the watershed which clogs the mussel’s gills. Also a factor, is the timing and speed of our drawdown of the water level in the fall which must allow the adult mussel to migrate, moving through the mud by burrowing with its muscular foot.

Known predators include: turtles, catfish, pumpkinseed, raccoons, mink, muskrats, and otters.  *


Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Crayfish break down plant materials, are an important food source for larger aquatic fauna, and can be an indicator of good water quality.Jennifer Moore Myers, USDA

Moss Animals or Bryozoans

Looking like small lobsters, these freshwater crustaceans are found near the shore living under submerged stones or walking along in shallow water.

Crayfish are a good indicator of water quality. Changes in pH and dissolved oxygen content are stressful to crayfish inhabiting freshwater ecosystems. High levels of dissolved oxygen may be stressful to crayfish because of physiological effects. A lower pH (more acidic conditions) could stunt growth of crayfish, with lasting effects even after the pH returns to normal levels. *

* DePauw University

Kingdom: Animalia
Class: Phylactolaemata
Order: Plumatellida
Family: Lophopodidae
Stem group: Pectinatella
Species: Magnifica
Bryozoans eat microscopic organisms and are eaten by several larger aquatic predators ... their presence usually indicates good water quality.Missouri Department of Conservation

Strange as it may seem, moss animals or bryozoans (Pectinatella magnifica) are aquatic organisms found at times in Manchaug Pond. They live in colonies forming a firm, gelatinous mass, typically less than a foot across, attaching themselves to submerged logs, twigs, stones and docks. Pectinatella magnifica, the magnificent bryozoan, is one of 19 species of freshwater bryozoans native to North America and found in calm and shady lakes and reservoirs.

Bryozoans are filter feeders that eat microscopic organisms, algae (phytoplankton) and organic matter from dead plants and animals (detritus) actually enhancing the water quality. In turn, they are eaten by several larger aquatic predators, including fish, snails and insects. Like mussels and other filter feeders, bryophytes gradually cleanse the water as they feed with their presence usually indicating good water quality.

Manchaug Pond Foundation Water Quality

Bryozoans live underwater attaching to rocks, docks and branches. Manchaug Pond 2008-09

Manchaug Pond Foundation Water Quality

A dead colony of bryozoans along the shore having washed downstream from Aldrich Mill Pond to Manchaug Pond.