Deliberate lateral and vertical movements by mussels does occur, but the movement is usually limited.  Because mussels don’t have vision, lateral movements can seem random and be multidirectional.  In some locations where ice can occur attached to the substrate (anchor ice), mussels may move vertically, burying into the substrate during the winter, and moving to the surface in the spring.  Vertical movements during the spring to early fall may also be related to reproduction or a response to disturbance by other animals, predators or people.  Lateral mussel displacement due to high flows or dislodgement due to predators or human activity also likely occurs.  Mussel larvae have a parasitic phase where they attach to a host fish and can be moved by that host within the aquatic system.

California floater adults grow up to five inches long and are elliptical, ovate or trapezoid-ovate in shape. The length to height ratio of this species is usually less than 1.5. The valves are thin and lightweight and may have a wing. The beak is small and rarely protrudes above the hinge line. The exterior color of the shell can be highly variable, from yellowish to brown or to black. The interior color of the shell is usually white but sometimes with a flesh-colored, purplish, or bluish tint. As “Anodonta” is Latin for “without teeth,” California floaters lack any sort of tooth within its valves.

The California floater and winged floater (Anodonta nuttalliana) can be considered to be in the same taxonomic clade.

Freshwater mussels are sedentary organisms, spending their entire lives near where they settled as juvenile mussels. They can use their foot to move laterally across sediments (usually short distances) or vertically within the sediments. Mussel movements may be related to reproduction or a response to physical disturbance and environmental changes such as water temperature, stream flows, or scouring of the stream bed. Mussel displacement due to high flows or dislodgement due to predators or human activity also likely occurs. The main mode of mussel dispersal comes through a stage of development when larvae (glochidia) parasitize a host fish and move with the host within the aquatic system.

California floaters are most often found in the sand and mud of lakes and reservoirs or in stable areas of low-gradient stream reaches. On rare occasions, individuals are found in streams with gravel bottoms.

Like all freshwater mussels, California floaters are filter feeders, siphoning suspended particles from the water column. They may consume plankton, bacteria, dissolved organic matter, or algae. This filtering provides an important water quality service by reducing turbidity and controlling nutrient levels, especially where there are dense mussel beds. Particles not used by the mussel are often re-formed and expelled as larger particles that are in turn used as food by other aquatic life.

Anodonta species become sexually mature at about four to five years old and can live up to about 15 years. Relative to other western mussel species, they are considered short lived and fast growing. Males release sperm into the water column and a female takes them in through her incurrent siphon to fertilize eggs. Fertilized eggs migrate within the mussel to a special portion of the gill known as the marsupium. The eggs develop into larvae called glochidia and are released by the female in the spring through early summer. Once released the glochidia, which look like very tiny mussels, attach to a host fish’s gills where they become encysted and remain for weeks to months until they detach and settle to the substrate. Mussel species are often specific regarding what species of fish they use as hosts. Known host fish of the California floater include pit sculpin (Cottus pitensis), Sacramento pikeminnow (Ptychocheilus grandis), tule perch (Hysterocarpus traski), and green sunfish (Lepomis cyanellus). Anodonta glochidia in the west have been found on fish from the fall through the spring. Timing of reproductive events is affected by habitat, water temperature and the individual species.