Like other freshwater mussels, the fat pocketbook is a filter feeder, filtering out food particles (3) as water is continuously pumped through specialised siphons (4) (9). During this process, the adult mussel removes unwanted toxins from the water and gathers necessary nutrients (9) from items such as plankton and detritus (3) (4). Fat pocketbook larvae feed on the bodily fluids of fish (3).
The fat pocketbook has been reported to require a stable, undisturbed habitat with a sufficient population of suitable fish hosts to complete its life cycle (8). To reproduce, the male discharges sperm into the water current and the female positions itself downstream. The female then uses its siphons to intake the sperm and fertilise its eggs (3) (8). Spawning in the fat pocketbook occurs from late August through September (9).
Fertilised eggs are stored in the gill pouches of the female until the larvae (3), known as ‘glochidia’, are fully developed, at which point the glochidia are expelled by the female (8). In the fat pocketbook, glochidia release typically takes place in June and July (9). Once released into the water, the glochidia must find a suitable host fish within a couple of days to enable them to develop into adult mussels (3). Tiny, clasping valves are used to clamp onto the fins or gills of a host fish (8) (9), which in the fat pocketbook is the freshwater drum (Aplodinotus grunniens) (3) (9) (10). After a period of between two and four weeks (9), the juvenile mussels detach from the host fish and settle into the streambed to grow and reproduce (8) (9).