Swan Mussel Shell

Anodonta cygnea

Low water levels leave Swan Mussels exposed and vulnerable to predators. They are freshwater bivalve molluscs that typically grow between 12 and 20 cm long. A mussel uses its muscular foot to partially bury itself in soft sediment. They are filter feeders that draw in water to remove microscopic algae, bacteria, and organic particles, which helps to purify the water. The thin, elongated shell can be yellowish-brown, pale green, or brown, with an inner layer of iridescent nacre known as mother-of-pearl. Females brood their eggs in specialised gill chambers. Males release sperm into the water, which females draw in through their inhalant siphon to fertilise the eggs. During spring, the larvae called glochidia hatch and are released into the water. The larvae cannot swim independently and must attach to host fish to survive. Once attached, a larva forms a protective cyst and feeds on the host's body mucus. The young mussel spends several weeks on the host before detaching itself and settling on the lakebed to begin a life of independence.

Swan mussels filter the water, trapping metals, bacteria, and toxins. They taste unpleasant and eating them can lead to severe food poisoning, stomach illness, or infections like E. coli.