Anódon

Anódon, typically written Anodonta in taxonomic usage, is a genus of freshwater mussels in the family Unionidae. The name derives from Greek roots meaning “without tooth,” a reference to the relatively simple hinge structure found in many species. The genus comprises several species distributed across the Northern Hemisphere, especially Europe and North America.

These bivalves have relatively thick shells that are often rounded to elongated and may be brown, olive, or yellowish in color. The inner shell surface is usually nacreous and pale. In general, Anodonta species are large to medium-sized mussels with a smooth to slightly ribbed exterior. The hinge teeth are typically reduced or few, contributing to a perception of a toothless hinge in some species.

Anódon mussels are filter feeders that inhabit freshwater bodies such as rivers, streams, lakes, and ponds with soft to moderately firm substrates. They play a role in water filtration and ecosystem functioning. Reproduction involves separate sexes; fertilization occurs in the water, and the developing larvae (glochidia) temporarily parasitize fish hosts before dropping to the substrate as juvenile mussels. This obligate host relationship makes their life cycles sensitive to changes in fish populations and water quality.

Conservation status varies by species and region. Many Anodonta populations have declined due to habitat destruction, sedimentation, pollution, damming, and competition or predation by invasive species. Several species are considered threatened or of concern in various national and regional assessments. Taxonomic treatment has shifted over time, with some authorities relocating certain species to other genera, reflecting ongoing revisions in Unionidae systematics.