Astacus

Astacus is a genus of freshwater crayfish in the family Astacidae, native to Europe and parts of Asia. As decapod crustaceans, they inhabit streams, rivers, and lakes and are among the organisms commonly referred to as crayfish or crawfish.

The genus includes several species, most notably Astacus astacus, the European crayfish, and Astacus leptodactylus, the Turkish crayfish. Taxonomic revisions in recent decades have moved some former Astacus species into other genera such as Pontastacus.

They have a broad carapace, a rostrum with marginal teeth, five pairs of legs with large claws, and a segmented abdomen ending in a tail fan.

They prefer cool, well-oxygenated freshwater and are typically found in streams and lakes with substrates of sand, gravel, or leaf litter. They are omnivorous scavengers, feeding on plants, algae, invertebrates, and detritus. Reproduction occurs in spring, with females carrying eggs under the abdomen until hatching; juveniles resemble adults and reach maturity after several years depending on conditions.

Conservation and human use: In Europe, native Astacus astacus has declined due to habitat loss, pollution, and the crayfish plague, caused by the oomycete Aphanomyces astaci, transmitted by introduced non-native crayfish. Invasive species, disease, and climate change threaten remaining populations. Some Astacus species are fished commercially or raised in aquaculture, and management often emphasizes disease-free stock and habitat protection.