Astacus astacus

Noble crayfish can vary greatly in colour.[3]

European crayfish feed on worms, aquatic insects, molluscs, and plants.

They are nocturnal, spending the day resting in a burrow.

A. astacus become sexually mature after three to four years and a series of moults, and breed in October and November. Fertilised eggs are carried by the female, attached to her pleopods, until the following May, when they hatch and disperse.

The main predators of A. astacus, both as juveniles and adults, are mink, eels, perch, pike, otters, and muskrats.[2]

This species was once abundant in Europe, although it was expensive to buy, and is considered to be the finest edible crayfish.[2] It is, however, susceptible to the crayfish plague carried by the invasive North American species signal crayfish (Pacifastacus leniusculus), so is listed as a vulnerable species on the IUCN Red List.[1]

Documentation of the consumption of A. astacus dates back to the Middle Ages, when it was popular among the Swedish nobility, spreading to all social classes by the 17th and 18th centuries due to its ready availability. The crayfish are collected from the wild in traps, a practice which is being replaced by more intensive aquaculture of the signal crayfish in man-made ponds.[4] The consumption of crayfish is an important part of traditional Nordic culture, including the crayfish party (Swedish: kräftskiva; Finnish: rapujuhlat), a feast to mark the end of summer.[4]

Hundreds of smaller or larger lakes were once found in the northern Moldavia, used for growing A. astacus meant for consumption during the extended fasting periods of the Orthodox Christian calendar. The area of the former Dorohoi County was one such area, and this legacy was visible in the county's historical coat of arms, featuring an A. astacus (Rmn. rac).

Astacins are a family of digestive enzymes, discovered in the 1990s, which were first isolated from A. astacus. More than 20 enzymes of this group have since been discovered in animals from Hydra to humans.[5]