Spiny-cheek crayfish
Faxonius limosus
The spiny-cheek crayfish is a medium-sized freshwater decapod native to eastern North America. It is characterized by small spines on the sides of its carapace and dark reddish-brown bands across the abdominal segments. In Europe, it is considered a highly invasive species, acting as a primary carrier of the crayfish plague and outcompeting native species due to its high tolerance for pollution and rapid reproduction.
Details
Identification
Spines on the cheeks in front of the cervical groove, reddish-brown transverse bands on the abdominal segments, inner sides of claws often orange with black tips.
Social behavior
Solitary and territorial, but shows lower levels of aggression at high population densities compared to native species.
Diet
Opportunistic omnivore: feeds on aquatic plants, detritus, insect larvae, snails, mussels, and small fish.
Hunting strategy
Combination of active scavenging, filtering detritus, and ambush hunting of small invertebrates.
Spawning substrate
Eggs are attached by the female to the pleopods under the abdomen.
Overwintering
Overwinters in deeper, frost-free water zones or in self-excavated burrows in the banks.
Ecology
Ecological role
Important decomposer and predator; acts as a vector for the oomycete Aphanomyces astaci (crayfish plague).
Natural predators
Predatory fish such as eel, perch, and catfish, as well as herons, otters, and muskrats.
Competitor species
Noble crayfish (Astacus astacus), stone crayfish (Austropotamobius torrentium), signal crayfish (Pacifastacus leniusculus).
Ecosystem service
Removal of carrion and organic matter; serves as prey for various predators.
Threats
Hardly threatened in Europe; local population declines possible due to extreme pollution or overpopulation.
Scientific profile
Profile
Distinguishing features
The definitive feature is the dark reddish-brown transverse bands on the dorsal side of the abdominal segments. Additionally, the species possesses two pairs of postorbital ridges and distinct lateral spines on the rostrum. The underside of the claws is light beige to whitish without red joint membranes.
Diet
Detritus, leaf litter, aquatic plants, algae, as well as animal matter such as insect larvae, snails, mussels, fish eggs, and small fish.
Reproduction
Sexual reproduction; mating occurs in autumn or spring. Females carry the eggs (approx. 100-500) under the abdomen over winter or in spring. Rapid development and early sexual maturity often reached after just one year.
Role in food web
Important consumer of organic matter; serves as prey for predatory fish (eel, perch) and birds. As an invasive alien species, it displaces native species through competition and as a vector for the crayfish plague.
Protection & threats
Main threats
No significant threats in Europe; in its native range (North America), locally affected by habitat loss and water pollution.
Conservation measures
No conservation measures; management aims at preventing dispersal (e.g., crayfish barriers, bans on moving live specimens, angler education).