A medium-sized crayfish native to the Ohio River drainage. Now invasive in many other US waterways.

Also called: Crawfish, Crawdad, Mudbug

Native status: Native across eastern and central North America; multiple species

§ Quick facts

SizeBody 7–15 cm (3–6 in) excluding antennae
Weight30–200 g
LifespanWild 3–5 years; rarely 8
OrderDecapoda
FamilyCambaridae

§ Encyclopedia

The rusty crayfish is a large, aggressive species of freshwater crayfish which is native to the United States, in the Ohio River Basin in parts of Ohio, Kentucky, and Indiana. Its range is rapidly expanding across much of eastern North America, displacing native crayfishes in the process. The rusty crayfish was first captured in Illinois in 1973, and has been collected at over 20 locations in the northern portion of the state. In 2005, F. rusticus was found for the first time west of the Continental Divide, in the John Day River, Oregon, which runs into the Columbia River.

Source: Wikipedia — Rusty crayfish Licensed under CC BY-SA 4.0

§ Identification

Field marks. Medium-sized native crayfish with brownish-olive carapace, prominent rust-colored or dark side spots in some species, claws often colored at the joints.

Similar species. Other native crayfish genera (Procambarus, Cambarus). Invasive Rusty Crayfish has distinctive rust-colored side patches.

Voice. N/A

§ Diet & behavior

Diet. Omnivorous scavenger: aquatic plants, snails, small fish, insect larvae, fish eggs, dead matter.

Behavior. Genus Faxonius (formerly Orconectes) contains ~85 species and is the dominant crayfish genus across most of the central and eastern US. Many species look nearly identical and require examination of genital structures (gonopods) for accurate ID. Some species — especially the Rusty Crayfish (F. rusticus) — are aggressive invaders that displace natives where introduced through the bait trade.

§ Range

Native to Ohio Valley; invasive elsewhere

§ Habitat

Lakes, streams, rivers

§ Threats

In native range: pollution. In invaded range: they ARE the threat to native species.

§ Conservation status

According to the IUCN Red List, the crayfish (northern/eastern) is currently classified as Least Concern.

§ What helps

Don't move crayfish between waterways. Don't release bait crayfish.

Support our work More ways to help

§ Further reading

§ Sources cited

  • American Society of Mammalogists Faxonius Working Group
  • Crayfish Conservation Coalition
  • USGS Nonindigenous Aquatic Species