Big Water Crayfish, Cambarus robustus


Robust crayfish


Cambarus from kammaros: lobster (Greek) + robustus: robust, large (in reference to the robust chelae)

Ecology, Habitat, & Behavior

Big water crayfish, like many other crayfish with discrete and isolated populations represent a species complex (source). The group is often treated as separate species, with much of their diversity coming from the established patchy and isolated populations down in the Appalachians. Some of these populations are stable, while others are threatened by habitat loss (source).

They are usually found in faster flowing rivers with rocky substrates, though they can also be found in rocky sections of ponds and lakes. Big water crayfish have a higher tolerance for pollution, sediment load, and acidity than most crayfish. As a result, their range has steadily expanded in the recent past.

Our two Cambarus species are both far less synchronous in their molting and life stages than Faxonius species.

  • Avg carapace length: <2.25 inches
  • Life expectancy: 3-4 years
  • Age at maturity: 3rd summer
  • Habitat: Generalist, but typically faster flowing river environments
  • # of eggs: 5-200 (source)
  • Diet: Juveniles are filter feeders, adults feed on plant material, smaller crustaceans, and macroinvertebrates
  • Native or non-native: Non-native
  • Activity pattern:


  • Uses: Possibly as bait
Life History Event Date/Season
Laying Eggs
Young detach from female

Key features for ID + similar species

  1. Concave on outer margin of palms
  2. Two rows of tubercles on mesial margin of chelae

Broadly tapering, with rounded corners leading to pointed acumen.


Body is greenish-brown, but otherwise lacking distinguishing color patterns.


Large relative to body size, wide, with two rows of tubercles on the mesial margin of the chelae. The palm has a slight depression on the outer margin. Dactyls are straight, hooked at tip.


Open, wide areola.

General Research on Crayfish

  • NOBANIS: Invasive Alien Species Fact Sheet : source
  • Crayfish of the White River Watershed: source
  • Crayfish curriculum for educators: source
  • The Crayfishes of New England: source
  • Species of Ontario Crayfish: source
  • Lecture on Crayfish: video
  • Some aspects of the life histories of three closely related crayfish species, Orconectes obscurusO. sanborni, and O. propinquussource
  • Dictionary of crayfish names: source
  • Biological synopsis of the rusty crayfish: source
  • Observations on the life cycle of Procambarus acutus acutus in South Carolina culture ponds: source
  • Natural History of the two Crayfish of Northwestern Iowa, Orconectes virilis and Orconectes immunis: source