Big Water Crayfish, Cambarus robustus

OTHER COMMON NAMES

Robust crayfish

ETYMOLOGY

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.

QUICK FACTS

Avg carapace length: <2.25 inchesLife expectancy: 3-4 yearsAge at maturity: 3rd summerHabitat: 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 macroinvertebratesNative or non-native: Non-nativeActivity pattern:

Nocturnal

Uses: Possibly as bait

Life History Event Date/Season
Mating
Fertilization
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
ROSTRUM

Broadly tapering, with rounded corners leading to pointed acumen.

COLOR/MARKINGS

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

CHELAE

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.

AREOLA

Open, wide areola.

Range map for Big Water Crayfish

Range map based on observations from iNaturalist.org

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

Crayfish of Vermont species profiles