Northern Clearwater Crayfish, Faxonius propinquus

OTHER COMMON NAMES

None

ETYMOLOGY

Faxonius, named for Walter Faxon (1848-1920), American ornithologist and carcinologist. Former genus, Orconectes, is from Orcus, god of the underworld in Roman mythology + nectes: swimming (Greek); propinquus: nearby (unclear what this is in relation to)

Ecology, Habitat, & Behavior

It’s hard to say much about about the northern clearwater crayfish with any specificity, as they’re generalists in terms of both habitat and diet. They’ve a slight preference towards streams with medium flow where the river is free of vegetation and the river bottom is more rocky than muddy. Typically these environments have low sediment load. While other species are capable of avoiding desiccation by burrowing, northern clearwater crayfish do not burrow. As such, they’re confined to permanent bodies of water (e.g. lakes, ponds, wide rivers, quick flowing brooks).

They’re active both at night and during the day. One study found that they’re least active at night near a full moon, and most active near a new moon (source). When they do emerge from refugia (under rocks or logs), they forage on a broad range of foods, trending slightly towards plant material (though they opportunistically will consume large amounts of trout, bluegill, and other fish eggs).

QUICK FACTS

Avg carapace length: 1-1.5 inchesLife expectancy: 3-4 yearsAge at maturity: 2nd year (some males in 1st summer)Habitat: Generalist# of eggs: 75-100 (source)Diet: Generalist omnivoreNative or non-native: Native Activity pattern:

Diurnal

Uses: Bait, aquarium pets

Life History Event Date/Season
Mating Autumn or early spring
Fertilization Spring
Females laying eggs Late May – early June
Hatch in 3-6 weeks
Larvae leave mother After 3 molts
Males in F1  Late summer
Males in F2 Spring

Key features for ID + similar species

Extremely similar to the much less common Allegheny crayfish, which lakes the medial carina

  1. Concave rostrum with a carina (keel) in the middle
  2. Dark brown wedge on abdomen
ROSTRUM

Straight, tapering margins with side projections and a sharply pointed acumen. Rostrum is concave and with a carina (keel), which is sometimes difficult to see and other times obvious.

COLOR/MARKINGS

A dark wedge-shaped band (or saddle) down the top side of the abdomen. Color can be variable, but somewhat brownish green.

CHELAE

S-shaped dactyl. Generally free of tubercles. Tips of fingers are orange to red with subterminal black rings (though these aren’t always present and are not as prominent as with the rusty crayfish when they are).

AREOLA

Wide areola (the gap between the carapace plates).

Range map for Northern Clearwater 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 obscurus, O. sanborni, and O. propinquus: source
  • 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