Identification: This species is described by Taylor (2000) as being a brown to tan to olive green color with dorsal surfaces of chelae covered with small dark flecks. The fingers of chelae are tipped in orange and followed proximally by thin black bands. Sometimes the first abdominal segment has a dark brown U-shaped saddle centered at the caudal margin. The rostrum is characterized as flat with margins thickened, terminating in upturned corneous spine. Edges of abdominal segments, articulation joints, and lateral edge of chela are red or orange. Ventral surfaces are a cream to white color.
Orconectes cristavarius differs from all other members of the genus Orconectes by possessing a unique combination of chelae, serrated mandibles, and antennal scale characters (see Taylor 2000).
Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Faxonius cristavarius are found here.
Table last updated 12/4/2023
† Populations may not be currently present.
Ecology: Orconectes cristavarius occurs in creeks and small to medium-sized rivers with moderate-to low- velocity and substrates of cobble and gravel (Taylor 2000; Loughman et al. 2009). Adults were usually found under large slab rocks or cobble in various parts of the stream: midstream and along the stream margin (Simmons and Fraley 2010); shallow riffles or runs (Taylor 2000); or detritus beds in pool thalwegs (Loughman et al. 2009). In West Virginia, large numbers of adults were seen in backwater pools during late summer (Loughman et al. 2009). Juveniles were often collected from beneath undercut banks or shallow pools (Loughman et al. 2009; Simmons and Fraley 2010).
Fortino and Creed (2007) demonstrated that O. cristavarius was the dominate crayfish species in the downstream reaches of the South Fork of the New River, NC. It was hypothesized that differences in escape behavior from rock bass (Ambloplites rupestris) and growth rate may have contributed to the differences in distribution between Cambarus chasmodactylus as the dominant species in third-order tributaries and O. cristavarius as the dominant species in the mainstem fourth-order South Fork.
References: (click for full references)
Cooper, J.E. 2005. Crayfishes occurring in North Carolina. North Carolina State Museum of Natural Sciences, Raleigh, NC
Crandall, K.A. and S. De Grave. 2017. An updated classification of the freshwater crayfishes (Decapoda: Astacidea) of the world, with a complete species list. Journal of Crustacean Biology 37(5):615-653. https://doi.org/10.1093/jcbiol/rux070.
Fortino, K., & Creed, R. P. 2007. Abiotic factors, competition or predation: what determines the distribution of young crayfish in a watershed?. Hydrobiologia. 575(1): 301-314.
Hill, A.M., D.M., Sinars, and Lodge, D.M. 1993. Invasion of an occupied niche by the crayfish Or- conectes rusticus: potential importance of growth and mortality. Oecologia. 94:303-306
LeGrand, H.E., Jr., S.P. Hall, S.E. McRae, and J.T. Finnegan. 2006. Natural Heritage Program List of the Rare Animal Species of North Carolina. North Carolina Natural Heritage Program, Raleigh, North Carolina. 104 pp.
Loughman, Z.J., Simon, T.P., and Welsh, S.A. 2009. West Virginia crayfishes (Decapoda: Cambaridae): observations on distribution, natural history, and conservation. Northeastern Naturalist. 16(2): 225-238.
Loughman, Z. J., & Welsh, S. A. 2010. Distribution and conservation standing of West Virginia crayfishes.
McGrath, C. 1998. New River basin aquatic inventory. North Carolina Wildlife Resources Commission, Nongame Project Report, Raleigh, NC
Pintor, L. M., and Sih, A. 2009. Differences in growth and foraging behavior of native and introduced populations of an invasive crayfish. Biological Invasions. 11(8): 1895-1902.
Simmons, J.W., & Fraley, S.J. 2010. Distribution, status, and life-history observations of crayfishes in western North Carolina.
Taylor, C.A. 2000. Systematic studies of the Orconectes juvenilis complex (Decapoda: Cambaridae), with descriptions of two new species. Journal of Crustacean Biology. 20(1): 132-152.
Taylor, C. A., and Schuster, G. A. 2004. The crayfishes of Kentucky. Illinois Natural History Survey Special Publication. No.28. vii+219 pp.
Thoma, R.F. and R.E. Jezerinac. 2000. Ohio crayfish and shrimp atlas. Ohio Biological Survey Miscellaneous Contribution 7: 1-28
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.