Common name: Kentucky River crayfish
Synonyms and Other Names: Orconectes juvenilis (Hagen, 1870). Faxonius juvenilis underwent a reclassification in August 2017, changing the genus of non-cave dwelling Orconectes to Faxonius (Crandall and De Grave 2017).
Identification: Orconectes juvenilis is 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 black bands. The rostrum is characterized as moderately excavated without median carina with margins slightly curved and converging, and terminating in spines. Edges of abdominal segments, articulation joints, and lateral edge of chela are red or orange. Ventral surfaces are a cream to white color. Form I males have two long thin elements on gonopod (Taylor 2000; Taylor et al. 2015).
O. juvenilis and O. rusticus are morphologically similar with both having blade-like mandibles, which separates them from the rest of the “juvenilis complex” that have serrated mandibles. O. juvenilis differs from O. rusticus in length of the first gonopod and the ratio of the central projection to gonopod length (Taylor 2000; Amandus 2014).
Size: Maximum size 81.5 mm in total length (Taylor and Schuster 2004).
Native Range: Range as determined by Taylor (2000) is now restricted to a narrow stretch of the Ohio River drainage of northcentral Kentucky and southeastern Indiana. Orconectes juvenilis can be found in portions of the Kentucky River drainage, upper Cumberland (above the falls), the Rockcastle, and the Salt River drainages in Kentucky.
Hydrologic Unit Codes (HUCs) Explained
Puerto Rico &
Interactive maps: Point Distribution Maps
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 juvenilis are found here.
Table last updated 2/27/2023
† Populations may not be currently present.
Ecology: Orconectes juvenilis is a habitat generalist which inhabits small streams to rivers with mud, gravel, cobble, boulder, or fractured bedrock substrates. The species can be found commonly under large rocks and occasionally in wood debris or undercut banks (Taylor 2000; Taylor and Schuster 2004; Taylor et al. 2015)
Means of Introduction: This species has been introduced by deliberate stocking (Chucholl 2013) and through bait buckets releases.
Impact of Introduction: Orconectes juvenilis is a snail predator (Dickey and McCarthy 2007), and could have negative influences on native snail populations. This species can be a vector of the crayfish plague (caused by the fungus Aphanomyces astaci) and spread it among native crayfish populations (Holdich et al. 2009).
References: (click for full references)
Amandus, R. 2014. Molecular and Morphological Evidence for Multiple Cryptic Crayfish Invasions in the Southern Appalachian Mountains (Doctoral dissertation, Appalachian State University).
Chucholl, C. 2013. Invaders for sale: trade and determinants of introduction of ornamental freshwater crayfish. Biological Invasions. 15(1): 125-141.
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.
Dickey, B. F., and T.M. McCarthy. 2007. Predator–prey interactions between crayfish (Orconectes juvenilis) and snails (Physa gyrina) are affected by spatial scale and chemical cues. Invertebrate Biology. 126(1): 57-66.
Holdich, D. M., Reynolds, J. D., Souty-Grosset, C., and P.J. Sibley. 2009. A review of the ever increasing threat to European crayfish from non-indigenous crayfish species. Knowledge and Management of Aquatic Ecosystems. 11
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 G.A. Schuster. 2004. The crayfishes of Kentucky. Illinois Natural History Survey Special Publication. No.28. vii+219 pp.
Revision Date: 6/14/2017
Daniel, W.M., 2023, Faxonius juvenilis (Hagen, 1870): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=2904, Revision Date: 6/14/2017, Access Date: 3/31/2023
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.