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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: Everglades Crayfish

Synonyms and Other Names: Electric Blue Crayfish

Taxonomy: available through www.itis.gov

Identification: The Everglades Crayfish, Procambarus alleni, is widely available in the aquarium trade due to the brilliant blue color morphs that are bred in captivity (Inman 1998; Chucholl and Wendler 2017). Wild caught specimens can be blue, brown, or red in color. This species has a rostrum with or without lateral spines, relatively narrow areola that is 7 to 14 times as long as it is wide, postorbital ridges terminating cephalad with or without spines, and one lateral spine usually present on sides of carapace (Hobbs 1942). Procambarus alleni can be distinguished from P. fallax (Slough Crayfish) through the presence of dark, circular areas, referred to as “headlights”, found at the base of both antennal glands (Hendrix and Loftus 2000; Vanarman 2003). Due to variation in the morphology of both species, identification between P. alleni should be verified by microscopic examination of the secondary sexual features illustrated in Hobbs (1989) and Vanarman (2003). A mature male (Form I) P. alleni can be recognized through the presence of hooks on the third and fourth pereiopods. Additionally, knobs used to hold females in place during mating can be seen at the base of the fifth pereiopod of form I males (Hobbs 1989; Vanarman 2003).

Size: Adults have a maximum carapace length (CL) of 39.8-44.3 millimeters (mm) (Dorn and Trexler 2007; Vanarman 2003).

Native Range: The native range of P. alleni encompasses the majority of central and southern Florida (Hobbs 1942). The northern extent of P. alleni’s distribution extends along the St. Johns River from its mouth, south to northern Seminole County, westward to Bushnell in Sumter County, and then northwest through Citrus and southern Levy County to the mouth of the Suwannee River (Hobbs 1942). The southern edge of the native range encompasses the Everglades, and a few of the Florida Keys (Hobbs 1942; Hobbs 1984).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Procambarus alleni inhabit a wide range of ephemeral and permanent wetlands, including prairie marshes, flood plains, road side ditches, and small streams (Hobbs 1942; Hendrix et al. 1998). Although P. alleni have been collected from flowing waters, their habitat preference appears to be temporary, freshwater bodies of water that are still or very sluggish, or littoral zones that periodically desiccate due to seasonal droughts (Hobbs 1942; Hendrix et al. 1998; Dorn and Volin 2009).  This crayfish typically occupies freshwater systems, but they have been collected from waterways with salinities as high as 18 parts per thousand (ppt) (Hendrix et al. 1998). During the rainy season (summer and fall), P. alleni inhabit inundated shorelines, where dense vegetation limits predation by fishes and conspecifics (Jordan et al. 1996; Hendrix et al. 1998). Procambarus alleni commonly co-occur with Procambarus fallax during periods of inundation; however, during droughts the two species are partitioned based on hydrologic conditions. During the dry season (winter and spring), while P. fallax continues to occupy areas that remain flooded, P. alleni seeks refuge in burrows (Hobbs 1942; Hendrix et al. 1998).

Procambarus alleni constructs and utilizes burrows during droughts and reproductive periods (Hobbs 1942; Hendrix et al. 1998). The entrance of P. alleni burrows can often be identified through conspicuous mounds or chimneys constructed from excavated materials (Hendrix et al. 1998). P. alleni is capable of burrowing effectively in peat, marl, and sand substrates, but its resilience to desiccation varies depending on the substrate composition (Dorn and Volin 2009). P. alleni may remain in their burrows for months to avoid desiccation and to reproduce (Hobbs 1942; Hendrix et al. 1998).

The life cycle of P. alleni follows that of most Procambarids (Hobbs, 1942; Hendrix et al. 1998). Like P. clarkii, P. alleni mature at approximately one year of age. The mean size of reproductively active males was reported as 29.3 mm in CL, but this varied from 19.2-38.9 mm CL. The mean size at maturity for females excavated in the same study was estimated to be 27.9 mm CL, varying from 18.2 to 34.4 mm CL. Oviposition occurs while individuals are burrowed during the dry season (Hendrix et al. 1998). The young hatch within the burrow, and like other procambarids, P. alleni undergo a period in which newly hatched young stay attached to the female's pleopods. Reflooding of the littoral zone brings crayfish to the surface with the young still attached. While the duration of attachment varies, the hatched young appear to recruit to the population by the following summer (Hendrix et al. 1998).

Means of Introduction: Means of introduction is unknown, but introductions via an aquarium releases are probable due to its popularity in the pet trade. Another possible vector of introduction is through the bait industry (Inman 1998).

Status: Unknown

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

Remarks: Consumers dependent on P. alleni for a substantial portion of their diet include Largemouth Bass (Micropterus salmoides), Warmouth (Lepomis gulosus), Eastern Glossy Ibis (Plegadis flacinellus), American Bittern (Botaurus entiginosus), White Ibis (Eudocimus alba), Pied Billed Grebe (Podilymbus podiceps) and Little Blue Heron (Egretta caerulea) (Gunderson and Loftus 1993).

A single P. alleni was collected from the Rhein River in Germany. This specimen was likely an aquarium release due to its prevalence in the European aquarium trade. (Kouba et al. 2014; Mrugala et al. 2015).

References: (click for full references)

Chucholl, C., and F. Wendler. 2017. Positive selection of beautiful invaders: long-term persistence and bio-invasion risk of freshwater crayfish in the pet trade. Biological Invasions 19(1):197-208.

Dorn, N.J., and J.C. Trexler. 2007. Crayfish assemblage shifts in a large drought-prone wetland: the roles of hydrology and competition. Freshwater Biology 52(12):2399-2411.

Dorn, N.J., and J.C. Volin. 2009. Resistance of crayfish (Procambarus spp.) populations to wetland drying depends on species and substrate. Journal of the North American Benthological Society 28(4):766-777. https://www.jstor.org/stable/10.1899/08-151.1

Gunderson, L.H., and W.F. Loftus. 1993. The Everglades in Martin, W.E., S.G. Boyce, A.C. Echternacht, ed. Biodiversity of the southeastern United States: lowland terrestrial communities. 1 edition. Wiley. Hoboken, New Jersey.

Hendrix, A.N., D. Armstrong, and C. Grace. 1998. Life history, ecology, and interactions of Everglades crayfishes. National Park Service, Homestead, FL.

Hendrix, A.N., and W.F. Loftus. 2000. Distribution and relative abundance of the crayfishes Procambarus alleni (Faxon) and P. fallax (Hagen) in southern Florida. Wetlands 20:194-199. https://pubs.er.usgs.gov/publication/70022895

Hobbs, H.H. Jr. 1942. The crayfishes of Florida. University of Florida, Gainesville, FL.

Hobbs, H.H., Jr. 1984. On the distribution of the crayfish genus Procambarus (Decapoda: Cambaridae). Journal of Crustacean Biology 4(1):12-24.

Hobbs, H.H., Jr. 1989. An illustrated checklist of the American crayfishes (Decapoda: Astacidae, Cambaridae, and Parastacidae). Smithsonian Contributions to Zoology 480:1-236.

Inman, T.C., P.C. Marsh, B.E. Bagley, and C.A. Pacey. 1998. Survey of crayfishes of the Gila River Basin, Arizona and New Mexico, with notes on occurrences in other Arizona drainages and adjoining states. Report to US Bureau of Reclamation, Phoenix, Arizona.

Jordan, F., C.J. De Leon, and A.C. McCreary. 1996. Predation, habitat complexity, and distribution of the crayfish Procambarus alleni within a wetland habitat mosaic. Wetlands 16(4):452-457. https://link.springer.com/article/10.1007/BF03161334.

Kouba, A., A. Petrusek, and P. Kozák. 2014. Continental-wide distribution of crayfish species in Europe: update and maps. Knowledge and Management of Aquatic Ecosystems 413(5):1-5.

Mrugala, A., E. Kozubíková, C. Chucholl, S.C. Resino, S. Viljamaa-Dirks, J. Vukic, and A. Petrusek. 2015. Trade of ornamental crayfish in Europe as a possible introduction pathway for important crustacean diseases: Crayfish plague and white spot syndrome. Biological Invasions 17(5):1313-1326. http://link.springer.com/article/10.1007%2Fs10530-014-0795-x

Vanarman, P.G. 2003. Biology and ecology of epigean crayfish that inhabit everglades environments Procambarus alleni (Faxon) and Procambarus fallax (Hagen). Unpublished Ph.D. dissertation. Nova Southeastern University, Fort Lauderdale, FL.

Other Resources:
US Fish and Wildlife Service Ecological Risk Screening Summary for Procambarus alleni

Author: Procopio, J.

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.