![[Cambarus diogenes]](cdiogenes.jpg)
Cambarus diogenesDevil CrayfishDESCRIPTIONThe Devil Crayfish is also referred to as the Meadow crayfish. It is a large, burrowing, semi-terrestrial crayfish, distinguished from similar species (Chimney Crayfish) by lack of notch on movable finger of chela and lateral continuation of the cervical groove. Colouring is dark reddish-brown to olive green with orange-red margins of chelipeds.HABITATBurrows in coastal wetlands, mudflats, wet meadows and marshes.DISTRBUTIONCanada/OntarioThe Devil Crawfish is found only in southwestern Ontario where it is at the very extreme edge of its northernmost range. The Canadian range was recently extended westward to the Niagara Peninsula by Guiasu et al., (1996). Hamr (unpublished)has found new sites on the northern portion of the Long Point Peninsula suggesting the viability of those cited by Crocker and Barr (1968). The Canadian range of the species covers approximately 4,500 km2(1,737 mi.2) an area of about 300 km (186 mi.) wide (Guiasu et al., 1996). The northern limit of the species appear to be about 43¡N although one anomalous record exists from northern Ontario (Rainy River District near Atikokan, 48¡N) (Crocker and Barr, 1968). The limited distribution of this species in Canada is probably a function of the combination of possible competition with the more abundant and closely related Chimney Crayfish and as yet unidentified environmental constraints (Crocker and Barr, 1968; Guiasu et al., 1996). North America The species is wide ranging in the southern half of North America. It is found in Ontario, Michigan, Minnesota, Wisconsin, Ohio, Pennsylvania, Kentucky; Delaware, Illinois, New York, New Jersey, Indiana, Maryland, District of Columbia, West Virginia, Tennessee, North Carolina, Georgia, Florida, Alabama, Mississippi, Louisiana, Arkansas, Missouri, Iowa, Nebraska, Kansas, South Dakota, North Dakota, Oklahoma, Texas, Colorado, Wyoming and Montana (Hobbs, 1989; Page, 1985; Taylor et al., 1996). ECOLOGYThe Devil Crawfish appears to be an obligate burrower in Ontario, constructing burrows in coastal wetlands, mudflats, wet meadows and marshes (Crocker and Barr, 1968; Guiasu et al., 1996). The burrows are usually capped with mud chimneys, but these may not be present where the ground is very soft and moist. In Ontario, burrows are generally shallower than those of Chimney Crayfish. The chimneys may be quite high (up to 15 cm/5.85 in.) and the diameter of the burrows may be very large depending upon the size of the occupant (Hamr, unpublished). Oxygen concentrations of burrow water can range between 0.1-8.8 mg/l (0.1-8.8 ppm); temperature 17-27¡C (63-81¡F); pH from 5.2-9.0) (Hobbs III and Jass, 1988). Devil Crawfish can take oxygen directly from the air by exposing its gills to the air-water interface or crawling into chimneys and/or tunnels which are above the water table. It can also survive in air for prolonged periods as long as its gills are covered by a thin film of moisture. Although it lives in similar habitats, the Devil Crawfish has never been found together with Chimney Crayfish in Ontario (Guiasu et al., 1996).LIFE HISTORYLittle is known of the life history of this species in Ontario as no published studies exist. Copulation can occur within burrows or in open water. Hamr (unpublished)found Form I males and females with strong glair gland development in early May and also observed oviposition in captivity at that time. He also observed moulting activity in adults in August. Maturity is reached probably at CPLs in excess of 40 mm (1.56 in.), and maximum size is 61 mm (2.38 in.) CPL.CONSERVATION STATUSThe range of this species overlaps areas of intense agricultural and recreational activity and, as in the case of the Chimney Crayfish, its habitat is likely under threat because of wetland destruction and alteration. To prevent further habitat shrinkage, populations of this species should be identified and their habitats should be protected. Because of the vulnerability of their habitat Devil Crawfish should be classified as "Vulnerable" in Canada. It is fortuitous that one of the known distribution points is found within a federally protected area (Long Point National Wildlife Area Ð Canadian Wildlife Service).(Used by permission: text by Premek Hamr, modified from "Baitfish of North America"2007 painting by Aleta Karstad) |