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84 The chela or claw of the Rusty crayfish look like a cross between those of the Northern and Ringed crayfishes. The movable finger (dactyl) has a double curve like that of the Northern crayfish. They are similar to those of the Ringed crayfish in that they are smooth with few tubercles, have a large gap and there are no setae between the fingers. Also, the tips of the fingers have a black ring at the tip similar to that of the Ringed crayfish. There are no keys that will work to identify female crayfish. They are identified by their association with and similarity to male crayfish collected from the same location. That is because the main sex characteristic, the annulus ventralis, is very similar between species. Now, given that, since we only have six species in the state of Nebraska, the secondary characteristics noted above will often work with females as will the annulus ventralis.. This photo illustrates the annulus ventralis of a Rusty crayfish female. Note also the genital pores at the bases of the third periopods just above. HABITATS The Rusty crayfish is found in a wide variety of habitats including creeks, rivers, reservoirs and lakes of all sizes and on all types of substrates. They are often found under rip rap, rocks, woody debris, logs or rooted vegetation. They can be found in waters varying from a few centimeters in stream riffles to 15 m in large lakes. The Rusty crayfish is considered to be a tertiary burrower that burrows only when necessary, if then. In aquarium tests, where water levels were gradually lowered to simulate natural drying, only 45% of the adult and 76% of juvenile Rusty crayfish dug a burrow. 12 Rusty crayfish are habitat generalists meaning they will do fine in most any waters. In Wisconsin, the nonnative Rusty crayfish successfully colonized a wide variety of habitats. These included: soft bottomed lakes and pools, rubble bottomed lakes, and swift streams with and without weed beds. They were collected from quiet waters and moderately fast streams that were clear or turbid. 110 In Iowa, typical habitats for Rusty crayfish were rocky pools and riffles in small,