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The distribution of the Western Spiny Softshell lies in drainages throughout the plains of the Midwest, from Montana east to Minnesota and south into Oklahoma and Arkansas. In Wyoming this species inhabits the permanent waters of lakes and rivers and larger streams of eastern counties and the Big Horn Basin.
They are usually seen basking (pointed headfirst toward the water) on sandbars, partially submerged rocks and logs, and along lakeshores and riverbanks; they are extremely wary and make a hasty retreat to the water at the slightest concern. A careful observer may spot the two-lobed proboscis of their snout protruding from the water’s surface as they snorkel their surroundings; they promptly swim to deeper water if they find their view the least suspicious. Caution: when handled, they will hiss, scratch, and inflict a painful bite if given the chance; their neck is longer and more agile than one might think and they can quickly dart the head out and accurately snap off a nasty bite with startling speed.
They are primarily diurnal, active from April into October, and, being opportunistic feeders, they forage on foods such as crayfish, insects, fish, carrion, and occasionally vegetation. Normal respiration occurs via well developed lungs, but while underwater it is supplemented with gas exchange taking place through the thin and highly vascular linings of the cloaca and the buccal cavity of the mouth and throat. They may migrate overland from drying ponds to other areas, but they are seldom found far from water and are readily dehydrated.
These are large turtles with carapace lengths (CL) of adult males reaching 7 inches and females up to 18 inches. They are easily recognized by the pancake appearance of the carapace, which is composed of a leathery hide rather than the more conventional looking plate-like scales (scutes) associated with other turtle species. The carapace is soft and somewhat flexible with the leading edge containing spiny tubercles. This upper shell has an olive background that is covered with numerous black spots (ocelli, eye-like) and is bordered by a thin black line with a wider yellow lip running around the perimeter. The smaller plastron is white and often translucent enough to reveal some of the underlying bones. Their three-clawed and paddle-like feet are extensively webbed. The tail is somewhat short and does not extend much beyond the rear of the shell. The long narrow head has a tubular snout that terminates with the paired nostrils. They lack teeth but have a sharp and hard edged beak lying behind fleshy lips.
Nest building and egg laying occurs in early summer. In the daylight the female leaves the water and moves to a nearby area where she uses her hind feet to excavate a 10 inch deep hole in sand or small gravel. She lays about 20 hard shelled eggs (1.5 inches in diameter) and covers the cavity with soil before returning to the water—completing her maternal role. The eggs are heavily preyed upon by skunks and raccoons during the following 2-3 month incubation. Those surviving predation require only the warmth of the sun before hatching occurs. (Hatchlings do not overwinter in the nest.) Sexual maturity is reached when males reach lengths of about 5 inches (4-5 years) and females about 10 inches (8-9 years).