The smooth softshell turtle (Apalone mutica ) is a species of softshell turtle of the family Trionychidae. The species is endemic to North America.
The Smooth softshell turtle is a freshwater turtle that is native to North America. It has a smooth, flexible, and leather-like carapace that is covered by skin instead of the hard scutes commonly observed in other turtle species. Its plastron is light (white or gray) with no markings, and the underlying bones are visible. Smooth softshell turtles have a tubular snout with round nostrils. Females of this species are larger than males and are usually brown or olive-colored with irregular dark brown blotches, while the carapace of males and juveniles is a brown or grayish color with dark dots or dashes. Males have thicker tails than females, but females have longer hind claws than males.
Smooth softshell turtles are distributed throughout the central and southcentral United States; their geographic range extends from western Pennsylvania to New Mexico and south to the Florida panhandle. Smooth softshells turtles inhabit the Mississippi River drainage from Louisiana up to North Dakota and Pennsylvania, as well as the Colorado, Brazos, Sabine, and Pearl, Alabama, and Escambia river systems. They prefer medium to large unpolluted rivers with moderate to fast currents but are also found in standing water bodies like lakes, ponds, and marshes. They also favor water with sand or mud bottoms, without rocky areas or dense vegetation. Sandbanks must also be present.
Smooth softshell turtles are solitary diurnal creatures. They are the most aquatic of the softshell turtles as they are often referred to as "swimmers". They are able to stay underwater for extended periods of time due to their long neck and their snout. They often bury themselves in the sand substrate at the bottom of the river or pool just deep enough so that their snout barely reaches the surface. Additionally, the skin covering the shell allows for a high rate of gas exchange. This enables the turtles to stay submerged for a long period of time. In this position, they often wait for prey to pass and utilize their long neck to capture their prey. Smooth softshell turtles hibernate in the months of October to March by burying themselves in substrate underwater. After emerging from hibernation, they are often found on land basking in the sun. Given that their shell is a soft shell, they are unable to stay in the sun for extended periods of time. When basking, they are wary of their surroundings and if any threat presents itself, they are quick to abandon their basking site in seek of safety. Their agility on land and water make them a hard prey for predators. They seek shelter from these threats by diving and concealing themselves in mud.
Smooth softshell turtles are mostly carnivorous (insectivorous, piscivorous), eating aquatic insects, crayfish, fish, and amphibians. However, they sometimes supplement their diet with vegetation such as algae, vegetables, fruits, and nuts.
Smooth softshell turtles are polygynous, meaning that males will mate with more than one female. They typically breed from April to June. Males actively seek out females by approaching other adults. If the other party is male or a non-receptive female, aggression may be displayed. However, if the other party is a receptive female, she remains passive to the advancements of the males. The nesting period is usually from May to July as females only lay eggs once a year. During this period, adult females lay clutches of 3 to 28 eggs not more than 100 m (330 ft) from water in sandy areas. Eggs generally hatch 8-12 weeks later. Hatchlings average a weight of 5.4 g (0.19 oz) and have a carapace length of 4 cm (1.6 in). They are able to feed and care for themselves, once they have hatched and don't require parental care. Males become reproductively mature during their fourth year and females start to breed during their ninth year.
Currently, Smooth softshell turtles are not considered endangered. However, they are facing some wide-ranged threats such as habitat degradation, harvesting for food, and an increase in human disturbances at nesting sites. Additionally, due to their skin's high rate of gas exchange, these turtles are very susceptible to polluted waters.
The IUCN Red List and other sources don’t provide the number of the Smooth softshell turtle total population size. Currently, this species is classified as Least Concern (LC) on the IUCN Red List.
