Description: The spiny softshell turtle's scientific name is very descriptive of the animal. Apalone comes from the Greek word apalos, meaning soft or tender, and spinifera is of Latin origin; spina- referring to thorn or spine and -ifer meaning bearing. This species is a member of the family Trionychidae, and one of the most distinguishing features of members in this family is the presence of a leathery, moderately flexible carapace. This is caused by loss of keratinized scutes and some bony tissue loss. Spiny softshell turtles have webbed feet, each with three claws. Another distinguishing feature of softshell turtles is the presence of a fleshy, elongated nose.
The carapace (the upper part of the shell) ranges from brown or yellow-brown to olive in color, while the plastron (lower part of the shell) is lighter, usually white or yellow. Hatchlings usually have dark spots on the carapace, but as females age, they frequently become darker in color, or their carapace becomes splotched. Males tend to maintain the same coloration pattern from birth. Coloration also varies between each subspecies, and the exact coloration can also depend on an individual turtle's environment. Spiny softshell turtles are cryptically colored, meaning that their coloration helps them blend in with their surrounding environment.
Spiny softshell turtles also have pale lines bordered by black lines running from its head down the side of its neck. The carapace length ranges from 7.1 to 21.3 inches, with females growing larger than males. The namesake spines are found along the anterior border of the carapace and are more commonly found in males. The variation in coloration, size, and spine presence indicates that this species exhibits sexual dimorphism.
Habitat: Spiny softshell turtles are often referred to as ecological generalists, meaning that they are found in a wide variety of habitats. The spiny softshell can be found in bodies of fresh water including ponds, lakes, rivers, tributaries, and streams. They can persist in more urban environments as they are well adapted to periodic habitat disturbances. They inhabit shallow water less than 3 feet 3 inches deep, but can also be found as far as 33 feet deep. When swimming, a study suggests that they get most of their thrusting power from their forelimbs as opposed to their hindlimbs, which is common in other species. They can be found in areas with varying levels of vegetation, and although they are generally found in more slow moving waters, this species abundance is greatest in waters with higher visibility and slower water velocity. Spiny softshells prefer waters with sandy bottoms and clean, sandy banks. Sandy environments are important for nesting sites, proper juvenile growth and development, and camouflage. Spiny softshells migrate between warm and cold seasons.
Range: This species is the most widely distributed softshell turtle in North America. This could be due to habitat fragmentation caused by humans. The spiny softshell has a wide range, extending throughout much of the United States, as well as north into the Canadian provinces of Ontario and Quebec, and south into the Mexican states of Tamaulipas, Nuevo León, Coahuila and Chihuahua. As of recently, the spiny softshell has expanded its geographic range into Washington State and California. They were also recently discovered in Lake Champlain despite the historical records.
Diet: Spiny softshell turtles feed on a variety of food items. They are primary consumers and feed on invertebrates (crayfish and aquatic insects), fish, algal stocks and other plant material, and mussels. They are generally observed as benthic feeders; they can either actively hunt prey or bury themselves in the sand and wait to ambush prey.
Reproduction: Spiny softshells begin mating between ages 8 and 10. A large female turtle may live up to 50 years. The turtles mate in mid-to-late spring in deep water. The male will nudge the female's head while swimming, and if she chooses to mate, the male will swim above the female without clasping her with his claws (unlike other turtles). Prior to nesting, the females have been observed to have a 3 stage activity pattern throughout the day. The females start the day by basking and moving around an area, then they spend a majority of their afternoon swimming in a new area, and finally they would stop and search for an ideal nesting spot. A few months later, the female turtle quickly lays her eggs along a sunny sandbar or gravel bank in a flask-shaped cavity she has dug close to the water. This nesting behavior typically begins around July with the females leaving the water and probing the ground with her snout to find the spot to lay her eggs. The turtle nests more than once during a single season. She can lay between 9 and 38 round, calcareous-shelled eggs. The eggs are laid around July and September, and they hatch in the spring. Larger bodied females have been found to lay a second clutch in late June or July. In studies observing nesting behavior, it has been found that the females are more likely to lay eggs on days where there is a small difference between the air and water temperatures. Unlike in some other turtles, in the spiny softshell turtle, the sex of the hatchlings is not determined by temperature variations; it is determined by genetics.
Status: Widespread, cryptic and locally common species with an adaptable life history and high reproductive potential by turtle standards. Harvest rates appear not significant enough to have led to documented localised declines. It is listed as Least Concern.
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Disclaimer: ITIS taxonomy is based on the latest scientific consensus available, and is provided as a general reference source for interested parties. However, it is not a legal authority for statutory or regulatory purposes. While every effort has been made to provide the most reliable and up-to-date information available, ultimate legal requirements with respect to species are contained in provisions of treaties to which the United States is a party, wildlife statutes, regulations, and any applicable notices that have been published in the Federal Register. For further information on U.S. legal requirements with respect to protected taxa, please contact the U.S. Fish and Wildlife Service.
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