Spiny softshell turtles have soft, flat, rounded carapaces without scutes. The edges are pliable with small spines, in the eastern subspecies the spines are toward the front of the carapace. Some subspecies have the spines on the posterior part of the carapace (A. s. pallida) while some have them on most parts of the carapace (Behler and King 1998). The nose is long, tapered, and upturned at the end with ridges (Harding 1997). Unlike gulf spiny soft-shell turtles (A. s. aspera), with two distinct black-bordered yellow stripes on each side of the head that come together before the long neck, eastern spiny soft-shell turtles (A. spinifera spinifera) have two black-bordered yellow stripes that travel along the neck and do not connect (Conant and Collins 1998). The plastron is whitish or yellow with bones visible underneath. They have claws and their feet are webbed for swimming. The body is olive or tan with black speckles and a dark rim around the edge of their carapace. In A. s. aspera two or more dark lines can be found bordering the rear margin of the shell and in A. s. pallida, the black ring is lacking. Some subspecies have whitish spots on their whole carapace, the posterior half of their carapace, or on the rear third of their carapace, these subspecies being A. s. guadalupe, A. s. pallida, and A. s. emoryi respectively. These characteristics intergrade where hybrid zones occur. There is some sexual dimorphism. Adult males retain the juvenile's olive and yellow coloration with black "eyespots", have a slightly rougher carapace than females, and are smaller than females, with a carapace length of 12.7 to 24 cm. Males also have longer and thicker tails that females. The carapace of females darkens during adulthood and becomes a mottled gray. The length ranges from 24 to 48 cm and the tail barely extends past the edge of her carapace. (Conant and Collins, 1998; Harding, 1997)
In courtship, males 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 most other turtles). (Conant and Collins, 1998; Harding, 1997)
Females invest energy into supplying their eggs with nutrients for development and deposit them into a safe nest. Once the eggs are laid there is no further parental investment. (Harding, 1997)
Spiny softshell turtles are diurnal animals, spending most of the day basking in the sun and foraging for food. They can be spotted sunning on logs and river banks. If disturbed, they will quickly retreat into the water and bury themselves in sand, leaving only their heads visible. These turtles are also able to breathe underwater for extended periods through their pharyngeal lining, cloacal lining, and skin. Spiny softshell turtles spend October to April in the water buried underneath substrate in a state of dormancy. (Behler and King, 1998; Harding, 1997)
Spiny softshell turtles use their sense of vision and touch to find prey. When they mate they respond to tactile stimulation. (Harding, 1997)
preys on on various macroinvertebrates such as aquatic insects, crayfish, and occasionally a fish. They find their food underneath objects, along the floor of the lake, and in vegetation. They also hide in the floor substrate and grab prey as they swim by (Harding 1997).
Spiny softshell turtle nests are often destroyed by raccoons, skunks, and foxes. Young softshell turtles are eaten by raccoons, herons, and fish. Adults are killed and eaten only by humans, they have few natural predators. When bothered, spiny softshell turtles will extend their long necks and snap viciously at their attacker, inflicting a painful bite. They are wary and can hide themselves quickly. (Harding, 1997)
Spiny softshell turtles are important predators in aquatic systems, impacting populations of crustaceans and aquatic insects.
Spiny softshell turtles are important members of the ecosystems where they live. They prey on aquatic insects and crustaceans.
Spiny softshell turtles are sometimes marketed for human consumption and some places have made laws dealing with catch limits, catch seasons, as well as size limitations. (Harding, 1997)
It was once thought that spiny softshell turtles damaged game fish populations. However, all data shows that these animals have no impact on game fish populations or humans whatsoever. If handled, they can aggressively defend themselves and inflict painful bites. (Harding, 1997)
Because (Harding, 1997)respire aquatically with pharyngeal gill slits and cloaca, they are vulnerable to Rotenone, a chemical that is used to kill unwanted fish. Rotenone hinders oxygen absorption and many soft shell turtles are now gone from Rotenone contaminated waters in the Great Lakes. Habitat fragmentation and shoreline development continues to threaten nesting sites. Along with other turtles, is hunted or shot for "fun" and human consumption. Eggs, hatchlings, and juveniles are threatened by various human activities and vulnerable to predators such as raccoons, foxes, and skunks, all of which thrive in areas of human development. They are not listed as endangered, vulnerable, or threatened by the IUCN, CITES, or the U.S. Endangered Species Act.
Spiny softshell turtles were previously known as Trionyx spiniferus. There are several subspecies including Eastern, Western, Gulf Coast, Pallid, Guadalupe, and Texas. (Behler and King, 1998; Conant and Collins, 1998)
David Armitage (editor), Animal Diversity Web.
Pamela Bartholomew (author), Michigan State University, James Harding (editor), Michigan State University.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
A substance that provides both nutrients and energy to a living thing.
mainly lives in water that is not salty.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.
An animal that eats mainly insects or spiders.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
movements of a hard surface that are produced by animals as signals to others
uses sight to communicate
Behler, J., F. King. 1998. National Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, Inc..
Conant, R., J. Collins. 1998. A Field Guide to Reptiles and Amphibians; Eastern and Central North America. New York: Houghton Mifflin Co..
Harding, J. 1997. Amphibians and Reptiles of the Great Lakes Region. Ann Arbor: University of Michigan Press.