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Gulf Coast Spiny Softshell

Apalone spinifera

What do they look like?

Spiny softshell turtles have soft, flat, rounded carapaces (shells) without large scales. The edges are soft with small spines. The nose is long and upturned. The underbelly 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 shell. Adult males have olive and yellow coloration on their carapaces, with black "eyespots", and a thicker tail tham females. Males are also smaller than females, with a shell length of 12.7 to 24 cm. Females are 24 to 48 cm in length, with dark carapace and a small tail that doesn't go beyond the edge of their carapaces.

  • Sexual Dimorphism
  • female larger
  • sexes shaped differently
  • Range length
    12.7 to 48 cm
    5.00 to 18.90 in

Where do they live?

Spiny softshell turtles occupy areas from central-eastern U.S. (western New York and southern Carolina) to Wisconsin, Minnesota, and southern Ontario, and as far south as Mexico. (Conant and Collins, 1998)

What kind of habitat do they need?

Spiny softshell turtles inhabit various freshwater sources such as rivers, lakes, marshes, farm ponds, as well as bays of the Great Lakes. They prefer open habitats with a small amount of vegetation and a sandy or muddy bottom and require sandy raised nesting areas close to water. (Behler and King, 1998; Harding, 1997)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams

How do they grow?

Sex is not determined by temperature variations in A. spinifera. (Behler and King, 1998; Harding, 1997)

How do they reproduce?

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)

Spiny softshell turtles reach adulthood between the ages of 8 to 10 years old. They mate in mid to late spring in deep water. Female spiny softshell turtles lay their clutches along a sunny sandbar or gravel bank in a cavity that they dig close to water as quickly as possible (usually within an hour). Spiny softshell turtles sometimes nest more than once during a season. They lay between 9 and 38 round eggs which hatch from August to September. Clutches can even incubate through the winter and hatch in the spring. (Behler and King, 1998; Harding, 1997)

  • How often does reproduction occur?
    Breeding occurs once yearly, sometimes several times in a year.
  • Breeding season
    Spiny softshell turtles mate in mid to late spring.
  • Range number of offspring
    9 to 38
  • Range age at sexual or reproductive maturity (female)
    8 to 10 years
  • Range age at sexual or reproductive maturity (male)
    8 to 10 years

Females give their eggs enough nutrients for development and put them into a safe nest. Once the eggs are laid there is no more parental care.

  • Parental Investment
  • no parental involvement
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female

How long do they live?

Estimated longevity in spiny softshell turtles is up to fifty years in a large female. (Conant and Collins, 1998; Harding, 1997)

  • Range lifespan
    Status: wild
    50 (high) years

How do they behave?

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 of time. Spiny softshell turtles spend the months of October to April underwater, buried in the mud or sand in a state of dormancy. (Harding, 1997)

How do they communicate with each other?

Spiny softshell turtles use their sense of vision and touch to find prey. (Harding, 1997)

What do they eat?

Spiny softshell turtles prey on invertebrates such as aquatic insects, crayfish, and occasionally preys upon 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 it swims by. (Harding, 1997)

  • Animal Foods
  • amphibians
  • fish
  • insects
  • mollusks
  • terrestrial worms
  • aquatic crustaceans

What eats them and how do they avoid being eaten?

Spiny softshell turtle nests are often destroyed by raccoons, skunks, and foxes. Young softshell turtles are eaten by raccoons, herons, and large 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 shy and will quickly dive and hide under mud and sand to avoid predators.

  • These animal colors help protect them
  • cryptic

What roles do they have in the ecosystem?

Spiny softshell turtles are important members of the ecosystems where they live. They prey on aquatic insects and crustaceans.

Do they cause problems?

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)

  • Ways that these animals might be a problem for humans
  • injures humans
    • bites or stings

How do they interact with us?

In some areas these turtles are harvested as food for humans.

  • Ways that people benefit from these animals:
  • food

Are they endangered?

Populations of spiny softshell turtles are damaged by Rotenone, a chemical designed to kill fish. Habitat destruction and shoreline development continues to threaten nesting sites. They are not listed as endangered, vulnerable, or threatened by the IUCN, CITES, or the U.S. Endangered Species Act. (Harding, 1997)

Some more information...

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)

Contributors

David Armitage (editor), Animal Diversity Web.

Pamela Bartholomew (author), Michigan State University, James Harding (editor), Michigan State University.

References

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.

 
University of Michigan Museum of ZoologyNational Science Foundation

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Bartholomew, P. 2008. "Apalone spinifera" (On-line), Animal Diversity Web. Accessed September 01, 2014 at http://www.biokids.umich.edu/accounts/Apalone_spinifera/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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