Disclaimer:

The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

---

Common name: Spiny Softshell

Synonyms and Other Names: Trionyx spiniferus (Le Suer, 1827)

Taxonomy: available through www.itis.gov

Identification: Like most trionychids (softshell turtles), Apalone spinifera (spiny softshell) lacks a hard shell and has a round, flattened, leathery carapace (upper shell). This turtle has a long neck and a snorkel-like, elongated snout with large nostrils containing ridges that extend from each septum (Webb, 1973; Gibbs et al., 2007). The carapace is an olive to light brown color (Behler and King, 1979; Conant and Collins, 1998; Powell et al., 1998). A defining characteristic of the species are the spine-like projections, known as tubercles, which line the anterior edge of the carapace (Conant and Collins, 1998; Collins et al., 2010). Spiny softshell have two prominent black-edged, yellow stripes on each side of the head and neck (Gibbs et al., 2007). The feet are fully webbed, clawed, and have a mottled coloring with black and yellow streaks (Gibbs et al. 2007). Juvenile spiny softshell have black spots or ocelli (eye-like marks) on their carapace, and the outer rim of the shell is pale, cream-colored. Male spiny softshell retain the juvenile markings, while female markings become blotchy grey, olive to brown color with age (Webb, 1973). Most male spiny softshell have small tubercles covering part of the carapace, giving it a sandpaper-like feel, while typical females have a predominantly smooth carapace (Conant and Collins, 1998; Stebbins, 2003; Werner et al., 2004; Ernst and Lovich, 2009). Adult males have a long thick tail with the anal opening near the tip, while females have a short tail situated beneath the carapace (Ernst and Lovich, 2009).

There are currently five recognized subspecies of spiny softshell (Iverson et al., 2008; Collins and Taggart, 2009; Bickham et al., 2007): Gulf Coast spiny softshell (Apalone spinifera aspera, Agassiz, 1857); Texas spiny softshell (A. s. emoryi , Agassiz, 1857); Guadalupe spiny softshell (A. s. guadalupensis, Webb, 1962); Pallid spiny softshell (A. s. pallida, Webb, 1962); and Eastern spiny softshell (A. s. spinifera, Lesueur, 1827). See the following table for differences between the subspecies or see the following for more morphological differences: Conant and Collins (1989), Bonin et al. (2006), and Ernst and Lovich (2009).

Subspecies	Carapace pattern	Carapace spot pattern placement	Carapace rim	Tubercle shapes
Eastern spiny softshell	Thickly-bordered, large black ocelli	Ocelli largest in the middle of carapace	Pale rim with black inner border	Conical
Pallid spiny softshell	Small white spots; ringed black in adult males	Spots not present/obvious on anterior (front)	No distinct border	Conical
Guadalupe spiny softshell	Large white spots; ringed black in adult males	Spots present on anterior and posterior	No distinct border	Round, flat wart-like
Texas spiny softshell	White spots (not ringed with black)	Spots present only on posterior third of carapace	Pale rim, widest posteriorly	Rounded, not prominent (or absent)
Gulf Coast spiny softshell	Black spots and/or ocelli; 2-4 dark lines on posterior carapace	Ocelli largest in the middle of carapace	Pale rim with black inner border	Conical

This species can be mistaken for Apalone mutica (smooth softshell) and A. ferox, the (Florida softshell). Both the smooth softshell and Florida softshell turtles lack the spine-like projections (tubercles) that are present along the anterior edge of the carapace as well as the stripes on the head and neck (Ernst and Lovich, 2009; Beane et al. 2010). Florida softshell also lack strongly patterned feet (Ernst and Lovich, 2009; Beane et al. 2010). Smooth softshell turtles have round nostrils; all other species of softshell turtles have ridges which make the nostrils C-shaped (Powell et al., 2016).

Size: Maximum size females 48 cm, males 24 cm (Webb, 1973)

Native Range:

Apalone spinifera is a wide-ranging species occurring almost continuously throughout the Mississippi Basin from the Gulf of Mexico north to the Upper Midwest. This species can be found east of the Mississippi River as far as New York, with disjunct populations occupying Quebec, Canada, and eastern Vermont. Spiny softshell is native throughout the Coastal Plains from southwestern Virginia and southern North Carolina, ranging southward and westward to the western Panhandle of Florida (Cook, 1984; Conant and Collins, 1998; Hulse et al., 2001; Bonin et al., 2006; Jensen et al., 2008; Ernst and Lovich, 2009; Beane et al., 2010). The western border of the range of spiny softshell extends into river systems from eastern Wyoming, Colorado and New Mexico, including areas in and the Missouri River drainage of Montana (Webb, 1973; Ernst and Lovich, 2009; Hammerson, 1999; Stebbins, 2003; Werner et al., 2004).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Apalone spinifera is an aquatic turtle species that prefers highly-oxygenated rivers, but also inhabits creeks, canals, impoundments, lakes, and oxbows; especially those with a soft sand or mud bottoms (Conant and Collins, 1998; Lindeman, 2001; Stebbins, 2003; Ernst and Lovich, 2009). Sandbars or mud flats are important habitats and are used for basking and nesting (Gibbs et al., 2007). This species is often seen openly basking on logs or floating along the surface but will also spend some time buried in soft sediment with only the head protruding (Ernst and Barbour, 1989; Ernst and Lovich, 2009). While submerged, this species may supplement respiration through gas exchange across the skin and can remain submerged for upwards of 20 minutes (Ernst and Lovich, 2009). Spiny softshell are rarely found far from the water (Gibbs et al., 2007). Spiny softshell are carnivorous, known to consume fish, carrion, crayfish, insects, and a wide variety of invertebrates (Carr, 1952; Ernst and Barbour, 1989; Stebbins, 2003; Ernst and Lovich, 2009).

Male spiny softshell mature around 130 g body weight while females mature around 15 kg (Robinson and Murphy, 1978). Females lay 4-39 eggs per clutch, with an average of 12-18 eggs. Nesting occurs during late spring and throughout summer, nests are excavated in soil exposed to sunlight, often in close proximity to water on nearby sand or gravel bars, however, nests can be placed further away from water depending on the availability of ideal nesting habitat (Ernst and Barbour, 1989; Jensen et al., 2008; Ernst and Lovich, 2009). Incubation lasts 2 to 3 months (dependent on ambient conditions), and unlike the majority of other turtles, the sex of hatchlings is determined genetically rather than by temperature, producing clutches with similar proportions of male and female hatchlings (Gibbs et al., 2007; Jensen et al., 2008). Female spiny softshell become sexually mature in 4-5 years (Gibbs et al., 2007), and have lived more than 20 years in captivity (Jensen et al., 2008).

Means of Introduction: Most spiny softshell are introduced through the release of pets (Haffner, 1997; Kraus, 2009; Krysko et al., 2011), but there are also illegal stockings and translocations during aquaculture operations (Conant, 1961). Spiny softshell found in the Maurice River system of New Jersey were intentionally introduced from Indiana to establish a local breeding population (Conant, 1961).

Status: Outside of its native range, spiny softshell are established in various lakes and rivers in Arizona, California, Massachusetts, New Jersey, New Mexico, Nevada, and Utah. Some of the larger river systems that this species is established include: Colorado River, Connecticut River, Gila River, Maurice River, San Diego River, and San Joaquin River. Spiny softshells are established on Oahu, Hawaii.

Impact of Introduction: As of yet, this species has not been adequately studied or evaluated to determine what ecological consequences, if any, have resulted from its introduction into the USA or elsewhere. To better understand and adequately assess the possible types and magnitude of any suspected ecological and economic impacts would most likely require further field and laboratory research, along with a review of any possible new literature on the subject. 

Remarks: The taxonomy of A. spinifera has been reviewed or summarized by Webb (1973, 1990), Meylan (1987), Iverson et al. (2008), Weisrock and Janzen (2000), Collins and Taggart (2009), Bickham et al. (2007), and Ernst and Lovich (2009). Summaries on the literature and natural history of spiny softshells can be found in Webb (1973), Ernst and Barbour (1989), Bonin et al. (2006), Ernst and Lovich (2009), and Collins et al. (2010).

Apalone spinifera is difficult and dangerous to handle because of its sharp claws, sharp, powerful jaws and long protrusive neck; they are quick to defend themselves (Carr, 1952; Werner et al., 2004; Collins et al., 2010), and are aggressive toward members of the same species (conspecifics) (Ernst and Lovich, 2009).

Apalone spinifera has been classified at a risk level of “serious” as a nonindigenous species that could become established in the European Union (Kopecký et al. 2013).

References: (click for full references)

Beane, J. C., A. L. Braswell, J. C. Mitchell, W. M. Palmer, And J. R. Harrison III. 2010. Amphibians and Reptiles of the Carolinas and Virginia. Second Edition, Revised and Updated. The University of North Carolina Press, Chapel Hill. 274 pp.

Behler, J. L., and F. W. King. 1979. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, Inc., New York. 743 pp.

Bickham, J. W., J. B. Iverson, J. F., Parham, H.-D. Philippen, A. G. J. Rhodin, H. B. Shaffer, P. Q. Spinks, and P. P. van Dijk. 2007. An annotated list of modern turtle terminal taxa with comments on areas of taxonomic instability and recent change. Chelonian Research Monographs 4:173-199.

Bonin, F., B. Devaux, and A. Dupré. 2006. Turtles of the World. [English Edition.] The Johns Hopkins University Press, Baltimore. 416 pp.

Carr, A. 1952. Handbook of Turtles. The Turtles of the United States, Canada, and Baja California.  Comstock Publishing Associates, Ithaca and London. 542 pp.

Collins, J. T., S. L. Collins, and T. W. Taggart. 2010. Amphibians, Reptiles, and Turtles in Kansas. Fourth Edition. Eagle Mountain Publishing, LC, Eagle Mountain, Utah. 312 pp.

Collins, J. T., and T. W. Taggart. 2009. Standard Common and Current Scientific Names for North American Amphibians, Turtles, Reptiles & Crocodilians. Sixth Edition. The Center for North American Herpetology, Lawrence, Kansas. 44 pp.

Conant, R. 1961. The softshell turtle, Trionyx spinifer, introduced and established in New Jersey. Copeia 1961(3):355-356.

Conant, R., and J. T. Collins. 1998. A Field Guide to Reptiles & Amphibians. Eastern and Central North America. Third Edition, Expanded. Houghton Mifflin Company, Boston. 616 pp.

Ernst, C. H., and R. W. Barbour. 1989. Turtles of the World. Smithsonian Institution Press, Washington, D.C. and London. 313 pp.

Ernst, C. H., and J. E. Lovich. 2009. Turtles of the United States and Canada. Second Edition. The Johns Hopkins University Press, Baltimore. 827 pp.

Gibbs, J. P., A. R. Breisch, P. K. Ducey, G. Johnson, the late J. Behler, and R. Bothner. 2007. The Amphibians and Reptiles of New York State (Identification, Natural History, and Conservation). Oxford University Press, New York, NY.

Haffner, P. 1997. Bilan des introductions récentes d’amphibiens et de reptiles dans les milieux aquatiques continentaux de France métropolitaine. Bulletin de Français de la Pêche et de la Pisciculture 344/345:155–163.

Iverson, J. B., P. A. Meylan, and M. E. Seidel. 2008. Testudines—turtles. Pp. 67-74. In: B. I. Crother (chair), and Committee on Standard English and Scientific Names (editors). Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Sixth Edition. Society for the Study of Amphibians and Reptiles Herpetological Circular 37:1-84.

Jensen, J. B., C. D. Camp, W. Gibbons, and M. J. Elliott. 2008. Amphibians and Reptiles of Georgia. 1st edition. The University of Georgia Press, Athens, GA.

Kopecký, O., L. Kalous, and J. Patoka. 2013. Establishment risk from pet-trade freshwater turtles in the European Union. Knowledge and Management of Aquatic Ecosystems 410(2).

Kraus, F. 2009. Alien Reptiles and Amphibians. A Scientific Compendium and Analysis. Springer, [Dordrecht]. 563 pp. + CD-ROM.

Krysko, K. L., J. P. Burgess, M. R. Rochford, C. R. Gillette, D. Cueva, K. M. Enge, L. A. Somma, J. L. Stabile, D. C. Smith, J. A. Wasilewski, G. N. Kieckhefer III, M. C. Granatosky, and S. V. Nielsen. 2011. Verified non-indigenous amphibians and reptiles in Florida from 1863 through 2010: Outlining the invasion process and identifying invasion pathways and status. Zootaxa 3028:1-64 + MorphoBank Project No. p536: URL: http://www.morphobank.org.
Lindeman, P. V.  2001.  A contrast in the basking habits of the sympatric trionychids turtles Apalone mutica and A. spinifera. Herpetological Natural History 8(1):87-89.

Meylan, P. A. 1987. The phylogenetic relationships of soft-shelled turtles (Family Trionychidae). Bulletin of the American Museum of Natural History 186(1):1-101.

Powell, R., J. T. Collins, and E. D. Hooper, Jr. 1998. A Key to Amphibians & Reptiles of the Continental United States and Canada. University Press of Kansas, Lawrence. 131 pp.

Powell, R., R. Conant, and J.T. Collins. 2016. Peterson field guide to reptiles and amphibians of eastern and central North America. 4 edition. Houghton Mifflin Harcourt Publishing Company, New York, NY.

Robinson, K.M., and G.C, Murphy. 1978. The reproductive cycle of the eastern spiny softshell turtle (Trionyx spiniferus spiniferus). Herpetologica 34:137-140.

Stebbins, R. C. 2003. A Field Guide to Western Reptiles and Amphibians. Third Edition. Houghton Mifflin Company, Boston. 533 pp.

Webb, R. G. 1990. Trionyx. Catalogue of American Amphibians and Reptiles 487:1-7.

Webb, R. G. 1973. Trionyx spiniferus. Catalogue of American Amphibians and Reptiles 140:1-4.

Weisrock, D. W., and F. J. Janzen. 2000. Comparative molecular phylogeography of North American softshell turtles (Apalone): Implications for regional and wide-scale historical evolutionary forces. Molecular Phylogenetics and Evolution 14(1):152-164.

Other Resources:
A Field Guide to Amphibians and Reptiles in Coastal Southern California - USGS

Animal Diversity Web: Eastern spiny softshell turtle - University of Michigan Museum of Zoology

Marshall University. 2003. Turtles of West Virginia, Eastern Spiny Softshell, Apalone spiniferus spiniferus

Author: Daniel, W.M., C.M. Morningstar, and L.A. Somma

Peer Review Date: 3/1/2019

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.