Overview

Distribution

Smooth softshell turtles are native to temperate areas of North America, ranging throughout the central and south-central United States. Their range extends from Pennsylvania to New Mexico and south to the Florida panhandle. This species is thought to have been extirpated from Pennsylvania. Smooth softshell turtles are believed to have occurred in North America since the Cretaceous Period, although this is not yet supported by fossil evidence. Smooth softshell turtles have also been introduced to France.

Two subspecies of smooth softshell turtles have been identified. Midland smooth softshells, Apalone mutica mutica, are found throughout the central United States, while Gulf coast smooth softshells, Apalone mutica calvata, range from Louisiana to the panhandle of Florida.

Biogeographic Regions: nearctic (Native ); palearctic (Introduced )

  • Ernst, C., J. Lovich. 2009. Turtles of the United States and Canada. Baltimore, Maryland: The John Hopkins University Press.
  • Ernst, C., R. Barbour, J. Lovich. 1994. Turtles of the United States and Canada. Washington D.C.: Smithsonian Institution Press.
  • Hulse, A., C. McCoy, E. Censky. 2001. Amphibians and reptiles of Pennsylvania and the Northeast. Ithaca, New York: Cornell University Press.
  • Oldfield, B., J. Moriarty. 1994. Amphibians & Reptiles Native to Minnesota. Minneapolis, Minnesota: University of Minnesota Press.
  • Quammen, R. 1992. A latest Cretaceous (Maestrictian) lower vertebrate faunule from the Hell Creek Fromation of North Dakota. Proceedings of the North Dakota Academy of Science, 46: 41.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© The Regents of the University of Michigan and its licensors

Source: Animal Diversity Web

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Range Description

Apalone mutica inhabits the greater Mississippi basin from Louisiana up to North Dakota, Minnesota and western Pennsylvania, as well as the Colorado, Brazos, Sabine, and Pearl, Alabama and Escambia river systems (Webb 1973, Iverson 1992).

Apalone mutica mutica
: Mississippi basin, and western rivers to central Texas;

Apalone mutica calvata
: Pearl, Alabama and Escambia river systems.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

endemic to a single nation

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Global Range: Gulf Coast from western Florida to eastern Texas, north to eastern New Mexico, southern South Dakota, Wisconsin, and northwestern Pennsylvania.

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Continent: North-America
Distribution: USA (Ohio, Minnesota, S North Dakota, South Dakota, E/S Nebraska, Kansas, Oklahoma, N/E Texas, Mississippi, Missouri, Iowa, Arkansas, Louisiana, Illinois, Wisconsin, Indiana, Kentucky, Tennessee, Alabama, W Florida Panhandle, E New Mexico; Considered extirpated in W Pennsylvania)  calvata: Mississippi;
Type locality: Pearl River, Roses Bluff, 14 mi E Jackson, Rankin County, Mississippi; W. F. Childers; August 25, 1952.  
Type locality: "Newharmony, sur le Wabash" (=New Harmony, Wabash River), Posey County, Indiana, USA
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Peter Uetz

Source: The Reptile Database

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Physical Description

Morphology

Smooth softshell turtles are medium to large freshwater turtles. Females have a back shell that is 16.5 to 35.6 cm long. Females are larger than males, who have a shell that is 11.5 to 26.6 cm long. Like other softshell turtles, smooth softshell turtles have a carapace that is covered by skin instead of the hard scutes commonly observed in other turtle species. The carapace is ovoid and lacks spines on the front edge. The coloring of the carapace ranges from olive to orange. Females typically have a tan or brown carapace, while males have a brown or gray carapace. Both sexes have dark markings (spots, streaks, or blotches) on their carapace, although females typically have a blotchier pattern. The plastron is light (white or gray) with no markings, and the underlying bones are visible. Dorsal coloration of an individual's head, limbs, and tail are similar to that of its carapace. A cream or orange line bordered in black extends from the back of each eye to the neck. Juvenile smooth softshell turtles do not differ in coloration from adults, but juveniles of subspecies are used to tell them apart in the field. Hatchlings have a brown or olive carapace with many markings on the carapace.

Smooth softshell turtles have a tubular snout with round nostrils that are usually positioned inferior, and they lack a septal ridge. Male smooth softshell turtles have thicker tails than females, a trait commonly observed in turtle species. In males, the anal vent is located near the tip of the tail, while in females, the anal vent is usually located near the edge of or under the carapace. As with other species of turtles, female smooth softshells have longer hind claws than males, which have longer foreclaws than females.

Smooth softshell turtles are the most aquatic of all North American softshells. Their aquatic nature is made possible by a variety of behavioral and morphological adaptations. The skin covering the shell causes a high rate of water exchange. Water exchange in freshwater is typically 6.3 mL/100g wet BM/hour. The lining of the cloaca and pharynx enables uptake of oxygen from the water. Furthermore, the surface of their shell and skin is cutaneous, increasing the permeability of gases and water. For instance, smooth softshell turtles lose about 64% of respiration-produced carbon dioxide through their skin. Their long neck and snout contribute to the ability to remain submerged for extensive periods of time.

Smooth softshell turtles are mostly easily confused with spiny softshell turtles (Apalone spinifera). The two species, however, can be distinguished by examining the carapace. Spiny softshells have spines along the front edge of their carapace, and the carapace usually has a sandpaper texture. Smooth softshells lack these characteristics. Spiny softshells, as with most softshell turtles, also have a septal ridge in the nose. However, smooth softshells lack a septal ridge. Distinguishing features of other softshell species include heavily marked limbs and spines on the carapace.

Range length: males 11.5 cm; females 16.5 to males 26.6 cm; females 35.6 cm.

Sexual Dimorphism: female larger; sexes colored or patterned differently

Other Physical Features: ectothermic ; bilateral symmetry

  • Jackson, D., J. Allen, P. Strupp. 1976. The contribution of non-pulmonary surfaces to CO2 loss in 6 species of turtles at 20 C. Comparative Biochemistry and Physiology, 55A: 243-246.
  • Minnesota Department of Natural Resources, 2011. "Apalone mutica" (On-line). Minnesota Department of Natural Resources. Accessed April 03, 2011 at http://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=ARAAG01020.
  • Stone, P., J. Iverson. 1999. Cutaneous surface area in freshwater turtles. Chelonian Conservation and Biology, 3: 512-515.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© The Regents of the University of Michigan and its licensors

Source: Animal Diversity Web

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Size

Length: 36 cm

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Type Information

Paratype for Apalone mutica calvata
Catalog Number: USNM 7655
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Sex/Stage: ; Juvenile
Preparation: Ethanol
Locality: Monticello, Lawrence, Mississippi, United States, North America
  • Paratype: Webb, R. G. 1959. Univ. Kansas Publ., Mus. Nat. Hist. 11 (9).
Creative Commons Attribution 3.0 (CC BY 3.0)

© Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles

Source: National Museum of Natural History Collections

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Ecology

Habitat

Smooth softshell turtles are typically found along major riverine systems such as the Ohio, Missouri, and Mississippi rivers. They prefer large rivers and streams with medium to fast currents . Within river systems, smooth softshell turtles had highest populations in the open side channels and main channels of the Mississippi and Ohio Rivers in southern Illinois. Despite their preference for riverine systems, smooth softshell turtles have also been found in lakes, bogs, ponds, and drainage ditches. They generally prefer areas of sandy or mucky bottoms with little aquatic vegetation, and they avoid aquatic systems with a rocky substrate.

Smooth softshell turtles have microhabitat preferences within the Kansas River in Kansas. Males were observed more frequently than subadult and adult females in shallow depths along the river. Hatchlings also preferred shallow areas along the river, most likely to avoid larger aquatic predators.

Of the subspecies of smooth softshell turtles, Gulf coast smooth softshells (Apalone mutica calvata), have been found only in riverine and stream systems, while midland smooth softshells, (Apalone mutica mutica), have also been observed inhabiting lakes, bogs, drainage ditches, and ponds.

Range elevation: 1300 (high) m.

Habitat Regions: temperate ; freshwater

Aquatic Biomes: lakes and ponds; rivers and streams

Wetlands: marsh ; swamp ; bog

Other Habitat Features: riparian

  • Barko, V., J. Briggler. 2006. Midland smooth softshell (Apalone mutica) and spiny softshell (Apalone spinifera) turtles in the middle Mississippi River: Habitat associations, population structure, and implications for conservation. Chelonian Conservation and Biology, 5: 225-231.
  • Bodie, J., R. Semlitsch, R. Renken. 2000. Diversity and structure of turtle assemblages: Associations with wetland characters across floodplain landscape. Ecography, 23: 444-456.
  • Ernst, C., R. Barbour. 1972. Turtles of the United States. Lexington, Kentucky: University Press Kentucky.
  • Ernst, C., R. Barbour. 1989. Turtles of the World. Washington D.C.: Smithsonian Institution Press.
  • Plummer, M. 1977. Activity, habitat, and population structure in the turtle, Trionyx muticus. Copeia, 3: 431-440.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© The Regents of the University of Michigan and its licensors

Source: Animal Diversity Web

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Habitat and Ecology

Habitat and Ecology
Apalone mutica typically occur in medium-sized to large rivers with moderate to fast currents, but also occur in standing water bodies like lakes, ponds and marshes as long as these are connected to the river at least during floods. Soft bottoms are preferred, and accessible sandbanks must be present. Smooth Softshells are preferentially carnivorous omnivores, feeding mainly on insects but also taking other kinds of animal food as well as plant seeds and fruits.

Males reach 27 cm carapace length (CL); females 36 cm CL. Maturity is reached at four years in males, nine years in females; size at maturity is apparently unknown. Longevity probably exceeds 20 years. Generation time has not been calculated.

Females produce two to three clutches of about 14 (1–33) eggs. Incubation takes about 63 (44–82) days. Hatchlings measure 30–37 mm (reviews by Moler 2006, Ernst and Lovich 2009).

Systems
  • Terrestrial
  • Freshwater
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Comments: Large rivers and streams; in some areas also found in lakes, impoundments, and shallow bogs (Ernst and Barbour 1972). Usually in water with sandy or mud bottom and few aquatic plants. Often basks on sand bars and mudflats at edge of water. Eggs are laid in nests dug in high open sandbars and banks close to water, usually within 90 m of water (Fitch and Plummer 1975).

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Migration

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

In a Kansas river (Plummer and Shirer 1975), individual smooth softshells moved 2-4 km upstream or downstream in one day, and they were often recaptured in areas extending 2-3 river km. An adult female moved 7.8 km upstream in two days. Only one long-distance movement exceeded 8 km. Mean short-term home range length was 1.2 km (range up to about 2.4 km in adult females, 0.5 km (up to about 1.1 km) in males, but both sexes made long but brief movements out of their home ranges, and sometimes they shifted home range location during a single season.

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Trophic Strategy

Smooth softshell turtles are carnivorous, eating a variety of organisms including fish, amphibians (adults and larvae), arthropods, spiders (Araneae), snails (Campeloma), mollusks, isopods (Isopoda), millipedes (Diplopoda), and worms (Annelida). Although A. mutica is a dietary generalist, it can be classified as an insectivore. Arthropods typically consumed by smooth softshell turtles are aquatic and larval forms of Coleoptera, Diptera, Calliphoridae, Chironomidae, Cyclorrhapha, Empidae, Muscidae, Ephemeroptera, Tipulidae (Tipulo bicornis), Hemiptera, Hymenoptera, Homoptera, Isoptera, Lepidoptera, Ichneumonidae, Odonata, Neuroptera, Orthoptera, Plecoptera, and Trichoptera. Fish species consumed by smooth softshell turtles include Castostomus commersoni, Cyprinella whipplei, Cyprinella spiloptera, Lepomis macrochirus, Morone chrysops, Hypentilium nigricans, Perca flavescens, and Salvelinus fontinalis. Although primarily carnivorous, smooth softshell turtles occasionally eat vegetation such as algae, potatoes, seeds, stems, mulberry (Morus), fruits, and hard nuts.

Smooth softshell turtles hunt on both land and in water. They are ambush predators; while concealed in substrate, they use their long neck to grab passing prey. They have also been observed pharyngeal gulping, in which they suck in nearby small prey organisms. They also use their nose to seek food in sediment and vegetation. Females generally utilize deeper water to obtain food, while males tend to forage in shallow water near the shore. Although foraging area differs between sexes, food size does not vary with size or sex.

Animal Foods: birds; mammals; amphibians; fish; carrion ; insects; terrestrial non-insect arthropods; mollusks; terrestrial worms; aquatic crustaceans

Plant Foods: leaves; roots and tubers; wood, bark, or stems; seeds, grains, and nuts; fruit; algae

Primary Diet: carnivore (Insectivore )

  • Plummer, M., D. Farrar. 1981. Sexual dietary differences in a population of Trionyx muticus. Journal of Herpetology, 15: 175-179.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© The Regents of the University of Michigan and its licensors

Source: Animal Diversity Web

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Comments: Eats insects, crayfish, snails, worms, fish, and amphibians; males forage more along shore than do females (Collins 1982). Also reported to eat fruits and cottonwood seeds.

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Associations

Smooth softshell turtles are aquatic predators and fall prey to a variety of organisms. Eggs of this speices are parasitized by fly larvae (Sarcophagidae).

Commensal/Parasitic Species:

  • fly larvae Sarcophagidae

Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© The Regents of the University of Michigan and its licensors

Source: Animal Diversity Web

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Due to their high agility on land and water and these avoidance strategies, adults have few natural predators. Humans and alligators are the main predator of adults. Predators of hatchlings include fish, other turtles (common snapping turtles, alligator snapping turtles, possibly adult Apalone), water snakes, shoreline birds, bald eagles, and other mammals. Nest predation is usually from raccoons, skunks (Memphitis and Spilogale), crows, fire ants (Solenopsis invicta), fly larvae (Sarcophagidae), dogs, red foxes, moles (eastern moles, and other small mammals.

Smooth softshell turtles are wary and abandon their basking place if danger is perceived. They are highly agile, both in water and on land, which permits quick escape from predators. They also use their strong diving ability to flee predators and conceal themselves in mud. When caught by predators, a smooth softshell turtle pulls itself into its shell.

Known Predators:

  • raccoons (Procyon lotor)
  • common snapping turtles (Chelydra serpentina)
  • striped skunks (Memphitis memphitis)
  • crows (Corvus ossifragus)
  • fire ants (Solenopsis invicta)
  • red foxes (Vulpes vulpes)
  • fly larvae (Sarcophagidae)
  • moles (Scalopus aquaticus)
  • domestic dogs (Canis familiaris)
  • bald eagles (Haliaeetus leucocephalus)
  • water snakes (Nerodia)
  • alligator snapping turtles (Macrochelys temmincki)
  • humans (Homo sapiens)
  • alligators (Alligator mississippiensis)

  • Fitch, H., M. Plummer. 1975. A preliminary ecological study of the soft-shelled turtle Trionyx muticus in the Kansas River. Israel Journal of Zoology, 24: 28-32.
  • Watermolen, D. 2004. Softshell turtles (g. Apalone) as bald eagle prey. Bulletin of Chicago Herpetological Society, 39: 69-70.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© The Regents of the University of Michigan and its licensors

Source: Animal Diversity Web

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

General Ecology

Along the Kansas River in Kansas, Plummer (1977) estimated population density to be 1,900 individuals per 1.5 km of river (based on study of a major sandbar of that length); however, this estimate was influenced by temporary emigration and immigration from areas upstream and downstream; over the entire 14-km study area, Plummer made approximately 3,700 captures of 2,700 turtles; at least two-thirds of the population consisted of adults. Nest survivorship in Kansas was 0.43 (Fitch and Plummer 1975).

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Life History and Behavior

Behavior

Smooth softshell turtles primarily interact through visual and tactile cues. When seeking out mates, males physically investigate females. Although little information was found regarding perception and communication by this species, a close relative, spiny softshell turtles (Apalone spinifera), perceives its environment using chemical, visual, and tactile cues, vibrations and communicates using tactile cues.

Communication Channels: tactile

Perception Channels: visual ; tactile ; vibrations ; chemical

Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© The Regents of the University of Michigan and its licensors

Source: Animal Diversity Web

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Cyclicity

Comments: Active from April to October in ne. Kansas (Collins 1982).

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Life Cycle

Embyonic development of smooth softshell turtles is categorized into three stages: division of cells and tissue development, organogenesis, and the growth of the embryo before the hatching stage. The timing of these three stages is related to three equal corresponding periods during incubation. Sex determination is not temperature dependent, and relatively equal proportions of hatchlings are male and female.

With time, the round shape of a hatchling smooth softshell turtle's carapace changes to an oval shape through allometric growth. There is no change, however, in plastron shape as the hatchling grows, making for little change in the straight carapace length/plastron length (SCL/PL) ratio. Once the plastron has reached a minimum length of 60 mm, individuals can be sexed using physical characteristics described above. Unlike many other species of turtles, smooth softshell turtles do not form growth annuli on their shells, making them difficult to age in the field.

Growth of smooth softsell turtles typically occurs from May to September, and growth rates are usually highest from June to August. Males grow on average 1.95 mm/month when between lengths of 61 and 65 mm. At a plastron length (PL) of 66 to 75 mm, males grow at a rate of 2.1 to 2.5 mm/month. This rate decreases to 0.09 mm/month when males reach a PL of 111 to 115 mm. Females exhibit a faster growth rate than males. In females with a PL of 61 to 70 mm, growth rate is 2.8 mm/month. This decreases to 0.7 mm/month at a PL of 151 to 160 mm. Most species of turtles experience indeterminate growth, although this has not verified for this species.

Development - Life Cycle: indeterminate growth

  • Browne, C., S. Hecnar. 2007. Species loss and shifting population structure of freshwater turtles despite habitat protection. Biological Conservation, 138: 421-429.
  • Ewert, M. 1985. Embryology of turtles. Pp. 75-268 in C Gans, F Billett, P Maderson, eds. Biology of the Reptilia, Vol. 14. New York, New York: John Wiley and Sons.
  • Nagle, R., M. Plummer, J. Congdon, R. Fischer. 2003. Parental investment, embryo growth, and hatchling lipid reserves in softshell turtles (Apalone mutica) from Arkansas. Herpetologica, 59: 145-154.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© The Regents of the University of Michigan and its licensors

Source: Animal Diversity Web

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Life Expectancy

Unlike many other species of turtles, smooth softshell turtles do not form growth annuli on their shells, which makes them very difficult to age in the field. The lifespan of this species is unrecorded. Individuals in captivity have lived over 11 years, and they are believed to be capable of living 20 years. Florida softshell turtles (Apalone ferox) and spiny softshell turtles (Apalone spinifera) can live up to 25 years in captivity.

Average lifespan

Status: captivity:
11 years.

  • Snider, A., J. Bowler. 1992. Longevity of Reptiles and Amphibians in North American Collections. Pp. 1-44 in J Collins, ed. Herpetological Circular, Vol. 21. Utah: Society for the Study of Amphibians and Reptiles.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© The Regents of the University of Michigan and its licensors

Source: Animal Diversity Web

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Lifespan, longevity, and ageing

Observations: In captivity animals may live up to 11 years. Still, longevity in the wild should be higher and some animals are estimated to live over 20 years (http://www.pwrc.usgs.gov/neparc/).
Creative Commons Attribution 3.0 (CC BY 3.0)

© Joao Pedro de Magalhaes

Source: AnAge

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Reproduction

Breeding activity of smooth softshell turtles occurs from April to June and possibly into September. Males seek out females by approaching other adults. If the approached individual is male, the response to the investigation is usually passive but can be aggressive on occasion. Non-receptive females are often aggressive; during the breeding season many males are observed with wounds inflicted by females. Receptive females, on the other hand, are passive to the advances of a male. Many males may be present near a receptive female, and all may attempt to mate with her. When there is only one male present, the female may chase the male.

Copulation almost always occurs in the water, and a sexually receptive female is mounted from behind. Deep water is usually needed to successfully mount a female and a male must swim in place for upwards of 20 min to keep his position. During this time, the male needs to keep its vents aligned.

Mating System: polygynous

Smooth softshell turtles nest between late May and July. In more northern locations such as Minnesota and Wisconsin, nesting typically takes place from June to early July. Any disturbance can cause early abandonment of the nest by wary females. Females dig a nest cavity 15 to 30 cm deep with their hind feet. Nests are typically located on a sand bar with little vegetation, although some nests have been found in dense vegetation. Nests are generally located within 18 m of the water and only rarely are more than 30 m away from water. Nests are usually 0.5 to 6.1 m above the water. Nest density can be quite high, and in some cases there are connecting chambers between nests. Oviposition usually occurs in the early morning. Eggs are laid in two layers in the nesting chamber. Females cover their eggs with sand using their hind feet. A female then usually burrows a tunnel and places herself on the opposite end of the nest. This tunnel can be up to 4 m in length.

Female smooth softshell turtles lay only one clutch per year. Average clutch size is 15 to 25 eggs. The minimum observed clutch size is 1 egg while the maximum clutch size observed is 33 eggs. Clutches laid later in the season are usually smaller in size than early season clutches. The size of a clutch is proportional to the straight carapace length (SCL) of the female. Eggs are a spheroidal shape and resemble ping-pong balls. In a typical clutch, 75% of eggs are likely to survive. Predation and flooding can have large effects on egg survival.

Eggs generally hatch in 8 to 12 weeks. Hatching frequency is highest in August to September. Hatchlings use their front claws to break through the egg, relying on their claws more than their caruncle (egg tooth), which is less used in comparison to other species. Hatchlings generally emerge from the nest around sunset. At the moment of hatching, hatchlings are completely independent. Recently hatched smooth softshell turtles average 4 cm in straight carapace length and have a body mass of 3.0 to 7.5 g (mean 5.4 g). Caruncles drop off in a week, and the umbilical scar is usually 2 mm in diameter.

Male smooth softshell turtles become sexually mature during their fourth year with mean plastron length (PL) ranging from 80 to 85 mm. Females become sexually mature during their ninth year with mean PL ranging from 140 to 150 mm. Mature individuals attempt to mate immediately upon emergence from hibernation. The volume of mature male testes varies with season, with testes reaching a maximum diameter immediately before hibernation. In April and May, the vas deferens of males become swollen, 2 mm in diameter. The vas deferens is no longer swollen by June but become swollen with sperm once more by October. Vitellogenesis in females begins in July in Kansas.

Breeding interval: Female smooth softshell turtles have one clutch per year.

Breeding season: In Minnesota, breeding occurs in May and June, and nesting occurs in June and July.

Range number of offspring: 1 to 33.

Average number of offspring: 15 to 25.

Range gestation period: 8 to 12 weeks.

Range age at sexual or reproductive maturity (female): 7 (low) years.

Average age at sexual or reproductive maturity (female): 9 years.

Average age at sexual or reproductive maturity (male): 4 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous

Smooth softshell turtles provide prenatal care for their offspring. Females produce high levels of non-polar lipids that provide energy for their growing embryos. They produce energy at a level much higher than what is necessary to keep the embryos alive, which is known as parental investment in embryogenesis. At birth, hatchlings have high concentrations of lipids. These act as a food source until they are mature enough to begin feeding. This allocation of energy into high storage reserves for hatchlings represents parental investment in care. This provisioning of lipids enables hatchlings to survive in areas that have low resource availability.

Parental Investment: pre-hatching/birth (Provisioning: Female)

  • 2009. "Smooth softshell (Apalone mutica)" (On-line). Wisconsin Department of Natural Resources. Accessed April 15, 2011 at http://dnr.wi.gov/org/land/er/biodiversity/index.asp?mode=info&Grp=49&SpecCode=ARAAG01020.
  • Doody, J. 1996. Summers with softshells. Bulletin of Chicago Herpetological Society, 31: 132-133.
  • Ernst, C., J. Lovich. 2009. Turtles of the United States and Canada. Baltimore, Maryland: The John Hopkins University Press.
  • Ernst, C., R. Barbour. 1972. Turtles of the United States. Lexington, Kentucky: University Press Kentucky.
  • Nagle, R., M. Plummer, J. Congdon, R. Fischer. 2003. Parental investment, embryo growth, and hatchling lipid reserves in softshell turtles (Apalone mutica) from Arkansas. Herpetologica, 59: 145-154.
  • Oldfield, B., J. Moriarty. 1994. Amphibians & Reptiles Native to Minnesota. Minneapolis, Minnesota: University of Minnesota Press.
  • Plummer, M. 1976. Some aspects of nesting success in the turtle, Trionyx muticus. Herpetologica, 32: 353-359.
  • Plummer, M. 1977. Activity, habitat, and population structure in the turtle, Trionyx muticus. Copeia, 3: 431-440.
  • Plummer, M., H. Shirer. 1975. Movement patterns in a river population of the softshell turtle Trionyx muticus. University of Kansas Museum of Natural History Occasional Papers, 43: 1-26.
  • Vogt, R. 1981. Natural History of Amphibians and Reptiles of Wisconsin. Wisconsin: Milwaukee Public Museum.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© The Regents of the University of Michigan and its licensors

Source: Animal Diversity Web

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Lays 1-3 clutches of 4-33 eggs, May to July. Eggs hatch in 2 to 2.5 months. Females sexually mature in about 6-9 years, males in 4 years (Collins 1982).

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Conservation

Conservation Status

Although smooth softshell turtles are listed as a speices of least concern by the IUCN, little data is available to make a confident assessment. Currently, this species is widespread and locally common, suitable habitat is present, and harvest rates do not contribute to decline. Smooth softshell turtles are listed as a species of special concern in the state of Minnesota. Their slow maturation rate increases time necessary to restore populations.

Their ability to absorb oxygen from the water has made smooth softshell turtles susceptible to water pollution. Other negative impacts include habitat degradation, harvesting for food, changes in hydrological regimes (construction of dams and locks), and an increase in human disturbances at nesting sites. Human disturbance includes boating near nest sites, with waves resulting from boat use causing erosion and egg exposure. This species is also caught as bycatch (capture of non-target species) in the commercial fishing industry.

Efforts to conserve smooth softshell turtle should include the protection of waterways and surrounding terrestrial land that are known to support large populations of this species. Upstream sites should also be protected. Protected areas ideally should include basking and nesting habitats with high densities of prey, hibernation areas, and be of ample size to support home ranges.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: no special status

  • Moll, E., D. Moll. 2000. Conservation of river turtles. Pp. 126-155 in M Klemens, ed. Turtle Conservation. Washington D.C.: Smithsonian Institution Press.
  • Pappas, M., J. Congdon, A. Pappas. 2001. Weaver Bottoms 2001 turtle survey: management and conservation concerns. Nongame Wildlife Survey, Minnesota Department of Natural Resources and U.S. Fish and Wildlife Service.
  • Trauth, S., H. Robison, M. Plummer. 2004. The amphibians and Reptiles of Arkansas. Fayetville: University of Arkansas Press.
  • van Dijk, P. 2010. "Apalone mutica" (On-line). In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.1. Accessed July 05, 2011 at http://www.iucnredlist.org/apps/redlist/details/165596/0.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© The Regents of the University of Michigan and its licensors

Source: Animal Diversity Web

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2013

Assessor/s
van Dijk, P.P.

Reviewer/s

Contributor/s

Justification
Apalone mutica is a reasonably widespread, fairly cryptic, and locally common species with high reproductive potential by turtle standards. Extensive areas of suitable habitat exist and are likely to remain for the foreseeable future. Harvest rates appear not significant enough to have led to documented localised declines. Nevertheless, this assessment is more an issue of lack of data documenting a decline than available data indicating stable populations; population monitoring is highly desirable as the species can be argued to warrant Near Threatened. It is however currently listed as Least Concern.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

National NatureServe Conservation Status

United States

Rounded National Status Rank: N5 - Secure

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

NatureServe Conservation Status

Rounded Global Status Rank: G5 - Secure

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Population

Population
Apalone mutica can reach substantial densities, up to 1.2 individuals per linear meter of river, and a basking aggregation of 88 animals was reported (Plummer 1977, Trauth et al. 2004). However, there have been anecdotal observations of declining populations, at least locally, as well as consistently failing recruitment as a result of water level regulation in large rivers flooding nesting banks (Janzen pers. comm. 2010).

Population Trend
Unknown
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Threats

Major Threats
The impact of commercial exploitation appears undocumented and unquantified, though bycatch in commercial fisheries and recreational fishing has been suspected to be a factor in the observed decline in at least some populations (Janzen pers. comm. 2010).

Water pollution has been implicated in population reductions (Trauth et al. 2004). Increasingly frequent flooding events, resulting from a combination of anthropogenic activities upstream (increased hard surface area, increased stormwater runoff volumes and speed) and changing, more pulsed, precipitation patterns, consistently impact nesting areas and may preclude successful reproduction (e.g., Cedar River, Iowa) (Janzen pers. comm. 2010).
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Management

Conservation Actions

Conservation Actions
Apalone mutica is subject to a variety of State legislation and regulations, and likely occurs in several protected areas.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Relevance to Humans and Ecosystems

Benefits

Although smooth softshell turtles may prey upon game fish, their impact on fish populations is believed to be insignificant. There are no known adverse effects of smooth softshell turtles on humans, although they may bite when handled.

Negative Impacts: injures humans (bites or stings)

Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© The Regents of the University of Michigan and its licensors

Source: Animal Diversity Web

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

In some regions, adults and eggs are gathered for food. Additionally, this species is occasionally a part of the pet trade.

Positive Impacts: pet trade ; food

Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© The Regents of the University of Michigan and its licensors

Source: Animal Diversity Web

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Wikipedia

Smooth softshell turtle

The smooth softshell turtle (Apalone mutica) is a softshell turtle of the family Trionychidae. It is endemic to North America.

Geographic range[edit]

It lives mainly in the Mississippi River drainage, including the Ohio River and the lower Allegheny River.

Description[edit]

The smooth softshell turtle is usually brown or olive-colored, often with darker dots or dashes. It is the only softshell without ridges in the nostrils. Females are 18-35.6 cm (7-14 inches); males, 12.5-17.8 cm (5-7 inches).

Reproduction[edit]

From May to July, the females lay bunches of three to 28 eggs about 100 m from water in sandy areas.[4]

Sympatric species[edit]

Apalone mutica is sympatric with the spiny softsl turtle (Apalone spinifera) over much of its range.[5]

References[edit]

  1. ^ Tortoise & Freshwater Turtle Specialist Group (1996). Apalone mutica. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2.
  2. ^ ITIS.gov
  3. ^ Fritz Uwe; Peter Havaš (2007). "Checklist of Chelonians of the World". Vertebrate Zoology 57 (2): 306. ISSN 18640-5755. Archived from the original on 2010-12-17. Retrieved 29 May 2012. 
  4. ^ DNr.wi.gov
  5. ^ JSTOR.org
Creative Commons Attribution Share Alike 3.0 (CC BY-SA 3.0)

Source: Wikipedia

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Names and Taxonomy

Taxonomy

Comments: Removed from genus Trionyx and placed in genus Apalone by Meylan (1987). North American softshell turtles were retained in Trionyx by Webb (1990) and Ernst et al. (1994).

Molecular data indicate a genetic dichotomy between populations north and west of Louisiana and populations from the Gulf Coast in southeastern North America (Weisrock and Janzen 2000).

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Disclaimer

EOL content is automatically assembled from many different content providers. As a result, from time to time you may find pages on EOL that are confusing.

To request an improvement, please leave a comment on the page. Thank you!