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Pseudemys suwanniensisSuwannee River Cooter

By Alyssa Dean

Geographic Range

Suwannee River cooters (Pseudemys suwanniensis) are endemic to the western part of the peninsula of Florida and their range mainly consists of the following counties: Alachua, Gilchrist, Dixie, and Taylor County to Hillsborough County. Suwannee River cooters can be found in the Suwannee River and any other bodies of water flowing into the Gulf of Mexico that are located in the western part of the Florida peninsula. Recent studies also show that they can be found farther north in the Suwannee watershed. These cooters can also be found as far west as the Ochlockonee River in the Panhandle. ("Atlas of Amphibians and Reptiles of Florida", 2011; Ernst and Lovich, 2009; Wilson, 1995)

Habitat

Suwannee cooters inhabit rivers, marshes, ponds, swamps, wetlands, and bays on the Gulf coast. These cooters are found in darker (tannic) waters, clear water, and they are tolerant of brackish waters. They are commonly found in bodies of water that have an abundant source of aquatic vegetation, slow to moderate currents, and sandy bottoms. While in the water, these turtles spend most of their time resting on the bottom or foraging. They spend 30 seconds to 4 minutes at the surface to catch their breath before diving back down. They typically dive 1.0 to 1.5 m. When they are not in the water, they bask in the sun on logs.

When females are making nests, they typically travel within 30 m from the water's edge, but can travel up to 250 m to nest. When female Suwannee cooters travel to find a place to nest, they look for areas that have soft soil. They also nest in raised areas near the water so that hatchlings do not have to travel far to reach water. Adults and juveniles live in the same microhabitats. (Conant and Collins, 1998; Ernst and Lovich, 2009; Wilson, 1995)

  • Range elevation
    0 (low) m
    0.00 (low) ft
  • Range depth
    1.5 to 1.0 m
    4.92 to 3.28 ft

Physical Description

Adult Suwannee cooters have elongated, oval-shaped carapaces. The middle of the carapace is the highest point, and the posterior side is serrated. The carapaces of Suwannee cooters usually appear black or olive brown with markings that are a cream to yellow color. Their cervical scutes are very small compared to their dorsal length and it covers less than 35% of their total length. The second pleural scute has a light colored marking that is present in the shape of a backwards C. Their heads are also an olive brown or black color with very thin greenish-yellow to white stripes as well as some on their limbs. Suwannee River cooters usually have yellow or orange plastrons. Their tails are long and thick with an anal vent behind their carapacial rim.

The average mass of adult Suwannee River cooters is 10 kg. Females grow to be 27 to 30 cm in length. Males are smaller - 17 to 20 cm in length - and more flattened than females. Female Suwannee River cooters have long front claws; males start with long claws, but they wear down due to mating efforts.

The carapaces of hatchling Suwannee cooters has dark grey blotches on a pale grey background. These blotches fade within a few days of hatching and their adult colors are more evident. Juveniles also have vertebral keels that disappear with age. At hatching, they are 27 to 43.2 mm long (averaging 36.6 mm) and weigh 10.2 to 14.0 g (averaging 11.6 g). (Conant and Collins, 1998; Ernst and Lovich, 2009; Seidel and Dreslik, 1996; Wilson, 1995)

  • Sexual Dimorphism
  • female larger
  • sexes shaped differently
  • Average mass
    10 kg
    22.03 lb
  • Range length
    17 to 30 cm
    6.69 to 11.81 in

Development

Suwannee River cooters start off as an egg, which are 29.5 to 46.0 mm long and 22.7 to 30.6 mm wide. Egg masses range from 9.79 to 21.65 grams. These eggs hatch 58 to 122 days (average of 86 days) after being laid. Sex determination depends on the temperature of their surroundings, which normally ranges from 25 to 33°C. Eggs located in shaded areas ranging from 25 to 28°C produced males, while eggs in higher temperatures ranging from 29 to 32°C produced females.

Some hatchlings will emerge after hatching but others might stay in their nests over the winter and emerge the next spring. When hatchlings emerge they are pale grey with dark grey patches. A few days after they hatch, their dark grey patches start to turn a brownish-green color separated by a network of yellowish-green patterns. Hatchlings have yellowish-green plastrons with grayish-brown markings along the network of their plastrons. Juveniles tend to have a vertebral keel, which disappears as they grow. As they reach adulthood their colors and patterns become more distinct.

These turtles have slow average growth rates of up to 5 mm per year and about 11 mm every three years until they reach sexual maturity. Males grow slower after they reach about 20 cm in plastron length while females have slower growth rates after they reach 27.5 to 30 cm in plastron length. Like all turtles, growth is indeterminate. (Conant and Collins, 1998; Ernst and Lovich, 2009; Jackson and Walker, 1997)

Reproduction

Mating occurs from January into June. Male Suwannee River cooters find females and will swim with their snouts close to the tails of females. This suggests that males follow pheromones released by females. While pursuing females, males extend their head and neck over the females. Then male Suwannee River cooters position their front claws to the side and anterior of the snouts of females. Males then vibrate their claws to stimulate females. If females are receptive, they will sink to the bottom and allow males to slide backwards to mount. If female cooters are not receptive, they either try to outswim males or swim under a submerged object (like a rock or log) so males cannot mount.

Suwannee River cooters are promiscuous, which means both males and females have multiple mates throughout the breeding season. After mating, female Suwannee River cooters start nesting. Females will dig the nest and make three different holes but will only lay eggs in one hole; the other two are false nests. (Ernst and Lovich, 2009; Wilson, 1995)

Suwannee River cooters are iteroparous, which means they nest each year. Their breeding season goes from Jaunary to June and egg-laying occurs from May to July. Between these few months, female Suwannee cooters may lay six to seven clutches, but on average they lay three clutches of eggs every 21.4 days. Each clutch may have 2 to 27 eggs, with an average of 16.4 ± 5.4 eggs. Across all clutches laid per year, females may lay between 70 and 100 eggs.

Once their eggs are laid, they are independent of their mothers. Each egg weighs 6.8 to 22.4 g with an average weight of 16.3 g. Eggs incubate for 58 to 122 days with a mean of 86 days before they hatch.

Male Suwannee River cooters reach sexual maturity between 8 to 10 years old, while females reach sexual maturity from 9 to 13 years old. (Ernst and Lovich, 2009; Jackson and Walker, 1997; Wilson, 1995)

  • Breeding interval
    They breed multiple times during the mating system
  • Breeding season
    January through July
  • Range number of offspring
    2 to 27
  • Range gestation period
    58 to 122 days
  • Average gestation period
    86 days
  • Average time to independence
    0 minutes
  • Range age at sexual or reproductive maturity (female)
    9 to 13 years
  • Range age at sexual or reproductive maturity (male)
    8 to 10 years

Once female Suwannee River cooters find a place with soft soil on a raised area near the water, they dig a nest with their hind feet. Females make their nests with three holes. They lay their eggs in one main nest while the other two holes are used to fool predators. In the two false nests, females may lay 1 to 4 eggs that draw predators away from the main nest. After laying their eggs, females cover up the nest holes and return to the water. Adult female Suwannee River cooters do not show any parental investment beyond these actions. Males do not show any parental investment beyond the act of mating. (Ernst and Lovich, 2009)

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

Lifespan/Longevity

Slevins and Slevins (2003) reported that one male Suwannee River cooter was caught as a juvenile and survived in captivity for 40 years, 8 months, and 4 days. The age of the male was unknown beyond its juvenile grouping. Researchers of wild populations of Suwannee River cooters reported that once females reach maturity (between 10 to 15 years) they will live another 20 to 25 years or more in the wild. There are no other reports about the lifespan of Suwannee River cooters, but it can be expected that they live between 20 and 40 years. This estimate is based on reports of river cooters (Pseudemys concinna) and Coastal plain cooters (Pseudemys concinna floridana). (Ernst and Lovich, 2009; Slevins and Slevins, 2003)

  • Range lifespan
    Status: captivity
    40.75 (low) years
  • Typical lifespan
    Status: wild
    30 to 40 years

Behavior

Suwannee River cooters are active throughout the year. In winter, they restrict most of their activity to warm sunny days. Most of their activity occurs throughout the day, except during nesting season when some females finish nesting and laying their eggs at night.

They spend their time foraging at dusk and dawn. Throughout the day they spend their time basking on the waters edge or on logs. While foraging, they travel up and down the river. When they are not basking, these turtles spend most of their time underwater (1.0 to 1.5 m below the surface). They come to the surface and poke their heads out of the water to breathe for about 30 seconds to 4 minutes and then return to the bottom. After they breathe they return to the bottom of their body of water and lay there with their eyes closed for a few minutes up to 3 hours. On average, they remain submerged for about an hour. They are not social and spend their time alone except during breeding season, or if they are sharing a suitable basking site. During their breeding season, females and males communicate using pheromones. Females travel along the riverbank or on nearby land to find a nesting place for their eggs. (Ernst and Lovich, 2009)

Home Range

Suwannee River cooters do not go on land unless they are basking or nesting. When spending most of their time in water, they travel linear distances of 640 m or more. They travel 200 to 343 m per day. Some females may travel outside of their home range in search of a suitable place to nest, but will return to their home range after they are done. (Ernst and Lovich, 2009)

Communication and Perception

Suwannee cooters spend most of their time by themselves, but they do tend to share favored basking sites. They typically communicate using pheromones during the breeding season. When females are ready to breed, they release pheromones that males can smell and follow even if they cannot yet see the female releasing its pheromones. When pursuing each other, the pairs bump their snouts together before deciding if they are ready to mate. When breeding, males use tactile and visual communication, positioning themselves so that their plastrons rest on the carapaces of females. When on top, males vibrate their foreclaws in front of females to attract them.

Females use visual and tactile clues to select suitable nesting sites. Both sexes use visual and tactile cues (and likely chemical cues in the water) to forage efficiently. (Ernst and Lovich, 2009)

Food Habits

Juvenile Suwannee cooters are omnivores, consuming small fish, snails, insects, and occasionally plant materials. As they develop into adults, they switch to a strictly herbivorous diet. In freshwater habitats adults have diets consisting of aquatic mosses, algae, vascular plants, cyanobacteria, and diatoms. Suwannee cooters that are found in saltwater or brackish waters tend to eat mostly turtle grass (Thalassia testudinum) and occasionally carrion. Research has shown that the stomach contents of adult Suwannee River cooters contain different percentages of plants. In one study, the stomach contents included 82.3% guppy grass (Najas guadalupensis), 5.5% coontail (Ceratophyllum demersum), 2.5% strap-leaf sagittaria (Sagittaria kurziana), and 2.5% of filamentous algae. (Ernst and Lovich, 2009; Wilson, 1995)

  • Animal Foods
  • fish
  • carrion
  • mollusks
  • Plant Foods
  • leaves
  • bryophytes
  • algae
  • Other Foods
  • microbes

Predation

Adult Suwannee River cooters are preyed upon by humans (Homo sapiens) and American alligators (Alligator mississippiensis).

Juvenile Suwannee River cooters are preyed upon by herons (Family Ardeidae), common snapping turtles (Chelydra serpentina), alligator snapping turtles (Macrochelys temminckii), black bass (Micropterus), and crested caracaras (Caracara cheriway).

Nesting females may be attacked by raccoons (Procyon lotor) over their eggs. Other egg predators include red imported fire ants (Solenopsis victa), fish crows (Corvus ossifragus), turkey vultures (Cathartes aura), black vultures (Coragyps atratus), eastern moles (Scalopus aquaticus), striped skunks (Mephitis mephitis), Virginia opossums (Didelphis virginiana), and feral hogs (Sus scrofa).

When defending themselves, adult Suwannee cooters will usually hide in their shells and wait until predators have left. Some adults will kick and use their claws to scratch their attacker. Sometimes they will even urinate to repel predatorsa. They can, but typically do not bite their attackers. The colors and patterns of Suwannee River cooters help camouflage them in their natural habitat. (Ernst and Lovich, 2009)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Suwannee River cooters are omnivores and are preyed upon by a number of mammalian mesopredators, large wading birds, larger turtles, and fish. Suwannee River cooters impact their ecosystems by digging holes for their nests, allowing soil aeration to occur. Suwannee River cooters do not use any other species as hosts and do not share any mutuality with other species. Their ecosystems allow them to bask in the sun throughout most of the year, which is essential for Suwannee River cooters to shed their old scutes and grow. Basking also helps Suwannee cooters to absorb their food, eliminate the buildup of algae, and get rid of parasitic leeches (subclass Hirudinea). Particular parasites (beyond leeches) have not been reported. (Ernst and Lovich, 2009; Stunkard, 1924; Turner, et al., 2013)

Commensal/Parasitic Species
  • leeches (subclass Hirudinea)

Economic Importance for Humans: Positive

Humans benefit from Suwannee River cooters by capturing and consuming them. Suwannee River cooters are harvested for their meat or to keep as pets. In 2009, the Florida Fish and Wildlife Conservation Commission prohibited Suwannee River cooters from being harvested in Florida. People who had Suwannee River cooters before July 20, 2009 must have obtained a Class III Personal Pet License in order to keep their turtles and they are only allowed to own two. (Ernst and Lovich, 2009; Lechowiez, et al., 2011; Turner, et al., 2013)

Economic Importance for Humans: Negative

There are no negative economic impacts of Suwannee River cooters on humans. (Ernst and Lovich, 2009)

Conservation Status

Suwannee cooters are not listed on the IUCN Red List because taxonomic disagreements list them as a subspecies of river cooters (Pseudemys concinna). They have no special status on the US Federal List, CITES, and the State of Michigan List. Florida considers them a species of special concern.

Major threats facing Suwannee River cooters include river degradation, alterations to rivers (dredging, impoundment, snag removal, and siltation), and nest predation. Another major threat is human hunting practices. Humans take Suwannee River cooters from their natural environment for consumption and as pets (no longer legal in Florida). Humans also cause impacts from motorized boats and building developments across from waterways, increasing pollution. Increases in pollution levels causes shell disease in Suwannee River cooters.

In 2009, the Florida Fish and Wildlife Conservation Commission prohibited harvesting of Suwannee River cooters and other cooters that have similar appearances. People that owned Suwannee River cooters before July 20, 2009 are allowed to keep their turtles as long as they obtain a Class III Personal Pet License. The possession limit only allows people to own two turtles. (Ernst and Lovich, 2009; Turner, et al., 2013; van Dijk, 2011)

Contributors

Alyssa Dean (author), Radford University, Lauren Burroughs (editor), Radford University, Logan Platt (editor), Radford University, Karen Powers (editor), Radford University, Galen Burrell (editor), Special Projects.

Glossary

Nearctic

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.

World Map

bilateral symmetry

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.

brackish water

areas with salty water, usually in coastal marshes and estuaries.

carnivore

an animal that mainly eats meat

carrion

flesh of dead animals.

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

cryptic

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.

diurnal
  1. active during the day, 2. lasting for one day.
ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

estuarine

an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

freshwater

mainly lives in water that is not salty.

herbivore

An animal that eats mainly plants or parts of plants.

indeterminate growth

Animals with indeterminate growth continue to grow throughout their lives.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

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).

marsh

marshes are wetland areas often dominated by grasses and reeds.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

soil aeration

digs and breaks up soil so air and water can get in

solitary

lives alone

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

visual

uses sight to communicate

References

Florida Fish and Wildlife Conservation Commission. Atlas of Amphibians and Reptiles of Florida. Final Report, Project Agreement 08013. Tallahassee, Florida: Krysko, K.L., K.M. Enge, and P.E. Moler, Florida Fish and Wildlife Conservation Commission. 2011. Accessed February 17, 2020 at https://www.floridamuseum.ufl.edu/herpetology/florida-amphibians-reptiles/checklist-atlas/.

Aresco, M., J. Dobie. 2000. Variation in shell arching and sexual size dimorphism of river cooters, Pseudemys concinna, from two river systems in Alabama. Journal of Herpetology, 34/2: 313-317.

Conant, R., J. Collins. 1998. Reptiles and Amphibians Eastern/Central North America. New York, New York: Houghton Mifflin Company.

Dreslik, M. 1996. Ecology and Community Relationships of the River Cooter, Pseudemys concinna in a Southern Illinois Backwater (Master's Thesis). Charleston, Illinois: Eastern Illinois University.

Ernst, C., R. Barbour. 1989. Turtles of the World. Washington, D.C., and London: Smithsonian Institution Press.

Ernst, C., J. Lovich. 2009. Turtles of the United States and Canada, Second Edition. Baltimore, Maryland: The John Hopkins University Press.

Ewert, M. 1991. Egg Incubation: Its Effects on Embryonic Development in Birds and Reptiles. Cambridge, UK: The Press Syndicate of the Cambridge University Press.

Iverson, J. 2001. Reproduction of the river cooter, Pseudemys concinna, in Arkansas and across its range. The Southwestern Naturalist, 46/3: 364-370.

Jackson, D., R. Walker. 1997. Reproduction in the Suwannee River cooter, Pseudemys concinna suwanniensis. Bulletin of the Florida Museum of Natural History, 41/2: 69-167. Accessed March 24, 2020 at https://ufdc.ufl.edu/UF00095789/00001/1j.

Johnston, G., J. Mitchell, E. Suarez, T. Morris, G. Shemitz, P. Butt, R. Knight. 2016. The Santa Fe River in northern Florida: Effect of habitat heterogeneity on turtle populations. Bulletin of the Florida Museum of Natural History, 54/5: 69-103.

Kornilev, Y., C. Dodd Jr., G. Johnston. 2010. Linear home range, movement, and spatial disturbance of the Suwannee cooter (Pseudemys concinna suwanniensis) in Blackwater River. Chelonian Conservation and Biology, 9/2: 196-204.

Kornilev, Y. 2008. Behavioral Ecology and Effects of Disturbance on the Suwannee Cooter (Pseudemys concinna suwanniensis) in a Blackwater Spring-Fed River (Master's Thesis). Gainesville, Florida: University of Florida.

Lagueux, C., K. Bjorndal, A. Bolten, C. Campbell. 1995. Food habits of Pseudemys concinna suwanniensis in a Florida spring. Journal of Herpetology, 29/1: 122-126.

Lechowiez, C., P. Meylan, P. Moler, T. Thomas, W. Turner. 2011. Suwannee Cooter Biological Status Review Report. Tallahassee, FL: Florida Fish and Wildlife Conservation Commission.

Moll, M., E. Moll. 2004. The Ecology, Exploitation, and Conservation of River Turtles. New York City, New York: Oxford University Press.

Seidel, M., M. Dreslik. 1996. Reptilia: Testudines: Emydidae. Catalogue of American Amphibians and Reptiles, 626: 1-12.

Shemitz, G., J. Mitchell, G. Johnston, P. Butt. 2018. Origin and structure of a larger aggregation of Suwannee cooters (Pseudemys concinna suwanniensis) in a Florida spring. Chelonian Conservation and Biology, 17/1: 54-62.

Slevins, F., K. Slevins. 2003. "Reptiles and amphibians in captivity" (On-line). Longevity. Accessed April 30, 2020 at http://www.pondturtle.com/lturtle.html#Pseudemys.

Stunkard, H. 1924. On some trematodes from Florida turtles. Transactions of the American Microscopical Society, 43/2: 97-117.

Turner, W., D. Jackson, J. Williams. 2013. A Species Action Plan for the Suwannee Cooter (Pseudemys suwanniensis). Tallahassee, FL: Florida Fish and Wildlife Conservation Commission.

Wilson, L. 1995. The Land Manager's Guide to the Amphibians and Reptiles of the South. Chapel Hill, North Carolina: The Nature Conservancy, Southeastern Region.

van Dijk, P. 2011. "Pseudemys concinna (errata version published in 2016)" (On-line). The IUCN Red List of Threatened Species 2011: e.T163444A97425355. Accessed April 19, 2020 at https://dx.doi.org/10.2305/IUCN.UK.2011-1.RLTS.T163444A5606651.en.

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