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Sternotherus odoratusCommon Musk Turtle, Stinkpot Turtle

By Katelyn Lowery

Geographic Range

Common musk turtles (Sternotherus odoratus), also called stinkpots, are found throughout the eastern and central United States, with the exception of higher elevations areas such as the Blue Ridge Mountains. Their geographic range extends as far north as parts of south Maine, Michigan, and Wisconsin, as well as parts of south Ontario, Canada. Their range includes the East Coast, as far south as south Florida. Their range continues along the Gulf Coast and the western bounds of their range include east Texas, east Oklahoma, southeast Kansas, south-central Arkansas, and Illinois. (Buhlmann, et al., 2008; Ernst, 1986; Mitchell, 1994)

Habitat

Stinkpots seldom stray far from water, except for females when they are laying eggs. Stinkpots are most often found in permanent wetlands such as ponds, lakes, or human-made impoundments where aquatic plants can provide sufficient food. They are also found frequently in streams, rivers, and swamps. They typically rest in shaded areas that are low enough for their carapaces to touch the ground. Most of their time is spent on the bottom of bodies of water, searching for mates or for prey in the sediment, giving them the nickname "bottom walker".

Stinkpots are known to return to the sites where they were born when they are displaced. Stinkpots tend to be more active in new areas compared to their natal areas. Males move more than females, on average, likely in an attempt to mate with multiple females. Stinkpots have been observed basking in trees up to 2 m above water. They are found more frequently in shallow water, and are rarely discovered at depths greater than 2 m.

The highest elevation for a known population of stinkpots is 1,170 m in Lake Ravenel of Macon County, NC. (Andres and Chambers, 2006; "Assessment and Status Report on the Stinkpot", 2002; Buhlmann, et al., 2008; Heiss, et al., 2010; Klemens, 2000; Lindeman, 2013; Mitchell, 1994; Palmer and Braswell, 1995; Rowe, et al., 2009; Wilson, 1995)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • Range elevation
    1,170 (high) m
    ft
  • Range depth
    2 (high) m
    6.56 (high) ft

Physical Description

Stinkpots have brown carapaces with small, yellow plastrons. Their carapaces are elongated, narrow, and rounded with irregular patterns of black streaks or spots. Their skin is typically greyish-black, with multiple patterns of yellow spots and streaks on their legs and lower necks. Stinkpots have a pair of dark or pale yellow stripes on each side of their heads: one above and one below each eye. These facial stripes distinguish stinkpots from other species in the genus (Sternotherus). They have white or yellow skin, which is visible between the seams of their plastrons. Their plastrons have a single, nonfunctional hinge. Stinkpots also have elongated, pointed snouts and have barbels on their chins and necks. For some individuals, these barbels are reduced in size. It is common for algae to grow on parts or all of their shells.

Males have larger tails and heads compared to females. Males also have differently shaped tails, which go from wide at the base to very thin at the end. The average length for adults is between 100 to 127 mm. Average adult body mass is 100 g.

Stinkpot hatchlings are the smallest turtles in North America, with an average carapace length of 25 mm and a weight range of 1.6 to 3.2 g. Hatchlings resemble adults with the exception of their carapaces, which have noticeably higher midline keels compared to adults. Adults also have noticeable midline keels, but they are much smaller than the keels of hatchlings. The yellow head stripes of juveniles are more distinct compared to adults.

Stinkpots are often mistaken for striped mud turtles (Kinosternon baurii) and eastern mud turtles (Kinosternon subrubrum), especially since all three species have overlapping ranges. However, stinkpots are distinguishable by the presence of skin visible between the scutes of their plastrons. The other two species also have two hinges on their plastrons and their carapaces are never keeled (Buhlmann, et al., 2008; Jackson, 2011; Mitchell, 1994; Reynolds and Seidel, 1983)

  • Sexual Dimorphism
  • male larger
  • sexes shaped differently
  • Average mass
    100 g
    3.52 oz
  • Range length
    100 to 127 mm
    3.94 to 5.00 in
  • Average length
    111 mm
    4.37 in

Development

Stinkpot eggs are thick, but brittle-shelled. On average, eggs are 1.9 cm wide by 2.5 cm long. As female size and clutch size increase, egg width increases and egg length decreases. Yolk development occurs between August and December, and takes place in the ovarian follicles of females. Egg yolk ranges in diameter from 14.7 to 16.8 mm. Stinkpots exhibit indeterminate growth, meaning they do not cease growing throughout their lifetime. However, growth rates are fastest for hatchlings and juveniles, and slower after stinkpots reach adulthood.

Female stinkpots lay 1 to 4 clutches of eggs per season, with a total of 1 to 6 eggs per clutch. Females excavate burrows where they lay their eggs, which typically incubate for 65 to 86 days. Stinkpots exhibit temperature-dependent sex determination. At temperatures greater than 28 °C, nearly all eggs develop into females, whereas temperatures below 25 °C produce nearly all males. Most hatchlings leave their nests in late summer or fall, but others stay in their nests throughout winter, only leaving to seek bodies of water in the spring. (Clark, et al., 2001; Ernst and Lovich, 2009; McPherson and Marion, 1983)

Reproduction

Stinkpots are polygynandrous, and it is possible for clutches of eggs to have multiple paternities. During breeding season, males move around frequently and attempt to mate with multiple females. Females can store sperm from fall through winter and have also been observed mating with multiple males during same breeding season. ("Assessment and Status Report on the Stinkpot", 2002)

Stinkpots mate in the water. In the southeast United States, stinkpots breed throughout the year, although breeding activity peaks in spring and fall. Females lay 1 to 4 clutches per year, with 1 to 6 eggs per clutch. The maximum recorded number of eggs laid in a single breeding season was 9. Clutch size and egg size are positively correlated.

Stinkpot mating behavior can be grouped into three phases. The first phase involves tactile communication, with males chasing females, nudging their shells, biting their heads, and attempting to mount them. If a female is receptive to mating, the second phase begins. The second phase involves mounting and penetration, with males using all four feet to grasp their mate's carapace. Then, males use the scale patches on their rear legs to clasp their mate's tail, moving it to the side to expose the cloaca, and insert their penis. The third phase involves biting and rubbing, with males biting and rubbing their mate's head and neck during intromission. At the same time, females bite their mate's head and feet. Male ejaculation involves full-body contractions and stiffening. The mating behavior of stinkpots has been called forced insemination.

Stinkpots often make their nests in shady areas less than 46 m away from a body of water. They excavate shallow nests, often under logs, under leaves, or on grassy ground. Multiple females usually nest in the same area.

Stinkpots are independent immediately after hatching. Males reach sexual maturity after 5 to 6 years with an average carapace length of 63.6 mm. Females reach sexual maturity after 8 to 9 years with an average carapace length of 80.7 mm. ("Assessment and Status Report on the Stinkpot", 2002; Buhlmann, et al., 2008; Ford and Moll, 2004; McPherson and Marion, 1981; Mitchell, 1994)

  • Breeding interval
    1 to 4 times a year
  • Breeding season
    Throughout the year, although mostly in spring and fall
  • Range number of offspring
    1 to 9
  • Average number of offspring
    4
  • Average time to independence
    0 minutes
  • Range age at sexual or reproductive maturity (female)
    8 to 9 years
  • Average age at sexual or reproductive maturity (female)
    8 to 9 years years
  • Range age at sexual or reproductive maturity (male)
    5 to 6 years
  • Average age at sexual or reproductive maturity (male)
    5 to 6 years years

Females exhibit no further parental investment beyond the acts of nest digging and egg deposition. Males exhibit no further parental investment beyond the act of mating. Hatchlings are immediately independent upon hatching. ("Assessment and Status Report on the Stinkpot", 2002)

  • Parental Investment
  • no parental involvement

Lifespan/Longevity

On average, stinkpots live to be 15 to 19 years old. Mortality rates are high for hatchlings and juveniles, but low for adults. The longest recorded lifespan of a wild individual is 28 years. The longest recorded lifespan of a captive individual is 54.8 years. ("Assessment and Status Report on the Stinkpot", 2002; Mitchell, 1994)

  • Range lifespan
    Status: wild
    28 (high) years
  • Range lifespan
    Status: captivity
    54.8 (high) years
  • Typical lifespan
    Status: wild
    15 to 19 years
  • Average lifespan
    Status: wild
    15-19 years
  • Average lifespan
    Status: captivity
    54.8 years
    Max Planck Institute for Demographic Research

Behavior

Stinkpots are mostly aquatic, but will go on land during rainstorms. They often bask on branches or forking limbs overhanging water. They drop into the water from these overhangs, and there are reports of them inadvertently dropping into boats passing under such branches. It is uncommon for stinkpots to move between disjunct bodies of water.

Stinkpots brumate when water temperatures drop below 10°C. They typically enter brumation after burying themselves around 30 cm deep in mud.

Stinkpots are mostly crepuscular, although they are more nocturnal at southern latitudes because nighttime temperatures are warmer than at northern latitudes. Because they are small and ectothermic, environmental temperatures can strongly affect stinkpot activity. They mostly inhabit highly vegetated areas near water or relatively shallow aquatic zones. Stinkpots travel an average of 27 m daily. ("Assessment and Status Report on the Stinkpot", 2002; Buhlmann, et al., 2008; Rowe, et al., 2009)

Home Range

Aquatic habitat dimensions often influence home range size and shape. Recorded home ranges for stinkpots vary from less than 1 ha to more than 100 ha. On average, males have home ranges that are twice the size of female home ranges. Within their home ranges, stinkpots may use certain areas more often than others, depending on resource distribution. Resources that affect stinkpot activity include basking sites, foraging areas, and areas with microclimates that are suitable for surviving harsh conditions. Stinkpots are not known to defend specific territories. (Rowe, et al., 2009)

Communication and Perception

Stinkpots have four glands, located under their carapaces, that discharge an orange fluid when stinkpots are threatened. The fluid is a form of phenylalkanoic acid, which is mostly used to protect themselves from predators. However, it is believed that this fluid could also play a role in mating. Stinkpots get their common name due to the strong, distasteful odor associated with the fluid.

There is limited information on communication in stinkpots specifically. However, the reproductive and mating behavior of other turtles in the genus Sternotherus includes chemical communication. Turtles release chemicals in water to communicate their body size, health status, and whether they are male or female. Aquatic turtles are also sensitive to vibrations in the water, which helps them detect approaching predators and prey. They also use their senses of smell and vision to find prey in the water and on land. (Buhlmann, et al., 2008; Ibanez, et al., 2012; Mitchell, 1994)

Food Habits

Stinkpots are omnivorous, consuming a wide variety of plants and animal prey. Stinkpots mainly eat benthic and neustonic taxa. They eat plants such as algae, water lilies (family Nymphaeaceae), and seeds of both terrestrial and aquatic plants. They eat dragonflies (family Odonata), beetles (family Coleoptera), moths (family Lepidoptera), and other insects. They also eat mollusks (phylum Mollusca), crayfish (order Decapoda), and terrestrial worms (phylum Annelida). They will also opportunistically eat carrion such as dead fish and mollusks.

Stinkpots use visual and olfactory cues to detect prey. Adults mostly feed in the water, whereas juveniles and subadults (1 to 12 years old) more frequently feed on land. Stinkpots can have difficulty quickly capturing or transporting prey compared to other freshwater turtles. This is because their jaw and hyoid movements have a low integration (connection). When stinkpots are in the water, prey has to be directly in front of their mouths, because they are not able to create suction forces.

Stinkpot diets fluctuate seasonally and vary between sexes. Females consume more food than males due to the higher energetic demands of gestating and laying eggs, as well as locating nest sites and excavating nests. (Buhlmann, et al., 2008; Ford and Moll, 2004; Heiss, et al., 2010; Jackson, 2011; Mitchell, 1994; Natchev, et al., 2011)

  • Animal Foods
  • fish
  • eggs
  • insects
  • mollusks
  • terrestrial worms
  • aquatic or marine worms
  • aquatic crustaceans
  • Plant Foods
  • seeds, grains, and nuts
  • algae

Predation

Juvenile and adult stinkpots serve as prey for a variety of predators in their communities. Mammalian predators include raccoons (Procyon lotor), striped skunks (Mephitis mephitis), gray foxes (Urocyon cinereoargenteus), and North American river otters (Lontra canadensis). Avian predators include bald eagles (Haliaeetus leucocephalus), red-shouldered hawks (Buteo lineatus), boat-tailed grackles (Quiscalus major), and large wading birds, such as herons and egrets (family Ardeidae). Reptilian predators include common snapping turtles (Chelydra serpentina), northern water snakes (Nerodia sipedon), and cottonmouths (Agkistrodon piscivorus). American bullfrogs (Lithobates catesbeianus) and largemouth bass (Micropterus salmoides) also prey on stinkpots.

Humans (Homo sapiens) intentionally and unintentionally kill stinkpots during fishing activities. If they are caught on fishing lines, humans often decapitate them. Also, stinkpots can get caught in fishing traps and they drown if the traps are not checked frequently.

Terrestrial predators of eggs and hatchlings include raccoons, grey foxes, striped skunks, Virginia opossums (Didelphis virginiana), kingsnakes (Lampropeltis getula), and scarlet snakes (Cemophora coccinea). Crows (genus Corvus) will also eat eggs and hatchlings. Raccoons will follow the tracks of female stinkpots to find their nests. Some nest predators will also opportunistically kill nesting females.

Stinkpots have a tough shell that protects them and dark coloration that helps them camouflage with their environment. They release a foul-smelling, orange fluid from specialized glands when they are threatened, and will also bite in defense. (Buhlmann, et al., 2008; Mitchell, 1994)

Ecosystem Roles

A study on a stinkpot population in southern Pennsylvania found that 86% of individuals had algal colonies on their carapace. The algae was identified as either Basacladia chelonum or Cladophora kuetzingiana. Stinkpots have a mutualistic relationship with these algae, with stinkpots providing a protected substrate and algae providing natural camouflage for stinkpots. In the same study in southern Pennsylvania, a leech species, Placobdella parasitica, was observed actively feeding on 33% of the stinkpots surveyed.

Stinkpots are important bioindicators for freshwater habitats. Water pollution and other disturbances can negatively affect body mass and shell quality, which in turn can impact population size, reproductive fitness, and susceptibility to disease. ("Assessment and Status Report on the Stinkpot", 2002; Ernst, 1986)

Mutualist Species
  • Algae (Basacladia chelonum)
  • Algae (Cladophora kuetzingiana)
Commensal/Parasitic Species

Economic Importance for Humans: Positive

Stinkpots are occasionally eaten by humans, but are more commonly owned as pets. However, they are not a popular species in the pet trade and so their economic benefits to the pet trade are likely negligible. ("Assessment and Status Report on the Stinkpot", 2002; Mitchell, 1994)

Economic Importance for Humans: Negative

Stinkpots have no known negative impacts on humans.

Conservation Status

Stinkpots are considered a species of "least concern" on the IUCN Red List. In Canada, stinkpots are listed as a species of special concern. There is no known conservation status for populations in Mexico. Stinkpots have no special status on any other national or international conservation lists. They do not often venture far from bodies of water, which makes them less vulnerable to road mortality compared to other freshwater turtle species. Stinkpots have a large geographic range and are abundant throughout its entirety. Although water pollution and anthropogenic development near bodies of water can negatively impact their populations, they are unlikely to be considered threatened or endangered in the near future. In general, effective freshwater turtle conservation methods require protection of both terrestrial and aquatic habitats. There are no known conservation practices in place for stinkpots specifically.

Stinkpots are occasionally kept as pets, but are not currently at risk of over-collection. ("Assessment and Status Report on the Stinkpot", 2002; Buhlmann, et al., 2008; Klemens, 2000; Mitchell, 1994; van Dijk, 2013)

Contributors

Katelyn Lowery (author), Radford University, Karen Powers (editor), Radford University, April Tingle (editor), Radford University, Emily Clark (editor), Radford University, Cari Mcgregor (editor), Radford University, Jacob Vaught (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.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

ectothermic

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

fertilization

union of egg and spermatozoan

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.

hibernation

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.

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).

molluscivore

eats mollusks, members of Phylum Mollusca

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.

nocturnal

active during the night

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.

polygynandrous

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

scavenger

an animal that mainly eats dead animals

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

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

swamp

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

terrestrial

Living on the ground.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

References

COSEWIC. Assessment and Status Report on the Stinkpot. none. Cananda: Jonathan Edmonds. 2002.

Andres, K., R. Chambers. 2006. A test of philopatry by common musk turtles. American Midland Naturalist, 156/1: 45-51.

Buhlmann, K., T. Tuberville, W. Gibbons. 2008. Turtles of the Southeast. Athens and London: The University of Georgia Press.

Clark, P., M. Ewert, C. Nelson. 2001. Physical apertures as constraints on egg size and shape in the common musk turtle, Sternotherus odoratus. Functional Ecology, 15/1: 70-77.

Ernst, C. 1986. Ecology of the turtle, Sternotherus odoratus, in southeastern Pennsylvania. Journal of Herpetology, 20/3: 341-352.

Ernst, C., J. Lovich. 2009. Turtles of the United States and Canada. Library of Congress: The Johns Hopkins University Press.

Ford, D., D. Moll. 2004. Sexual and seasonal variation in foraging patterns in the stinkpot, Sternotherus odoratus, in southwestern Missouri. Journal of Herpetology, 38/2: 296-301.

Heiss, E., N. Natchev, C. Beisser, P. Lemell, J. Weisgram. 2010. The fish in the turtle: On the functionality of the oropharynx in the common musk turtle Sternotherus odoratus concerning feeding and underwater respiration. The Anatomical Record, 293/8: 1416-1424.

Ibanez, A., P. Lopez, J. Martin. 2012. Discrimination of conspecifics' chemicals may allow Spanish terrapins to find better partners and avoid competitors. Animal Behavior, 83/4: 1107-1113.

Jackson, D. 2011. Life in a Shell. Cambridge, Massachusetts: Harvard University Press.

Klemens, M. 2000. Turtle Conservation. Washington and London: Smithsonian Institution Press.

Lindeman, P. 2013. The Map Turtle and Sawback Atlas. Norman Oklahoma: University of Oklahoma Press.

McPherson, R., K. Marion. 1983. Reproductive variation between two populations of Sternotherus odoratus in the same geographic area. Journal of Herpetology, 17/2: 181-184.

McPherson, R., K. Marion. 1981. The reproductive biology of female Sternotherus odoratus in an Alabama population. Journal of Herpetology, 15/4: 389-396.

Mitchell, J. 1994. The Reptiles of Virginia. Washington and London: Smithsonian Institution Press.

Natchev, N., E. Heiss, K. Singer, S. Kummer, D. Salaberger, J. Weisgram. 2011. Structure and function of the feeding apparatus in the common musk turtle Sternotherus odoratus. Contributions to Zoology, 80/2: 143-156.

Palmer, W., A. Braswell. 1995. Reptiles of North Carolina. North Carolina: The University of North Carolina Press.

Reynolds, S., M. Seidel. 1983. Morphological homogeneity in the turtle Sternotherus odoratus throughout its range. Journal of Herpetology, 17/2: 113-120.

Rowe, J., G. Lehr, P. McCarthy, P. Converse. 2009. Activity, movements and activity area size in stinkpot turtles in Southwestern Michigan Lake. American Midland Naturalist, 162/2: 266-275.

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

van Dijk, P. 2013. "Sternotherus odoratus" (On-line). The IUCN Red List of Threatened Species Version 2014.3. Accessed March 28, 2015 at http://www.iucnredlist.org/details/163450/0.

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