An Overview of Common Semi-Aquatic Turtles

David T. Kirkpatrick, Ph.D

Turtles are familiar yet fascinating creatures to many people. Just about everyone can picture a turtle basking in the sunlight, stretched out on a log in the middle of a pond. Images such as this often lead people to try to keep turtles in captivity. However, to be successful with turtles a number of factors must be taken into account. Proper husbandry is a necessity, of course. Just as important is the selection of an appropriate turtle. Some turtles are easier to keep in captivity than others, adjusting more readily to a captive environment and the presence of people. This article will examine some semi-aquatic turtles that are commonly available in the United States and provide information on their natural history, allowing potential turtle owners to make informed decisions as to which turtle, if any, they wish to keep.

The Basics of Turtle Husbandry
Most of the turtles I will discuss can be kept successfully in glass aquariums, although other enclosures can be used. Unless noted otherwise, a turtle tank should contain water deeper than the turtle is wide, to allow the turtle room to flip over if necessary. The aquarium should have a filter of some type - large canister filters work better than undergravel filters. A submersible water heater is often required and a thermometer should be installed to monitor the temperature of the water. Many turtles require a land section where they can dry off - cork bark, driftwood or smooth rocks work well. If a spotlight is positioned appropriately, turtles will bask under the lights, just as they do in their natural environment. An area containing soil or sand is only necessary if you intend to breed your turtles.

Although turtles are not as susceptible to water-borne impurities as fish, clean water decreases the chance of your turtle becoming ill and increases the attractiveness of the set-up. Frequent water changes can be avoided by using a filter and by feeding the turtle in a separate container (cat litter trays filled with water, for example). Outside feeding accomplishes two things: it prevents food scraps from fouling the aquarium water, and it allows you to monitor the food intake of your turtle. Feeding should follow a schedule. Turtles are creatures of habit and will quickly learn this routine. Our adult turtles are fed every other day, and become quite excited just before their appointed meal time. Beware of overfeeding - turtles will become fat if given too much food. Obesity is as dangerous to their health as it is in humans. Vitamin and mineral supplements are important, especially for growing hatchlings and juveniles. Access to sunlight is also beneficial; outdoor maintenance of turtles gives the best chance for success. However, almost all species of turtle can be kept indoors if given the proper environment. (To read an article with a more detailed discussion of the basics of semi-aquatic turtle setups and care, click here.)

Beginning turtle keepers should start with an abundant local species of turtle. Turtles that are native to the area will not need to adjust to different climates or seasons, nor will they have endured the stresses of transport. This is why it is often easier to keep and breed local turtle species than exotic species. If at all possible, start with captive-bred turtles. Choose an animal that is alert and active. If you tug lightly on a leg, there should be firm resistance. Inspect the shell and skin for cuts, abrasions or discolored spots that might indicate sores or infections. Finally, have any turtle you purchase (captive-bred or wild-caught) examined by a veterinarian skilled with reptiles.

Commonly Available Native Species
By far the most easily recognized turtle in the United States is the Red-eared Slider (Trachemys scripta elegans). This turtle was the original dime-store turtle, until the sale of hatchlings and juveniles under four inches in length was banned in the 1970's by the Federal Government due to salmonella poisoning concerns. Red-eared Sliders over four inches long are still sold as juveniles in pet stores nationwide, and thousands of hatchlings are shipped outside the United States each year. Although many people remember Sliders as little turtles the size of a quarter, few realize that if fed and housed adequately, they can grow to be almost a foot in length! Their carapaces are disc-shaped and green with thin yellow stripes or blotches. The underlying coloration of their skin is green also, but with yellow stripes or dots on the legs and face. As their name implies, there is a red spot or wide stripe behind each eye. (Closely related turtles are sometimes found in pet stores that have different patterns and lack the red "ear". Some of these species can reach two feet in length!) Adult male Red-ears have longer tails than females, and have distinctive swordlike front claws. Adult turtles will require a very large aquarium, especially the females, which grow noticeably larger than the males. A 75-100 gallon aquarium would be suitable for an adult pair of Red-ears, for example.

A basking site is a necessity for Red-eared Sliders. They will climb onto it and sun themselves under the lights for hours at a time, with legs outstretched to absorb the warmth. In their natural habitat along the Mississippi River and its tributaries, they can often be found basking in just this manner. Sliders are hearty and omnivorous feeders if kept warm enough (water temperature in the upper 70's, basking area in the upper 80's). A varied diet of vegetables and insects, meat, fish or earthworms is essential. Alternately, trout chow or a prepared turtle food such as Tetra's ReptoMin or Wardley's Reptile Ten can be fed. With proper care, a captive life-span of over twenty years is quite possible - one was still alive at a reported age of 41 years (Slavens, 1994).

A number of other turtles can be kept in a manner similar to Red-eared Sliders. These include Florida Cooters (Pseudemys floridana), Painted Turtles (Chrysemys picta), and Map Turtles such as the Common Map Turtle (Graptemys geographica). Florida Cooters resemble Red-eared Sliders but have less decoration and a higher domed carapace. They grow somewhat larger - up to 16 inches in length. They are more herbivorous than Sliders. In the wild they congregate in large groups to bask; sometimes two dozen or more may be piled on a single log.

Painted Turtles, on the other hand, are smaller than Red-eared sliders. They are very attractive turtles, with a black shell edged with red markings and dark skin with thin yellow and red stripes. They do not grow quite as large as the Red-eared slider. They are somewhat shy in disposition and startle easily. They are not quite as hardy as Red-eared Sliders and are prone to infections if a high level of cleanliness is not maintained. Interestingly, they are the only turtle that ranges across the entire continent, with differing subspecies found in the eastern, midland, southern and western portions of the country.

Map Turtles, although perhaps the most striking of the "slider"-type semi-aquatic turtles, are the most difficult to keep successfully. They are brilliantly patterned chelonians, with fine striping on their shells and skin. Different species can be distinguished by the form these patterns take. Very wary and nervous turtles, they live in clean rivers and streams in the central and southern portions of the United States. In captivity they require pristine water conditions. Their enclosure should be placed in an area that gets little traffic, as they stress easily. The sexes are quite dimorphic, with females growing to just under twice the size of males. Map turtles should be kept only by someone with experience in keeping turtles and a willingness to devote a lot of effort and care to them.

Almost diametrically opposed to the "sliders" group in appearance, size and habits are the mud and musk turtles (Kinosternon and Sternotherus species). Where the Slider is large, brilliantly colored, and highly visible, the Mud Turtle is small, drab, and secretive. I have heard the Musk Turtle described as a "scrawny mouse hiding in a turtle shell" and the description, although inelegant, certainly fits. However, they are interesting turtles with a lot of fascinating behaviors. They often adapt well to captivity - one Musk Turtle, acquired as an adult, lived at the Philadelphia Zoo for almost 55 years (Slavens, 1994)! Although not as attractive as the Sliders, Painted or Map Turtles, their small size and hardiness make the Mud and Musk Turtles attractive choices for the novice turtle keeper.

While all four species of Sternotherus are found in the United States, only five of the 16 species of Kinosternon are located in the US; the rest occur in Central and South America. The Common Musk Turtle (Sternotherus odoratus), the Eastern Mud Turtle (Kinosternon subrubrum), Striped Mud Turtle (K. baurii) and the Yellow Mud Turtle (K. flavescens) enter the pet trade most frequently. All are smaller turtles - the largest, K. flavescens, can reach seven inches, while K. baurii and K. subrubrum don't exceed five inches and are often much smaller. Their shells are more rectangular than those of the Sliders and Painted turtles, with almost vertical sides. The different species can be distinguished by shell characteristics or markings and by patterns of striping on the skin. The Striped Mud Turtle has three distinct lines running the length of its carapace, while the Yellow Mud Turtle has a very light tan or yellow shell coloration. Mud Turtles have hinged bottom shells similar in function to the hinges on Box Turtles; the Musk Turtles lack hinges. The plastron also is reduced in size in Musk Turtles.

Due to their small size relative to the Sliders, Mud and Musk Turtles do not require as large an enclosure. A pair of turtles can be maintained in a 30 gallon aquarium quite nicely. As might be expected by their secretive nature, these turtles are not fond of basking, and so the basking area does not need to be very large. However, one should still be provided. A number of the Mud Turtle species move around on land and will benefit from a land area to investigate. Although they are called Mud Turtles, a muddy bottom is not essential for their maintenance and probably should be avoided due to the problems it causes in terms of water cleanliness. Mud and Musk Turtles prefer to have an underwater retreat; one can be provided with rocks, wood or plastic. Make sure that the retreat cannot collapse on the turtle, trapping it underwater to eventually drown!

The Mud and Musk Turtles are generally omnivores and will accept different types of plant and animal food in captivity. Although they will eventually eat prepared turtle foods, they may take some coaxing. Mud and Musk Turtles often find their food by poking along the bottom of streams, rivers or ponds. As most of the prepared foods float, it takes the turtles some time to recognize the pellets as edible.

Two other types of turtles occasionally show up in pet stores: Snappers and Softshells. However, both turtles are not suited for the beginning turtle keeper. Snapping Turtles (Chelydra serpentina) are large turtles with a carapace half-way between Mud Turtles and Sliders in shape. Their heads and heavily scaled limbs are very powerfully built. The plastron is reduced in size to an even greater extent than in Musk Turtles. Snappers grow to be quite large; turtles of up to almost 20 inches have been reported. Snappers live up to their name, especially when out of the water. Due to their large size and temperament, they are not suited for novice turtle keepers. Juveniles may look interesting, but they will quickly grow to an unmanageable size.

Softshell Turtles (Trionyx species) are bizarre-looking turtles, in that they resemble flying saucers as much as anything else. They are highly streamlined and adapted for moving rapidly through water. As the name indicates, the carapace and plastron of Softshells are leathery and flexible. Their limbs end in feet that have been modified into flippers. They have a very long neck and a head that has a very long nose with the nostrils at the very tip. Softshells are fond of burying themselves in soft sandy bottoms, and their neck and nose arrangement allows them to breathe without surfacing. Some species of Softshell Turtle grow larger than Snappers. The largest of these are generally female; Softshell males are quite a bit smaller than the females. Softshell turtles can be difficult to keep in captivity. Their sheer size requires a very large aquarium. They can be prone to infections from cuts or abrasions on their shell. In general they are aggressive and are capable of delivering nasty bites. As equally interesting and much more easily kept turtles are available, for most turtle keepers Snappers and Softshells are best observed in their natural environment.

Commonly Available Exotic Species
Most of the turtles that you might encounter in your average pet store are native to the United States. If at all possible, a beginning turtle keeper should start with a local turtle species. However, if you have some experience with turtles or can find captive-bred specimens, you might want to consider buying an exotic turtle. Decide which turtle you wish to work with, and find out all you can about it. This will enhance your chances of success. Exotic turtles (unless captive born) have undergone a stressful procedure: capture, multiple shippings, and exhibition in a pet store. Once purchased and an appropriate environment for the turtle determined and provided, exotics must still adjust to altered seasons and the presence of people. All of this stress, combined with probable poor handling, can lead to low survival rates in imported chelonians. A veterinary examination of newly acquired turtles is a very good idea. Try to purchase a breeding group of turtles at the same time from the same dealer or store, as they are more likely to be from the same region and therefore require the same environment. If you do successfully establish and breed an exotic turtle, then you can offer captive-born individuals to other turtle fanciers.

One of the most commonly seen imported semi-aquatic turtles is the Reeves Turtle, Chinemys reevesii. It is a small, hardy turtle with a lot of personality. It usually does not grow as large as a Painted Turtle, and is more rectangular in shape. Three keels, or ridges, run the length of the carapace, which is often colored some shade of brown. The Reeve's Turtle's skin is green with yellow stripes, but some individuals are very melanistic with the skin and shell a very dark brown or black. Imported from southeast Asia, including China, Taiwan and Korea, these turtles do well if given the same type of care as Sliders and Painted Turtles. As they do not grow as large, a Reeve's Turtle habitat does not have to be as large as that of a Slider, although success in breeding often requires a very large tank (Zimmermann, 1986). In their native environment (streams, lakes or ponds) Reeve's Turtles are omnivores. In captivity they will eat many different types of vegetables, or insects, earthworms and fish, as well as prepared turtle foods.

Two turtles, the Asian Yellow Pond Turtle (Mauremys mutica) and the Asian Leaf Turtle (Cyclemys dentata), resemble the Reeve's Turtle in overall size and shape. However, they are not as colorful, being solid yellow or brown generally. They are both omnivores, and a varied diet is essential for keeping them in good health. As they are somewhat more terrestrial than Painted Turtles or Sliders, a larger basking or land area can be provided. Other than that, the care for these turtles is the same as for a Reeve's Turtle or a Slider. Both the Leaf and Pond Turtle adapt well to captivity if given the appropriate environment and care.

Exotic turtles often enter the United States in waves. As one source for turtles dries up, importers turn to other sources and other turtles. The hardy African Mud Turtle (Pelusios subniger and related species) has been a large part of a recent burst of arrivals from Africa. Although called mud turtles, these turtles more closely resemble Painted Turtles in both general appearance and habits. Usually the carapace of an African Mud Turtle is some shade of brown, while their skin is yellow, ivory or gray, occasionally with a delicate vermiculated pattern of darker color. They derive their name from their habit of digging into muddy areas to escape the hottest portion of the African summer. This ability to estivate may contribute to their hardiness - imported African Mud Turtles seem to survive the rigors of capture and transport better than other species. Enclosures suitable for Sliders will serve African Muds quite well. They are avid baskers, but if a land area is provided will occasionally bury themselves for a few days, as they do in their native environment.

A few other species are seen in ordinary pet stores, but to find more exotic turtles you often need to turn to reptile dealers. Most of these exotics, including the ones I will mention next, are not suitable for beginning turtle keepers. However, in the past I have seen some specimens of Snake-neck turtles and Big-headed turtles in pet stores and as it is possible that they might once again enter the pet trade, I will describe them so that you can identify them if necessary. These imported turtles are so unique that you won't be able to forget them once you've seen one! Snake-neck turtles (of the species Chelodina and Hydromedusa) are aptly named. Their necks are very long, often almost as long as their shell. Chelodina turtles are Australian in origin, while Hydromedusa is found in South America. They are both mainly carnivorous, using their long necks to seize unsuspecting prey. Big-headed Turtles (Platysternon megacephalum) are moderately sized turtles, with a long armored tail. Their most striking feature is their huge wedge-shaped head, which is too large to retract into their shell. These turtles have developed a layer of plates on their head for protection. In some respects they resemble snapping turtles but are much more agile. In their native China, Vietnam and Thailand Big-headed Turtles are found in cold, rocky, mountain streams. They are adept at climbing and have been reported to climb trees. Big-heads are carnivorous and nocturnal, sleeping in the gravel at the bottom of streams during the day and emerging at night to chase their prey. They are poor swimmers, and should be kept in a relatively shallow aquarium with a land area, although they will not bask.

In Conclusion
If you decide that you wish to keep turtles, consider your decision carefully. Most turtles are relatively long-lived. Given proper care, turtles will outlive many other types of pet animals (including dogs and cats) and even possibly their owners! By purchasing a turtle, you are making a commitment to provide that animal with good care for the rest of its life. Assume that any adult turtle you take in will be with you for at least a decade; hatchlings for three or four times that long. Plan accordingly! If at all possible, buy a turtle that has been born in captivity, rather than collecting or purchasing a wild turtle. An ever-increasing number of people in the United States and elsewhere are successfully breeding turtles in captivity. Ask around at your local herpetological society or check classified ads in herpetological magazines to find people selling captive-born turtles. Such animals are much more likely to thrive in your care, as they have already adapted to people and your presence will not stress them. Also, captive-born turtles are less likely to be harboring parasites that could lead to future illnesses. Finally, consider adopting a turtle that is no longer wanted by its owners. Many herpetological societies have adoption programs to place unwanted reptiles and amphibians. Wild populations of turtles everywhere are threatened by the effects of the growing human population. The removal of animals from their native environment could doom the population from which they were removed. Please consider all your options carefully!

Bibliography and Other Books to Consult:

de Vosjoli, Philippe. 1992. The General Care and Maintenance of Red-Eared Sliders and Other Popular Freshwater Turtles. Advanced Vivarium Systems, Lakeside, CA.

Ernst, Carl H. & Roger W. Barbour. 1989. Turtles of the World. Smithsonian Press, Washington, DC.

Ernst, Carl H., Jeffrey E. Lovich, & Roger W. Barbour. 1994. Turtles of the United States and Canada. Smithsonian Press, Washington, DC.

Slavens, Frank L. and Kate Slavens. 1994. Reptiles and Amphibians in Captivity: Breeding, Longevity and Inventory. Slaveware Publishing, Seattle, WA.

Zimmermann, Elke. 1986 Breeding Terrarium Animals. T.F.H. Publications, Neptune City, NJ.

This article copyright 1996 by David T. Kirkpatrick. Originally published in Reptiles, March 1996, pages 32 - 46.

Reprinting of this article for non-profit purposes is permitted provided that it is unaltered and appropriate attribution, including copyright information, is included. Please notify the author of any reprinting.