The Family Kinosternidae
The family Kinosternidae is a moderately sized family of chelonians. There are two subfamilies, the Staurotypinae and the Kinosterninae, each of which have two genera. The genera of the Staurotypinae, Claudius and Staurotypus, are endemic to central Mexico and range south into northern Central America. The Kinosterninae genera, consisting of Kinosternon and Sternotherus, range more widely, occurring from southern Canada through much of South America.
The Subfamily Staurotypinae
The turtles in the subfamily Staurotypinae are all moderately large musk turtles. All three turtles have three keels running the length of the carapace. Their plastron is small and narrow, cruciform in shape, with seven or eight scutes. Some researchers regard the Staurotypinae as distinct enough from the Kinosterninae to warrant elevation to full family status, as the family Staurotypidae (Bickham et al., 1983). They base this elevation on chromosomal variations, but a number of other studies on morphological variation within the Kinosternidae support the current system.
The genus Claudius contains only one turtle, Claudius angustatus. The plastron of the Narrow-bridged Musk Turtle has seven bones, unlike any other turtle. Another unique feature is the presence of two cusps on the turtle's upper jaw.
Two species, Staurotypus salvinii and Staurotypus triporcatus, make up the genus Staurotypus. These turtles are the largest in the family; S. salvinii (the Pacific Coast Giant Musk Turtle) can reach a length of 25 cm, while S. triporcatus (the Mexican Giant Musk Turtle) grows to almost 40 cm. They can be distinguished from any other member of the Kinosternidae by their size.
The Subfamily Kinosterninae
The subfamily Kinosterninae is a much larger and more varied group than the Staurotypinae. Turtles in the Kinosterninae subfamily can be distinguished from Staurotypinae chelonians by the number of plastral scutes. Turtles in the Kinosterninae have ten or eleven scutes compared to the seven or eight in Staurotypinae. Another diagnostic feature of the subfamily is the absence of the entoplastral bone present in the Staurotypinae, although this characteristic is less useful when comparing living turtles.
Two genera are present in the subfamily, the genus Kinosternon (mud turtles), with at least fifteen species and a number of subspecies, and the genus Sternotherus (musk turtles), with four species, one of which has two subspecies. Musk turtles are native to the United States, with one species (S. odoratus) ranging up into Canada. Mud turtles are more widely dispersed, with species found from Connecticut (K. subrubrum) south through the southern and central portions of the United States, through Mexico and Central America, and entering South America as far as northern Argentina (K. scorpioides).
In recent years there has been a large amount of scientific debate over the degree of separation within the Kinosterninae. Some researchers believe that the two genera should be combined into one genus, Kinosternon. Others favor maintaining the split. The most recent controversy arose in 1986 when Seidel et al. published a report on a detailed comparison of the variation in thirteen protein complexes in 18 species within the family Kinosternidae. The variation among the thirteen proteins was not great, and analysis of the data supported many of the conclusions of other researchers based on morphological data (such as Bramble et al., 1984) and karyotyping (Sites et al., 1979). However, based on their data, Seidel et al. argued that two members of Kinosternon, K. baurii and K. subrubrum, were more similar to members of Sternotherus than to species of Kinosternon located in Central and South America. Sites et al. had noted a similar result based solely on karyotypes of the various species, but did not suggest any revisions in taxonomy. Based on this relationship, Seidel et al. relegated Sternotherus to subgeneric status (i.e. Sternotherus odoratus becomes Kinosternon odoratum, etc.). A few years later, John Iverson published a work using a very large data set of variable morphological features (Iverson, 1991) to resolve phylogenies within Kinosternon and the possibly suspect Sternotherus. As he could find no unique character diagnostic for Sternotherus turtles, Iverson followed the taxonomy suggested by Seidel et al. Some authors also adopted the revised Kinosternon genus; others have remained unconvinced. In Ernst and Barbour's 1989 Turtles of the World, they included Sternotherus in Kinosternon. However, with the publication of the 1994 volume Turtles of the United States and Canada, Ernst, Lovich and Barbour question the split, wondering "why not relegate K. baurii and K. subrubrum to the genus Sternotherus rather than the four Sternotherus species to Kinosternon?" (pg 138). Obviously, the jury is still out on the status of Sternotherus.
Habitat for mud and musk turtles varies depending on the species, but in general they prefer slow-moving or still bodies of water. Preferred locations often have soft-bodied beds, either consisting of sand or mud, and support a large amount of aquatic vegetation. Utilization of specific habitats can be the result of a complex interaction of factors, even among turtles within a particular species or subspecies. Intrinsic properties of the location, including type of substrate, presence of vegetation, and water flow, interact with other factors such as abundance of local predators, alteration in the habitat (either naturally or by human intervention), and variable local climatic conditions. Some research has been done to evaluate the relative importance of these factors (see, for example, Webster, 1986, Christiansen et al., 1989, and Stone et al. 1993). Basking sites are not essential, but some species will take advantage of spots if they are available. Sternotherus odoratus has been reported to climb trees, edging out on branches meters above the water, and dropping into the water below when disturbed. The loggerhead musk turtle, S. m. minor, shows similar tendencies (Pritchard, 1979). Some species, especially those located in drier regions, inhabit temporary bodies of water. In the dry season the turtles will estivate in the dried mud, waiting for rainfall to replenish the water supply.
The three turtles in the Staurotypinae subfamily (S. salvinii, S. triporcatus and C. angustatus) are distinguished by the presence of three keels running the length of the carapace, their size (in Staurotypus) and their aggressive disposition. C. angustatus also has two distinct cusps on its upper jaws to identify it. S. salvinii can be distinguished from S. triporcatus by its smaller size and also by its wider and more flattened carapace.
Four species of Sternotherus are recognized. Sternotherus carinatus, the Razor-backed musk turtle, deserves its name. This turtle has a very sharply sloping carapace - when viewed from the front, the turtle appears to be triangular. The plastron only has ten scutes, unlike the rest of the species of Sternotherus and Kinosternon. The Flattened musk turtle, S. depressus, also is aptly named. Its carapace is very flattened and wide. It has been considered a subspecies of S. minor in the past. The Loggerhead musk turtle, S. m. minor, has a carapacial shape that is intermediate between S. depressus and S. carinatus. Like the rest of the genus, S. minor species have a single weak hinge between the abdominal and pectoral scutes of the plastron. S. minor peltifer differs from the Loggerhead musk by the presence of strong stripes on its neck. The most commonly known musk turtle, S. odoratus, the Common musk turtle, or Stinkpot as it is occasionally called, has a small plastron and two distinctive stripes on each side of the face, running back from the snout and going to either side of the eyes.
Five species of Kinosternon are found in the United States. Possibly the most easily recognized is K. baurii. This chelonian is small, even for mud turtles, and has three light stripes running the length of the carapace. As with all mud turtles, it has two strong plastral hinges. Overlapping geographically with the Striped mud turtle is the Common mud turtle, K. subrubrum. This turtle is also small, but lacks the carapacial striping. It is rather nondescript, with only occasional markings on some specimens, usually in the form of yellow mottling or faint stripes on the head, especially in K. s. hippocrepis. This subspecies is sometimes confused with K. baurii, which it greatly resembles except for the carapacial striping. Further west, one encounters the Yellow mud turtle, K. flavescens. The carapace is a drab olive or brown, while the skin is yellow, ranging to grey. Two other species just enter the United States: K. hirtipes and K. sonoriense. The Sonoran mud turtle is a medium sized mud turtle, somewhat elongated, with an olive-brown carapace and grey skin with darker mottlings. Only one subspecies of the Mexican mud turtle, K. hirtipes murrayi, enters the United States, down in Texas. This species has three carapacial keels, while the skin is dark with a fine reticulated pattern on the head.
The majority of mud turtles are located in Mexico, Central and South America. A number of these, including K. herrerai, K. angustipons, K. dunni, and K. creaseri, have only been cursorily described, especially details of their natural history. Other species may also exist; Iverson (1992) indicates that K. integrum actually harbors a second undescribed species. Some of the more distinguished species of mud turtles are K. leucostomum, the White-lipped mud turtle, and K. scorpioides, the Scorpion mud turtle. The White-lipped mud turtle has a dark carapace, with a yellow plastron. Befitting its name, the edges of the jaws are cream, sometimes interrupted by dark smudges. The Scorpion mud turtle group (there are six recognized subspecies) contains the Red-cheeked mud turtle, K. s. cruentatum. Individuals of this species are moderately large, with carapaces bearing three keels. The carapace itself is yellowish and the plastron shades into an orange cast. Most strikingly, the sides of the turtle's head can be red or orange, giving the turtle its common name.
To the untrained eye, many of the mud and musk turtle species appear very similar. This similarity is complicated by the presence in wild populations of individuals that are intergrades or hybrids between differing populations and species. Without a positive identification, obtaining information on a specific turtle can be almost impossible. Fortunately, two keys have been published in the last few years that are of enormous utility in distinguishing the species of Kinosternon (and Sternotherus, although both keys place Sternotherus in Kinosternon). The first key is in Ernst and Barbour's Turtles of the World (page 73), while the second is in John Iverson's A Revised Checklist with Distribution Maps of Turtles of the World (pages 214-215).
In the genus Staurotypus, the males have longer, thicker tails than the females, and also possess rough scales called vinculae on their thighs (Ernst et al., 1989, Platt, 1993). Males of Claudius angustatus have similar differences, and also have a horny tip on their tails (Ernst et al., 1989, Platt, 1995). Staurotypus turtles have heteromorphic sex chromosomes: males are XY, while females are XX. However, unlike other species with similar arrangements, the X chromosome is more evolutionarily derived than the Y chromosome, and so the XY male is an intermediate between the ancestral form and the more divergent XX female (Sites et al., 1979).
In the subfamily Kinosterninae the males of all species possess a longer, thicker tail than the females (Ernst et al., 1989) (see Figure 6). Many also have vinculae and horny tips on their tails. However, some species lack these tips, or both females and males possess them (K. flavescens, K. herrarai, and K. oaxacae, for example). In a number of species (K. dunni, K. alamosae, K. hirtipes, K. integrum, and K. leucostomum) the male turtle is larger than the female, although in K. acutum, K. angustipons and K. sonoriense females are larger than males. Some species have other sexually dimorphic characteristics. For example, the male Narrow-bridged Mud turtle (K. angustipons) has an enlarged snout. Finally, the plastron of the male in a few species has a slight concavity.
Very little has been published on the reproduction of either Staurotypus or Claudius. Details of mating behavior in the wild are undescribed. Elke Zimmermann, in her book Breeding Terrarium Animals (Zimmerman, 1986) gives a detailed description of mating observed in captive Staurotypus salvinii. Many of the motions are similar to those exhibited by Kinosternon and Sternotherus turtles. From captive breeding at the Columbus Zoo it appears that male to male combat helps ensure fertilization (Platt, 1993). In Staurotypus triporcatus, an average clutch size is nine eggs, with more than one clutch possible in a season. As might be expected from the presence of sex chromosomes in Staurotypus, they do not seem to exhibit temperature-dependent sex determination (although see Ewert et al., 1991, for some potential complications). Claudius angustatus also exhibits no temperature-dependent sex determination (Vogt et al., 1992). This species probably lays multiple clutches during the year, although the number of eggs deposited is lower (Flores-Villela et al., 1995). Eggs are deposited in nests in mats of vegetation, rather than being buried. Although incubation times in the wild are unknown, captive incubation is variable but long, ranging from 95 to 229 days (Flores-Villela et al., 1995). Staurotypus eggs will hatch after 145 days at 25 - 30 degrees C.; Claudius eggs only take approximately 90 days (Zimmermann, 1986).
Courting and mating has been described in detail for a number of species in the subfamily Kinosterninae, especially the North American forms (for an overview see Ernst et al., 1994 and references therein, but also see Mahmoud, 1967 and Bels et al., 1994). In general, kinosternids do not have an elaborate courtship procedure, although there are a number of variations dependent on species. Typical events include a phase where the male follows the female, sniffing at her cloaca and sometimes the bridge between the carapace and plastron. This occasionally is accompanied by a head-to-head confrontation or nudging by the male. If the female moves away, the male will give chase, repeating the sniffing and nudging until the female remains stationary. The male then mounts the female from the side or rear, using all four feet to grasp the shell. When actual copulation takes place, the male may move backward or up at an angle to the female's carapace. These motions can depend on the relative size of the individual turtles and on the specific species involved, as tail length and location of the vents may contribute.
Egg deposition varies between the species and even among individuals within a particular species. Some choose to bury their eggs, while others deposit them under vegetation or in other enclosed areas. Most species of mud or musk turtles lay multiple clutches of eggs during a single season, with a relatively low number of eggs deposited each time (from one to five, on average). Incubation times are dependent on local conditions and the exact species, but eggs seem to take from three to five months to hatch. Mud and musk turtles exhibit temperature-dependent sex determination - eggs incubated at an intermediate temperature range generate predominantly males, while females are produced at temperatures above or below this temperature interval (Ewert et al., 1991). Eggs should be incubated in damp medium (sphagnum moss or a dirt/vermiculite mixture hold water well, for example) at temperatures ranging from 25 - 30 degrees C. In Sternotherus odoratus, for example, almost all eggs incubated at 25 degrees C result in male turtles, while almost all eggs incubated at 30 degrees result in females (Ewert et al., 1991). Incubation times range from three months to over six months, depending on the temperature and the species of turtle (Zimmerman, 1986).
Growth and Development
Hatchlings of some of the smaller mud turtle species are among the smallest in the world. For example, hatchling S. odoratus are only approximately 20 mm in length, while hatchling K. baurii can be as small as 16.5 mm (Ernst et al., 1994). The size of the hatchlings is dependent on the size of the eggs, which in turn is dependent on the size of the female laying the eggs. Although mud and musk turtle hatchlings resemble their adult counterparts, some differences are demonstrable. In particular, some species have more dramatic markings as hatchlings. The Loggerhead musk turtle (S. m. minor) has a pinkish plastron, while the other subspecies, S. m. peltifer, has a yellow-orange cast to the plastron and a striped neck. The head stripes on hatchling S. odoratus are very noticeable, also. Intriguingly, Britson and Gutzke speculate that these colorations may be warning signs to predatory fish. In experiments with largemouth bass, fish initially attempted to eat hatchling turtles, but quickly learned to reject them. Apparently the violent motions of the ingested hatchlings were harmful to the gills or digestive tract of the fish (Britson et al., 1993).
Growth rates of hatchlings and juveniles are dependent on local conditions, including the available amount of food, the length of the year available for feeding based on climate, and other variables. Breeding size may not be reached for up to a decade for some individuals, especially in regions where activity is limited by adverse conditions. However, mud and musk turtles can live to an advanced age. Ages in excess of two decades are not uncommon, and one S. odoratus lived over 54 years at the Philadelphia Zoo.
Selection and Acquisition
Selection of mud and musk turtles will depend on the purpose for which the turtle has been acquired: as a pet, for short-term observation in captivity, or for long-term maintenance to investigate details of the turtle's lifestyle, including breeding. If the turtle is to be a pet, attempt to locate a breeder of mud and musk turtles - they do exist, and more herpetoculturists are working with kinosternids every day. Captive-born chelonians are the most likely to be disease-free and to acclimate to captive maintenance with a minimum of problems. If captive-born turtles can't be located, purchase a turtle from the local area, or at least within the United States. Much more is known concerning the natural history of North American kinosternids than of the Central and South American forms, making it easier to design an appropriate enclosure and provide an adequate diet.
A few things should be mentioned when keeping mud or musk turtles to observe details of the turtle's life cycle for a short term, as this generally involves collecting local specimens: 1) try not to stress them as even short captive periods can conceivably cause a potentially fatal buildup of internal parasites, 2) don't mix specimens from different locales (this increases the chance of disease spread, and might mix up differing genetic pools), and finally, 3) don't release a turtle if it appears to be suffering from an illness acquired in captivity.
For long-term studies or breeding purposes, attempt to acquire turtles from the same area, to lessen the chances of accidentally mixing up unknown subspecies. If the turtles are imported, get as much data as possible from the importer if you are not acquiring the animals yourself. Specific collection sites, habitat at the collection site, and similar data can be invaluable in setting up an appropriate captive environment. If possible, check the health of the turtles before purchase - examine them for injuries, overall appearance, and sex. After acquisition, all animals, whether captive-born, locally collected, or imported, should be examined for parasites, both internal and external, and quarantined.
Staurotypus, Claudius, and a number of the species of Kinosternon and Sternotherus are nocturnal or crepuscular in habit. This tendency may make it harder to observe behaviors in captivity. Some species, such as K. flavescens, are primarily diurnal, however. Activity patterns may also change over the course of the year, depending on environmental conditions. Turtles from the northern part of the family's range usually hibernate for a portion of the year, while turtles in hot, dry regions may estivate during the hottest portion of the year, especially if the local water sources dry up. Although kinosternids usually are considered to be chiefly aquatic in nature, some species spend a reasonable amount of time out of water. For example, S. carinatus is active in the afternoon and can be found basking (Ernst et al., 1994). K. subrubrum and K. baurii are often found moving around on land.
In temperment many of the kinosternids are generally shy and retiring turtles. Exceptions to this are S. triporcatus and S. salvinii. C. angustatus has also been known to be aggressive (Platt, 1995) when handled. Newly caught individuals of other species may also bite - Pritchard reports a particularly painful bite from the Florida mud turtle, K. subrubrum steindachneri (Pritchard, 1979).
Detailed life histories for a number of members of the family Kinosternidae have been published. If you intend to keep any of these chelonians, these publications are invaluable starting point, and careful attention to the data given therein will greatly improve the husbandry of your turtles. A number of these publications are listed in the references section.
Mud and musk turtles are easy turtles to handle, in general. Newly captured or extremely stressed musk turtles will exude a yellowish compound from glands under the rim of their shell. This liquid has a rather pungent odor, thus the common name for the group (although all kinosternids possess the glands). Captive individuals usually lose this habit quickly. Even newly-hatched turtles are capable of producing musk and will do so readily if disturbed. Some of the larger species in the family Kinosternidae are capable of delivering a strong bite, and should be handled with care. In particular, the two species of Staurotypus are known for their tendency to bite, in addition to a rather fierce temper that does not diminish with length of time in captivity. For these reasons, handling of these two turtles in particular should be kept to a minimum.
Mud and musk turtles can be maintained in captivity if care is taken to address their environmental needs. Depending on the species of kinosternid and the local environment, outdoor maintenance can be considered for part or all of the year. Animals kept outside will require a water area and a land area. The areas should be enclosed in a fence constructed in such a manner that the turtles cannot get through or under it. As mud and musk turtles are occasionally preyed upon by large birds or climbing animals such as raccoons, it might be necessary to cover over the whole enclosure to prevent loss of turtles. Outdoor maintenance has the advantage of giving the turtle a more natural environment, but often does not allow the keeper to closely observe the turtle, for signs of illness for example.
Indoor maintenance most likely will be the norm. As the majority of the kinosternids are relatively small animals, suitable environments can be created with commonly-available aquariums. Smaller mud turtles, such as K. baurii or K. subrubrum, will do well in a 20 or 30 gallon aquarium, while the larger species require more spacious accomodations. The Giant Musk Turtles can grow large enough to require specially constructed enclosures. Although generally considered to be mainly aquatic in nature, many of the mud and musk turtles will roam on land, and will benefit from the presence of a land section in their enclosure. An area of sandy dirt of sufficient depth to permit egg deposition is a necessity if breeding is planned or might occur. Land areas can be constructed in aquariums by walling off a section of the tank with silicone aquarium sealant and appropriately sized pieces of glass or plastic. A more economical use of the space is to make a suspended 'island' in the tank with three pieces of plastic: two positioned vertically and one running horizontally, parallel to the tank bottom but suspended a few inches above it. Access to the land area can be provided by conveniently placed rocks, wooden cork floats, or ramps constructed of plastic. Depending on the setup, the land area can be made accessible from both sides, but animals can still pass underneath it. If the land 'island' is placed at one end of the tank, an underwater 'cave' is created. Many kinosternids take advantage of naturally occurring underwater shelters created by rocks or tree roots, and will use the artificially created cave in a similar manner.
Tank decorations can range from minimal to elaborate, depending on the desires of the turtle-keeper but keeping in mind the natural environment of the species of chelonian being kept. If one of the goals is to observe natural behaviors of the turtle, a setup that duplicates the native habitat as closely as possible might be necessary. At the other extreme, a minimalistic setup might be used for its ease of maintenance. Depending on the species, the bottom substrate could consist of sand, gravel, or a layer of silt, or be left bare. Piles of rocks, wooden logs or cork-bark floats can all be provided. Broken clay pots often make suitable underwater caves. Tank decorations will increase the maintenance required to keep the water clean, as they provide inaccessible areas where dirt can accumulate. They must also be arranged carefully; if a turtle becomes trapped underwater by poorly designed cage decorations the turtle can drown before its plight is noticed. Plants, both aquatic and terrestrial, may need to be replaced periodically if provided, as they may become sources of food for the turtles. Finally, most, if not all, of the mud and musk turtles are active foragers, and will dig up or otherwise disturb aquarium decorations or plants while hunting for food.
Filtration of the water is a necessity for most aquatic turtle setups. In general, the larger the filtering unit, the better in terms of ease of maintenance and water cleanliness. Canister filters, either submerged or placed outside the tank, generally work well. Undergravel filters may be overloaded by waste material, especially in smaller aquariums. The rate of water exchange should also be considered when constructing the enclosure. Some species of kinosternid chelonians prefer still or slow-moving water, and may suffer if placed in a setup with a high volume of water flow.
The temperature of the water will depend once again on the exact species of mud turtle. Those from the northern part of the family's range, such as S. odoratus or K. subrubrum, may not require much heating and might benefit from a cooling off or hibernation period in the winter, while those from the southern part of the range may require supplemental heating all year. Submersible heaters that can be set to maintain a desired temperature work well in mud and musk turtle enclosures. Care should taken to ensure that the heater is protected from accidental breakage, but it should not be blocked off to such a degree that water flow around the heater is impaired. The rooting and digging tendencies of most mud and musk turtles must be considered, also.
Lighting will depend on the type of mud or musk turtle being maintained. Many of the kinosternids are nocturnal or crepuscular, and of those that are not, many more do not bask and so will not use basking lamps very often. For similar reasons, the use of full-spectrum bulbs may not be required. However, if any plants are kept in the enclosure, they will benefit from the full-spectrum lighting, and it certainly won't hurt the turtle if it is provided. The turtle will still require a normal day/night cycle, and so lights should be provided with a cycle keyed to either the outside environment (especially if the turtle is kept in a room with windows) or to the day length in their native environment. The amount of seasonal variation in day length is also dependent on the specific species of turtle being kept.
Kinosternids are opportunistic omnivores or carnivores. They will eat many different types of food, depending on what is available in the local environment. The members of the subfamily Staurotypinae are almost entirely carnivorous, feeding on aquatic insects, snails, clams, fish, worms, crustaceans and possibly amphibians (in Claudius) and other turtles (in Staurotypus). It has been speculated that the upper jaw cusps in C. angustatus may be used to grasp soft-bodied prey such as frogs (Platt, 1995). Platt (1993) reported that captive S. triporcatus take fruit in captivity.
Food items in the subfamily Kinosterninae vary depending on the local environment and the species. If other turtles are present, competition for food items may alter what the turtles will consume. For example, in studies in Belize with K. leucostomum, K. scorpioides, S. triporcatus, and Trachemys scripta showed that diets altered as relative densities of turtles changed (Vogt et al., 1988 and Moll, 1990). Many of the items listed for Staurotypus and Claudius are consumed by Kinosternon and Sternotherus species, and some will also eat aquatic vegetation of various types.
In captivity kinosternids will eat many of the items that they eat in their natural habitats. Various insects, earthworms, and fish are all readily consumed. For those species that are omnivorous, vegetable matter should be offered on a routine basis. Commercial turtle foods and trout chows will be accepted by most kinosternids, although it may take a period of acclimation. Turtles should not be allowed to become fixated on any particular food; items should be varied to provide a complete diet. Periodic supplementation with vitamins and calcium may help prevent deficiencies due to undetected inadequacies in diet. Captive turtles in the author's collection are fond of calcium blocks made of plaster of paris with added vitamin and calcium powder. In addition to the benefits from the calcium and vitamins, the blocks also help keep a turtle's jaws worn down. A final note of caution: some of the more aggressive species have been known to bite at cagemates during feeding, sometimes leading to loss of limbs (see for example the report on K. scorpioides in Pritchard et al., 1984).
Most waste material can be eliminated or greatly reduced by feeding the turtles outside of their enclosure. To do this, simply fill a plastic container (cat litter trays work well, for example) with water, place the food into it, and then put in the turtle. After the turtle has consumed all the food it is interested in eating, replace the turtle in its enclosure and dispose of the dirty water. In addition to the elimination of food debris, this method also helps reduce fecal material in the aquarium, as many chelonians will defecate just prior to or immediately after feeding. An added benefit of exterior feeding is that it allows you to monitor the food intake of each turtle, and at the same time keep a check on the relative health of the chelonians. In addition to feeding outside of the main aquarium, a filter is a necessity for reducing the amount of waste material in the captive environment (see above).
Preventative Health Care
Newly arrived individuals must be quarantined, even if they were captive-born and raised. A month of quarantine is recommended; longer is always better. Without quarantine, whole collections can be wiped out through the introduction of a novel disease or parasite to which the older chelonians have no resistance. New turtles should also be examined for the presence of internal and external parasites. Mud and musk turtles are capable of harboring a wide range of parasites, including leeches, roundworms, tapeworms, and protozoans. Some turtles will also be covered with algae (see Figure 10). Ernst and Barbour, in their 1972 book Turtles of the United States, give a list of parasites that have been identified as infecting various turtle species, including the North American mud and musk turtles. Treatment for any detected parasites will vary depending on the level of infection and the organism responsible. Veterinary aid should be sought if you are unfamiliar with parasite detection and elimination.
Once a turtle has been established in captivity, health care falls into three major categories: prevention of incidental infections, treatment of injuries, and dietary considerations. Incidental infections such as respiratory illnesses, scute infections, or parasite infestations can be controlled or eliminated by careful monitoring of the animals and their environment. This includes cleaning the aquarium at regular intervals, water changes, and quarantine for any new or ill turtles. Injuries can occur because of improper cage design (sharp rocks, for example) or through aggressive interactions with other turtles. Frequent examinations of the turtles for injuries, and prompt attention to any injuries discovered, will prevent minor cuts and abrasions from becoming infected. Wounds can be cleaned with diluted iodine or betadine or a mixture of both. Topical polysporin ointments work well on minor injuries, and have the advantage of being relatively water-insoluble. If one turtle consistently harasses other cagemates, a separate enclosure should be provided. The final major source of illness in turtles in captivity is failure to provide a complete diet. The turtle should not be allowed to become fixated on one food item; instead, a variety of foods should be offered. Even turtles who are carnivorous will occasionally take some plant matter, for example. Periodic supplementation with vitamins and calcium, usually in the form of a powder sprinkled on food or a liquid injected into a favorite prey item, is helpful.
Female turtles that are being bred or who are known to have mated require special care. They should receive a well-rounded diet, with increased supplementation of calcium. Also, changes in behavior should be noted carefully. If the enclosure is unsuitable, for example, the female may retain her eggs rather than laying them in an area she is not satisfied with. Retained eggs can lead to health complications, especially if an egg ruptures or becomes over-calcified. Changes in behavior, such as loss of appetite or restlessness, in females known to be carrying eggs should serve as a warning signal to keepers.
Problems with kinosternid turtles usually can be grouped into two distinct categories: 1) problems endemic to wild-caught turtles, and 2) problems related to incorrect husbandry.
1) As virtually all specimens encountered will be wild-caught individuals, the usual problems associated with free-living animals will be evident. All turtles should be checked for parasites, both internal and external. Ticks are not often encountered, given the aquatic lifestyle of most of the species in the Kinosternidae family, but occasionally leeches are found on freshly-caught individuals (see, for example, Ernst, 1986). Internal parasites can also cause problems in freshly caught individuals. Turtles can be infected with nematodes, trematodes, and protozoans. For a detailed list of species of parasitic species found on mud turtles in the United States, see Ernst and Barbour's Turtles of the United States (1972). The stress and debilitating conditions suffered by chelonians during capture and transit can lead to a potentially fatal buildup in internal parasites, especially if the turtles have been grossly mishandled. All new arrivals should be examined and treated as appropriate, especially if high levels of parasites are detected. These problems can be alleviated or eliminated by obtaining captive-born individuals when possible.
2) Lack of knowledge on basic natural history for many of the kinosternid species from Mexico, Central and South America can lead to problems. Careful experimentation with husbandry may be necessary if information on dietary and habitat preferences is unavailable. Unfortunately, inadequacies in husbandry may take months or years to become apparent and without careful observation may go unrecognized until too late.
Flores-Villela, OA; Zug, GR: Reproductive biology of the chopontil, Claudius angustatus (Testudines: Kinosternidae), in southern Veracruz, Mexico. Chelonian Conservation and Biology, 1995; 1(3): 181-186.
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