Arguably one of the most common and popular exotic species of pet turtle, what the Reeve’s turtle (Mauremys reevesi) lacks in striking coloration and conventional beauty, it more than makes up for in adorable personality.
Reeve’s turtle is a member of the genus Mauremys, one of the largest genera of the Old World turtle family Geoemydidae. Although the taxonomy of this group fluctuates on occasion, at the time of writing it is generally accepted that there are eight valid species: the Vietnamese or Annam pond turtle (M. annamensis); the Caspian pond turtle (M. caspica); the Mediterranean pond turtle (M. leprosa); the Asian or yellow pond turtle (M. mutica); the Kwangtung river turtle (M. nigricans); the Reeve’s turtle (M. reevesii); the Balkan pond turtle (M. rivulata); and the golden thread turtle (M. sinensis).
Reeve's turtles. Photo by S64/Wikimedia
In terms of coloration, Reeve’s turtle is one of the least remarkable members of its genus. The carapace bears three longitudinal keels and ranges from tan to olive green to black, occasionally with faint contrasting radiation or smudging. The plastron is fairly typical of other species within Mauremys, with a base coloration of cream, yellow or tan, and gray, dark brown or black smudges. The dark smudges are centrally located on each plastral scute, and occasionally, they have radiations around their edges. The seams of the scutes are sometimes lighter than the base color on both the carapace and plastron, and fresh growth commonly appears as beige or cream. The skin of the Reeve’s turtle is adorned with soft scales, and the overall coloration is similar to that of the carapace. What little patterning that may be present is limited to the head, which varies from individual to individual and appears as cream to yellow striping, speckling or mottling. Legs and other soft parts may have lighter edging on the leg scales.
Sexual dimorphism (the visible differences between males and females) is minimal in the Reeve’s turtle. The plastron of the male is nominally concave, while the plastron of the female is flat or just slightly convex. Males also have a longer, thicker tail than the female, with the vent closer to the tip. Coloration is generally identical between the sexes, although males sometimes become melanistic as they age, to the extent that very old males appear to be carved from a lump of coal! In general, males are smaller than females and tend to have proportionally narrower heads. While most individuals do not exceed 6 inches straight carapace length (SCL), the largest M. reevesii grow to 9 inches.
The common Reeve’s turtle’s natural range extends across central and eastern China, as well North and South Korea, Taiwan and Japan. Genetic studies strongly suggest that this species’ presence on Japan is the result of several different human introductions, but the jury is still out on whether it is native to Taiwan. Research is ongoing.
It is interesting to note that, as might be expected with a wide-ranging species like M. reevesii, there appears to be several distinct morphological forms. That is, turtles from certain specific localities share distinct physical characteristics that are not seen, or at least not as common, in other localities. The typical form of M. reevesii is the familiar 4- to 6-inch brown turtle, with the occasional melanistic male. Then there is the megalocephala form, which reaches up to 8 or even 9-inches in exceptionally large females, with males being melanistic almost without exception. Additionally, certain populations of M. reevesii from Japan are consistently larger than mainland populations, and even females develop melanism in many individuals.
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Across its expansive range, M. reevesii shows a preference for slow-moving or still water. Lakes, ponds and small streams, with soft bottoms, abundant aquatic vegetation and ample basking sites are preferred. It has also been recorded in swamps, marshes and even flooded rice paddies.
Though its natural range extends into subtropical climates, the annual activity cycle of Reeve’s turtle is markedly seasonal. It is known to be active and even bask during all months of the year when conditions are favorable, but is also capable of prolonged periods of hibernation during the winter. Sometimes remaining dormant for as long as several months at a time, it likewise may aestivate for extended periods during extreme heat or drought.
Reeve’s turtles occasionally move overland for short distances, especially during rainstorms. Conversely, under severe circumstances, such as drought, they may desert a declining habitat to search for a more favorable one.
In general, M. reevesii is omnivorous, feeding on a wide variety of plants and animals. Although the broad head and massive jaw musculature of the megalocephala form suggest dietary adaptation for feeding on mollusks and crustaceans, all varieties readily consume leafy plants and algae, as well as invertebrates. Fish and amphibians are also on the menu, readily eaten live if the opportunity presents itself and dead if encountered as carrion while foraging.
Soaking up Rays
Reeve’s turtles bask gregariously, and they will often crowd a favorable basking location while jockeying for better access to the sun’s warming rays. They are a communal species, and they can frequently be observed basking in groups. In addition to raising body temperature to stimulate digestion and metabolism, the basking routine also allows the turtle’s skin to dry thoroughly, loosening the foothold of parasites and allowing shedding skin to properly slough.
Perfect for Captivity
Mauremys reevesii make wonderful captives, and their personalities and fairly small size have endeared them to innumerable turtle enthusiasts. Affording them with a captive environment that closely resembles their natural habitat will help ensure their vitality.
Although Reeve’s turtles are adapted to an aquatic existence, they are not the best swimmers. Smaller specimens especially are better suited to fairly shallow water, and even adults should be provided with ample means of climbing (versus having to swim) to the surface for air. Still, the water should be deep enough that an overturned turtle will be able to right itself and doesn’t risk drowning. The general guideline is to ensure that the water depth is always at least less than one and a half times the turtle’s shell length. For example, a minimum water depth for a 2-inch turtle would be 3 inches, and for a 4-inch turtle, no less than 6 inches. For overall volume, a single adult Reeve’s turtle should be provided a 30-gallon tank at a minimum, but a 50-gallon tank or larger would be preferable. The tank size should be increased by at least 10 to 15 gallons for each additional adult turtle.
Mauremys reevesii are lively animals and will actively utilize the entire enclosure. So long as they are provided with adequate protection from predators, seasonal extremes and escape, outdoor ponds are ideal for them. Live or artificial plants should be added to the tank for climbing and hiding, but live plants will usually be reduced to fragments as the turtles munch on them.
As described for wild Reeve’s turtles, basking stimulates metabolism to facilitate digestion and bolster the captive turtle’s immune system, as well. It also allows the skin to thoroughly dry off, which is imperative for these turtles to shed properly. So no matter the size of the turtles or the depth of the water, suitable basking areas must be provided if they are to remain healthy and vigorous. Failure to provide adequate basking amenities will potentially lead to a multitude of health problems and diseases, including skin infections, shell rot and ear abscesses, just to name a few. With a little ingenuity and creativity, various materials like natural and artificial stone, driftwood and even commercially manufactured platforms can be arranged into different configurations, providing sufficient basking opportunities.
Although M. reevesi is able to endure extreme natural conditions, artificial hibernation or aestivation in captivity is unnecessary. The turtles are sensitive to subtle seasonal fluctuations, and they will typically adjust their behavior accordingly. To prevent undue stress, temperatures are best maintained within acceptable ranges. Water temperatures should be kept between 70 to 80 degrees Fahrenheit, and air temps should be a few degrees warmer, around 75 to 85 degrees. Temperatures under the basking light should reach upwards of 85 to 95 degrees at its hottest point. These temperatures can be allowed to drop about 5 degrees at night, and another 5 degrees or so during the winter.
Although there is no perfect replacement for direct, unfiltered sunlight, providing captive turtles with a basking spot with such exposure is not always practical. Again, there are numerous varieties of retail light bulbs that will produce a suitable amount of ultraviolet light to promote vitamin D3 synthesis, which is essential to calcium metabolism and subsequently healthy shell formation. Because UVA wavelengths alone are inadequate and essentially useless for vitamin D3 synthesis, it is important that the selected bulb provides UVB wavelengths. However, if captive housing that allows exposure to direct sunlight is provided, adequate shade or other precautions should be taken to prevent accidental overheating.
Reeve’s turtles are not particularly picky at feeding time and will eagerly accept commercial food pellets, so a specialized diet is not needed. There are many brands available on the market, and anything providing a protein content of 30 to 40 percent protein, less than 20 percent fat, at least 2:1 calcium-to-phosphate ratio, and a good variety of vitamins and minerals will satisfy their dietary requirements. Additional treats, including earthworms, crickets, feeder fish, bloodworms, blackworms and various lettuces and leafy greens, such as romaine, redleaf, greenleaf, endive, escarole and kale can be provided once every week or two.
Due to their relative ease of maintenance and ready adjustment to captivity, M. reevesii is an excellent choice for the aspiring turtle breeder. A moderate investment of time and effort can result in an enormous personal reward of bringing new life into the world in the form of tiny hatchlings.
Housing males and females together is usually not a problem if ample space is provided, but behavior should be closely monitored during initial introduction and frequently during the spring breeding season. Belligerent animals of either sex should be separated at the first signs of violence and reintroduced only for brief periods for breeding under direct supervision. Reeve’s turtles are not normally considered an aggressive species, but it is always better safe than sorry. An adult pair can be comfortably kept in a 50-gallon tank, but 75 gallons or larger would be preferable.
The gestation period is brief, and the female will usually be ready to nest within a month or two after successful fertilization has occurred. The presence of shelled eggs can be ascertained by palpation. While holding the female in a head-up orientation, gently insert fingers into the inguinal cavity (the opening between the hind legs and the bridge of the shell). If eggs are present, they will feel like small, solid masses in the soft abdominal tissue. Avoid excessive pressure or the eggs could be damaged and the turtle could be injured as a result.
When gravid, female turtles may also lose interest in feeding and/or exhibit excessive basking or desire to get out of the tank. Supervised walks can be permitted in the yard to allow gravid females the opportunity to nest naturally if nesting accommodations are not provided as part of the turtle’s normal captive habitat. If this approach is not successful or not possible, as a last resort the gravid female can be induced under the care of an experienced reptile veterinarian.
Female M. reevesii are fairly prolific for a relatively small turtle. Breeding season typically commences in early spring (March) and proceeds through mid-summer (July) in the northern hemisphere. Two clutches of eggs are routinely produced per season and occasionally a third and even fourth clutch is produced. A typical clutch consists of two to six eggs, but the number of eggs decreases with each subsequent clutch. Eggs range in size from an inch long and three-quarters of an inch wide, up to an inch and a half long and one inch wide. Egg size and clutch density are directly related to the female’s size, with larger females producing larger eggs and larger clutches.
Reeve’s turtle eggs can be incubated in a variety of ways, but one consistently successful technique utilizes damp sphagnum moss as a substrate. Elaborate and expensive incubators are not necessary, and in some instances even detrimental to the development of the embryo. Humidity is extremely difficult to control in forced-air type incubators, and they are best avoided. Simple wafer-type thermostats have proven very reliable, and are recommended for their ease of use. Having both a primary and backup thermometer is recommended to ensure that the incubation temps remain in the 80- to 84-degree range that is optimal for healthy embryo development and hatching. The sphagnum moss substrate can be remoistened as required to prevent desiccation and failure of the eggs.
After roughly 50 to 80 days, the eggs will typically begin to sweat within a few days of hatching. Hatchlings may fully emerge from the egg within several hours, but it is not unheard of for them to take several days. Hatchlings with sizeable residual yolk sacs should remain in the incubator long enough for full absorption. After the yolk is absorbed and the umbilical scar is fully closed, they can be removed from the incubator and set up as previously described.
Endearing and Adorable
With their manageable size, pleasing appearance and amenable personalities, Reeve’s turtles are delightful creatures. Though they lack vivid coloration, their inquisitive and sociable nature makes them a perpetual favorite for many turtle enthusiasts. It is likely that any keeper who does not love Reeve’s turtles simply has never had a Reeve’s turtle! REPTILES
PAUL VANDER SCHOUW is an avid turtle hobbyist from west-central Florida. A mechanical engineer by profession, he has about 1,000 individual turtles representing more than 100 species and subspecies. He has successfully bred more than half. Chelid side-necked turtles are his primary interest.