The river cooter ( Pseudemys concinna) is a freshwater turtle species native to the central and eastern United States. These turtles, also known simply as cooters (Pseudemys sp.), are popular in the pet trade due to their affordability and interesting color variations. However, potential owners should be aware of their specific needs, particularly regarding diet and feeding habits, to ensure their long-term health and well-being.
River Cooter Characteristics and Habitat
River cooters are relatively large turtles with a carapace (upper shell) that can reach 12-16 inches in length. The carapace is typically dark greenish-brown with numerous yellow lines or markings, including backward-facing C-shaped marks on the first, second, and third pleural scutes (rib-covering shell scales). The plastron (bottom shell) is yellow to reddish-orange with a dark pattern between scutes that follows the scute seams (this fades with age). The exposed skin on the head, limbs, and tail may be olive brown or black, with many yellow lines. A yellow Y-shaped marking is usually present on either side of the head and neck.
These turtles are found from Virginia south to central Georgia, west to eastern Texas, Oklahoma, and north to southern Indiana. They inhabit various freshwater and even brackish locations, including rivers, lakes, ponds, and tidal marshes with heavy vegetation. River cooters prefer slow to moderate moving rivers and streams. All species prefer to live in bodies of water that are abundant with aquatic vegetation. They are often seen basking on logs or sun-warmed rocks, sometimes in the company of other aquatic basking turtles like sliders and painted turtles.
There are similarities in appearance across all cooter species: they all have moderately to highly domed shells, yellow to cream stripes on their heads and limbs, females grow larger than males, the shells on male turtles are less domed, and males have longer claws.
Florida is home to several species and subspecies of cooters: the river cooter, Florida cooter, Florida red-bellied cooter and Suwannee cooter. The Suwannee cooter, a species covered by Florida’s Imperiled Species Management Plan, is the largest cooter in the state. The shell is highly domed with a black to dark brown base color. The shell pattern is made up of green, yellow, brown and/or black markings. A light backward-facing ‘C’ shaped mark can be seen on the second scale (scute) of the shell. The bellies are yellow to orange with black pigment along the seams. Adult size ranges from 9-13 inches with a maximum shell length of 17.2 inches. The elongated shell is moderately domed, with a dark brown or black base color, and yellow or orange lines. The belly is plain yellow. The shell is black and highly domed with reddish to yellow-orange vertical stripes on each scale. The belly is yellow orange to reddish. Adult size ranges from 8-12 inches with a maximum shell length of 14.8 inches.
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Dietary Habits in the Wild
River cooters are primarily herbivores, especially as they mature. Their diet mainly consists of aquatic plants, grasses, and algae. They feed on various types of aquatic plants and marine flora. They also consume water plants, algae, pondweeds, fallen leaves, and seeds of trees. River cooters have tooth-like cusps in the upper jaw, which are likely an adaptation to aid in eating leaves and fibrous vegetation.
Younger river cooters tend to seek a more protein-enriched diet, including aquatic invertebrates, crustaceans, and fish. While some believe that these turtles will not eat meat, predatory behavior has been observed. They have been observed eating carrion found along the river's edge. Although this animal cannot swallow out of water, it will leave the water to retrieve a tasty bug or worm, returning to the water to swallow. Cooters will also enthusiastically chase, kill, and eat small fish.
River cooters are generally solitary creatures often seen basking on logs or sun-warmed rocks. Diurnal by nature, River cooters wake with the warming sun to bask and forage.
Feeding River Cooters in Captivity
In captivity, replicating the natural diet of river cooters is crucial for their health and well-being. A varied diet is key, with an emphasis on plant-based foods.
Recommended Foods
- Aquatic Plants: Duckweed, water lettuce, and water hyacinth are excellent choices.
- Vegetables: Mustard greens, turnip greens, dandelion, spinach, carrots, and zucchini are all suitable options.
- Fruits: Fallen fruits can be offered as occasional treats.
- Commercial Turtle Pellets: High-quality turtle pellets can supplement the diet, but should not be the primary food source.
Supplementation
Calcium is a vital component of a river cooter's diet, essential for shell and bone development. Phosphorus is in most of the foods that turtles eat. It is the calcium side of the ratio that demands attention. Supplementation isn’t necessary if enough variety is used in the diet. Providing calcium separately allows the turtle to decide when it needs more calcium.
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- Calcium Sources: Cuttlebone, plaster block, boiled and crushed eggshells, and crushed oystershell can provide calcium on demand.
- Vitamin D3: Dietary calcium is not properly utilized in the absence of vitamin D3. Turtles can manufacture D3 if provided access to UV-B rays from direct sunlight or a good reptile light (e.g. Reptisun or Reptile D-Light.) Or D3 can be provided in the diet through supplements like Rep-Cal.
Foods to Avoid or Limit
- High-Protein Foods: Excessive amounts of meat intended for human consumption and other high-protein food sources such as cat food or dog food can put abnormal stress on the kidneys and may be implicated in some shell deformities. When used sparingly as part of a varied diet, no harm is likely to result, but high protein meats should not be used as a staple.
- Milk Products: Reptiles do not utilize milk products at any stage of their lives and lack the enzymes to break down lactose.
- Processed Foods: Canned and other processed foods are often very high in salt and other preservatives. The effects of these things are not fully known, but they would not be part of a natural diet.
- Toxic Plants: Although some turtles are known to eat poisonous plants in the wild, the specifics of that practice are not well studied. It is probably wisest to avoid the use of toxic plants in their habitats
The Importance of Variety and Moderation
Rather than avoiding perfectly fine, nutritious foods such as spinach or broccoli, we should use everything in moderation. Turtles in the wild pay no attention to lists of “good” foods and “bad” foods. They avoid difficulties that could arise from some of the so-called bad foods by eating them sparingly, as part of a great natural variety around them. When they feel the need for calcium, they seek out eggs from amphibians & birds, or gnaw on carrion bones, or even eat mineral-rich dirt and sand. When humans intervene in the lives of wild animals, they tend to over-analyze things, to the detriment of the animals. By avoiding foods on the “bad” lists, we cheat our animals of many nutritious menu items. For instance, cabbage is often forbidden because of the high goitrogen content. If you fed your turtle nothing but cabbage, and never let it have iodine in any other form, the turtle could indeed develop kidney problems and goiter. So just use cabbage as one of the many item on the menu, and provide cuttlebone for the iodine replacement.
If you feed just cantaloupe and crickets, there will be problems down the line. There’s nothing wrong with those foods. They’re simply insufficient. If you feed a wide variety of foods, the occasional use of cabbage, cooked beef heart or lettuce will not cause problems. Further, feeding some foods that are low calcium foods, or high in phosphorous or oxalates, will matter not at all if a separate source of calcium (cuttlebones/ plasterblocks/ eggshells/ crushed oystershell) is always available. This is more in keeping with the way turtles feed in the wild anyway. While some keepers carefully consider the calcium/phosphorus ratio, turtles don’t waste a precious second pondering the chemical analysis of their food. If it’s tasty and it’s there, they’ll eat it! Later, they’ll munch some carrion bones or birds’ eggshells and get caught up on calcium. It may be impossible for us to really “think like a turtle” but we can at least try.
Feeding Frequency and Amount
Be careful not to overfeed your Cooter. I recommend only feeding 2 to 3 times a week for adult turtles and every day or every other day for the rapidly growing hatchlings. Adult Pseudemys are very vegetarian by nature and will consume vegetables, greens such as mustard greens, turnip greens, dandelion, spinach, carrots, zucchini and any aquatic vegetation, i.e. duckweed, water lettuce, water hyacinth, etc. While it is a much more minor part of their diet, they will also consume insects, worms and crayfish. In hatchlings this protein hunger is more apparent but they are still primarily herbivorous. I would add that the amount to feed should be what would fit inside the head, minus the neck. You can split this amount into two parts if you want to feed twice a day for hatchlings, or each day for adults.
Captive Environment
In captivity, cooters need an aquatic habitat, with a dry basking area. They need a warming light and UVB radiation (from reptile lights or direct sunshine). River cooters enjoy basking on logs or sun-warmed rocks, and are frequently found in the company of other aquatic basking turtles (sliders and painteds) sometimes piled up on top of each other. All are quick to slip into the water if disturbed. Diurnal by nature, these turtles wake with the warming sun to bask and forage. They can move with surprising speed in the water and on land. It is not unusual for them to wander from one body of fresh water to another, but many seem to develop fairly large home ranges, which they seldom or never leave. They sleep in the water, hidden under vegetation. While those that live in areas that are quite warm remain active all winter, river cooters in cooler climes can become dormant during the winter for up to two months, in the mud, underwater. They do not breathe during this time of low metabolism, but can utilize oxygen from the water, which they take in through the cloaca.
For 1 to 3 babies, a 10-20 gallon aquarium works for the first year with a water level about the height of your index finger. It is recommended to upgrade tank size to 10 gallons per turtle. A single adult turtle would require at least a 100 gallon aquarium, but can also be housed in a kiddie pool or stock tank. Internal or canister filters can be used to properly filtrate water with bi-weekly water changes. It is also recommended to run a filter rated above the gallons of the tank as turtles are known to make quite a mess. Some species of cooter are more cold tolerant than others, and if your climate allows it, housing cooters outdoors proves to be much more practical given proper enclosure and safety parameters are met. Turtles require a basking area where they can completely dry out and bask under heat and UVB (keep basking temperatures at around 90-95). Turtles are not picky, so anything from bricks, wood, or a turtle dock works for them. Water temperature can remain at ambient room temperature, about 76-80 degrees. All lights should be kept on a day/night cycle.
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Conservation Status and Threats
According to IUCN, the River cooter is locally common and widespread throughout its range, but no overall population estimate is available. The species faces several threats, including:
- Habitat Loss: Habitat loss and degradation from development and agriculture affect all cooter species.
- Predation: Raccoons, opossums, red foxes, river otters, feral hogs, dogs, black bears, alligators, and birds of prey are all threats to cooters, but the impacts of native predators to cooter populations is minimal. Nonnative predators, such as Argentine black and white tegus or red imported fire ants, prey on eggs and hatchlings of cooters and may be a more significant threat than native predators.
- Vehicle Impacts: Motorized boats may be a significant source of mortality in highly trafficked areas. Cooters are also vulnerable to car strikes when crossing highways or roads during the nesting season.
- Collection from the Wild: Under F.A.C. 68A-25.002(6), no person can take a cooter species, their eggs, or parts there of, from the wild.