Map turtles have garnered a dedicated following within the turtle hobby, captivating enthusiasts with their secretive nature and intricate patterns. These North American turtles, often found in clear, fast-flowing rivers, demand specific care in captivity. This article delves into the dietary needs of the Northern Map Turtle, providing a comprehensive guide for keepers.
Introduction to Northern Map Turtles
Northern Map Turtles ( Graptemys geographica ) are medium-sized aquatic turtles characterized by a low ridge or dorsal keel along their carapace (upper shell). The carapace, typically brown or olive brown, exhibits a netlike pattern of fine, squiggly, yellow lines reminiscent of a road map, hence their name. The hind edge of the carapace is strongly serrated (saw-toothed). Their lower shell (plastron) is light yellow with dark brown seams between the scutes (shell scales). The head, limbs, and tail are dark brown to nearly black, adorned with numerous narrow, greenish-yellow lines. These turtles are strong swimmers with fully webbed limbs.
Sexual dimorphism is prominent in map turtles, with females reaching much larger adult sizes than males. Adult females also have much larger heads than males. While males reach approximately 4 to 6 inches in Straight Carapace Length (SCL), females can grow to 7 to 10 3/4 inches. Males also have elongated claws used in courtship displays, a more oval carapace with a more distinct keel, and a longer, thicker tail. The male's vent opens beyond the edge of the carapace, while the female's opens within the carapace.
Natural Diet and Adaptations
Northern Map Turtles are omnivores. In their natural habitat, their diet consists of snails, clams, insects (especially mollusks, fish, caddis flies, mayflies, damselflies, and some plant matter). Adult females, possessing large, muscular jaws, consume hard-shelled snails and crayfish. The False Map Turtle ( Graptemys pseudogeographica ) has a diet almost entirely of insects and insect larvae instead of crustaceans and mollusks seen in other map turtles.
Feeding Northern Map Turtles in Captivity
In captivity, the majority of the Northern Map Turtle's diet should consist of commercial floating aquatic turtle food and a variety of aquatic plants. Hatchlings and young map turtles typically consume more plant matter than adults. It's important to provide a low-volume, well-rounded diet.
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Commercial Turtle Food
A good quality commercial pellet should contain D3, calcium, vitamin A, and Vitamin E. As hatchlings grow most during their first year, they can eat pellets that are higher in protein until they reach about 3 inches SCL. When they reach about 2 1/2 inch -3 inch SCL, switch to a pellet that is lower in protein and feed the pellets only every other day.
Plant Matter
Offer a variety of aquatic plants, such as:
- Lettuce
- Kale
- Escarole
- Mustard Greens
- Dandelions
- Romaine, red or green leaf lettuce
- Carrots
- Dandelion greens
These provide essential vitamins and minerals.
Treats
Freeze-dried shrimp and krill can be given as occasional treats. However, avoid overfeeding protein-rich foods like worms, crickets, shrimp, chicken, and eggs, as excessive protein can lead to rapid growth, shell issues (such as pyramiding), obesity, and organ problems. Limit these treats to once a week.
Feeding Schedule and Quantity
Feed hatchlings once daily. The amount of pellets should be either:
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- The amount of pellets that would fit inside its head as if it were hollow.
- As many pellets as he/she will eat in 5 to 10 minutes until his voracious appetite seems to subside a bit…then scoop out the excess.
Adjust the quantity based on the turtle's growth, activity level, and appetite. As they grow, switch to feeding every other day. Offer vegetables daily for grazing.
Additional Considerations
- Vitamin D3: While a good quality pellet provides D3, supplementing with a UVB bulb is recommended for extra D3, which is needed for a healthy shell.
- Calcium: Provide a calcium supplement, such as cuttlebone (sold for birds), which also helps keep the turtle's beak in good shape. A calcium to phosphorus ratio of preferably 2 or more to 1 is important. Insufficient Vit.
- Avoidance of Harmful Foods: Avoid feeding spinach, rhubarb, and beet greens, as they interfere with Vit.
Water Quality and its Impact on Diet
Maintaining excellent water quality is paramount for the health and well-being of Northern Map Turtles. Remember: Try to maintain a high concentration of oxygen in your Map turtle enclosure. High water quality is achieved by adding lots of extra aquatic plants and using a larger-than-expected filtration unit. Poor water quality can lead to various health problems, including shell and skin infections, which can indirectly affect their appetite and ability to process food.
Filtration and Oxygenation
Map turtles thrive in clear, fast-flowing rivers, so replicating this environment in captivity is crucial. Use an outside filter and add a small airstone to oxygenate the water. Regular water changes are essential to maintain water quality.
Substrate
The substrate can range from bare-bottom tanks (easier for cleaning) to sand, river rock, or gravel. Avoid large gravel that the turtle could swallow, potentially causing gastrointestinal (GI) issues.
Basking Area
Map turtles are avid baskers, requiring a basking spot with a temperature of mid. F.* for adults and mid. F.* for hatchlings. A basking platform that will support their weight and is non-abrasive should be provided.
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Common Health Issues Related to Diet
- Shell Problems: Map turtles are prone to shell problems in captivity, often developing a mild form of fungal infection if they don't receive natural sunlight and indoor UVB. This appears as white or gray patches on the carapace.
- Pyramiding: An improper diet, particularly one lacking in calcium and Vitamin D3, can lead to pyramiding of the shell.
- Gastrointestinal Issues: Poorly digestible foods can cause GI issues.
Breeding Considerations
Northern Map turtles can be bred in captivity. Induce breeding behavior via a 90 day hibernation or 'cool down' period. Males show interest in females by head bobbing. Eventually the female may give into his advances and allow him to mount.
To prepare for egg-laying, provide a nesting box filled with soil 12 - 14" deep. After the eggs are laid, incubate them at 78º F for 55 to 60 days.