There are several species of turtles that can have black coloration. Black coloration provides camouflage and protection from predators in aquatic habitats. The most common black turtle species include the Eastern Painted Turtle, Spotted Turtle, Bog Turtle, and Common Musk Turtle. The coloration can range from completely black shells to black spots, streaks or patches on the shell, skin, or legs. In this article, we will discuss some of the most common types of black turtles, their key identification features, habitat, and distribution.
Eastern Painted Turtle
The Eastern Painted Turtle is one of the most widespread and well-known turtle species in North America. They are characterized by a smooth, low-domed, dark green to black carapace with a red marginal border along the seams of the shell scutes. The plastron is typically yellow with dark, irregular blotches. One of the key identifying features of Painted Turtles is the bright yellow stripes on their legs, neck, tail, and head.
While the typical coloration has green and yellow markings, melanistic (all black) individuals can occur. Melanistic Painted Turtles will be completely black with little to no green or yellow patterns visible. The red marginal border may still be faintly visible on some individuals.
Painted Turtles inhabit slow-moving freshwater habitats like marshes, ponds, lakes, and streams. They prefer areas with soft, muddy bottoms and abundant aquatic vegetation. Painted Turtles are found throughout eastern and central North America, from southern Canada to the Gulf Coast and from the Atlantic coast to the Rocky Mountains.
Spotted Turtle
The Spotted Turtle is a small, semi-aquatic species that reaches only 3-5 inches in length. Their most distinctive feature is the yellow or orange spots that dot their head, legs, tail, and shell. The spots usually occur on a black background color.
The carapace of Spotted Turtles is dark black or brown and smooth with low ridges. The plastron is black or brown with yellow/orange blotches in the center of each scute. Melanistic individuals may sometimes lack the bright yellow spots and appear solid black.
Spotted Turtles prefer small wetlands like swamps, bogs, fens, marshes, and ponds. They are found mainly in the eastern United States and southeastern Canada. Spotted Turtles are classified as threatened or endangered in several states due to habitat loss.
| Species | Key Identification Features |
|---|---|
| Eastern Painted Turtle | Smooth black shell, red marginal border, yellow stripes on head/legs |
| Spotted Turtle | Black shell with yellow/orange spots, low dorsal ridge |
Bog Turtle
True to its name, the Bog Turtle inhabits boggy, marshy areas and wet meadows. They are one of North America’s smallest turtles, reaching just 3-4.5 inches in length.
The Bog Turtle has a black to mahogany-brown carapace that is highly domed with grooved, poorly defined scutes. The plastron is orange, red or yellow with black blotches in the center. Melanistic Bog Turtles may have very dark shells that appear mostly black.
Bog Turtles have a bright yellow, orange or red blotch on each side of the head behind the eyes. The throat may also have yellow patches. These are key features that can still help identify melanistic individuals.
Bog Turtles have a very limited range through the eastern United States in areas like New York, New Jersey, Pennsylvania, Maryland and Virginia. Due to severe population declines from habitat destruction, they are listed as threatened under the U.S. Endangered Species Act.
Common Musk Turtle
The Common Musk Turtle, also known as the Eastern Musk Turtle, is a small to medium-sized turtle that reaches 5-7 inches in length. They get their name from the strong musky odor they emit as a defense mechanism.
The carapace is oval-shaped and usually dark brown or black with a slightly serrated posterior margin. The plastron is yellowish with dark blotches in the centers of each scute. Melanistic forms will appear almost solid black.
Identification keys for Common Musk Turtles include a prominent ridge running down the center of the carapace, a light bar on the upper jaw, and a triangular head shape. The barbels on the chin and throat are another distinguishing feature.
Common Musk Turtles occupy quiet waters with soft substrates and abundant vegetation, like ponds, lakes, marshes and ditches. They range throughout eastern North America from southern Canada through the Midwest and Eastern U.S. to the Gulf of Mexico.
| Species | Key Identification Features |
|---|---|
| Bog Turtle | Highly domed black shell, yellow/orange head patches |
| Common Musk Turtle | Dark shell with central keel, chin barbels |
Causes of Black Coloration in Turtles
There are two primary causes of black coloration in turtles – genetic pigmentation and environmental staining.
Melanin is the dark black pigment that leads to genetic black patterning in turtle shells, skin and other tissue. The amount of melanin present during development determines the degree of black versus normal coloration in the turtle.
Some turtles, like Painted Turtles, Bog Turtles and Spotted Turtles normally have black pigmentation as part of their natural color patterns. In other species, all-black melanistic individuals occur sporadically due to genetic mutations resulting in excess melanin production.
The other cause of blackening is environmental staining from mud, leaves, acids or decaying matter in the water or substrates. This usually leads to mottled darker patches rather than uniform black coloration.
Turtle Shell Anatomy
The upper shell of a turtle is called the carapace, while the lower shell is called the plastron. Both are made up of bony structures covered in keratinous scutes.
The carapace consists of the central vertebral scutes directly connected to the turtle’s backbone and ribs. Lateral to these are the costal scutes. At the outer edge of the carapace are marginal scutes which form the rim of the shell.
The plastron usually consists of 12 scutes in most species. The central seam where the upper and lower shell join together is called the bridge.
The shells are attached directly to the turtle’s ribcage and spine. Thin layers of skin, muscle and nerves cover the bony plates and scutes, allowing the turtle some sensation and flexibility of the shell.
| Carapace Scutes | Plastron Scutes |
|---|---|
| Vertebral | Gular |
| Costal | Humeral |
| Marginal | Pectoral |
| Abdominal | |
| Femoral | |
| Anal |
Turtle Shell Color Patterns
Turtles exhibit diverse shell color patterns that can aid in species identification. Common color patterns include:
- Solid black – Entire shell is black with little to no other color visible.
- Black with red/yellow/orange markings – Black background with brightly colored markings along seams or borders.
- Spotted – Black background with yellow, orange or white spots scattered across shell.
- Streaked – Irregular black streaks and brush strokes on a lighter colored shell.
- Mottled – Splotchy patches of black over a lighter main shell color.
- Partial melanism – Portions of the shell or body are black, while other areas retain normal coloration.
The head, legs, tail, and skin can also exhibit similar black, spotted, striped or mottled color patterns.
These shell patterns are useful in species identification when used in conjunction with other diagnostic features like shell shape, scale patterns, size and body proportions.
Rare All-Black Turtle Species
While many turtles display some black patterning, all-black individuals are quite rare in most species. Some exceptions where all-black coloration is more normal include:
- Matamata – This bizarre, prehistoric-looking South American species is mostly black with a knobby, craggy carapace.
- Black pond turtle – This endangered Asian turtle has a smooth, flat black shell and head.
- Magdalena river turtle – Native to Colombia, this species has an unusual flattened skull and smooth black shell.
There are also a number of recently discovered black softshell turtle species in Southeast Asia, such as the Black Marsh Turtle and Black Softshell Turtle.
While not completely melanistic, the bright markings on the Matamata and Magdalena River Turtle shells stand out dramatically against the dark background.
Conclusion
In summary, black coloration in turtles can result from natural pigmentation or environmental staining. Some of the most common black turtle species in North America include Eastern Painted Turtles, Spotted Turtles, Bog Turtles, and Common Musk Turtles. Key identification features like shell shape, scale patterns, and body markings can help distinguish black turtle species. While not common, all-black individuals can occur in many turtle species due to excess melanin production. With over 300 turtle species globally, there is a wide diversity of shell patterns and colorations, including some that are all or mostly black. Proper identification requires looking at multiple anatomical and diagnostic features beyond just color.
