The diamondback terrapin ( Malaclemys terrapin) is an iconic turtle species native to the Northeastern and southern United States, and Bermuda. It is the only exclusively estuarine turtle species in North America. The name "terrapin" originates from the Algonquian word "torope," used by early European settlers to describe turtles inhabiting brackish waters, neither entirely fresh nor marine. These turtles have one of the largest ranges of all turtles in North America, stretching as far south as the Florida Keys and as far north as Cape Cod.
Diamondback Terrapin Characteristics
Diamondback terrapins get their common name from the diamond pattern on their carapace (top shell). The shell is usually wider at the back than in the front, and from above it appears wedge-shaped. The shell coloring can vary from brown to grey, and their body color can be grey, brown, yellow, or white. All have a unique pattern of wiggly, black markings or spots on their body and head. Female terrapins are larger than males and average around 6-9 inches long while males average between 4.5-5 inches in length. The carapace (upper shell) can be gray, brown, yellowish green, or nearly black, and has brown concentric circles alternating with gray, black, or yellow. The plastron (lower shell) is yellowish to greenish, and often has an irregular pattern of black flecks; it may have a dark brown blotch in each scute and the margins of the scutes may be outlined with thin black lines. The skin varies in shade from white to black, but is usually gray with an irregular pattern of small to large darker colored flecks.
Natural Habitat and Behavior
Diamondback terrapins live in the very narrow strip of brackish coastal waters on the Atlantic and Gulf coasts of the United States, from as far north as Cape Cod, Massachusetts, to the southern tip of Florida and around the Gulf Coast to Texas. A small breeding subpopulation is also found in the Bermuda Islands. In most of their range terrapins live in Spartina marshes that are flooded at high tide, but in Florida, they also live in mangrove swamps. Other habitats include estuaries, lagoons, and tidal creeks. Diamondback terrapins are social creatures and are often seen basking together during the day. At night they rest in their burrows in the mud at low tide. These turtles spend the majority of their life in water, however, they do leave the water to bask and lay eggs.
Diet in the Wild
Diamondback terrapins are carnivores. They have strong jaws for crushing shells of prey, such as clams and snails. Diamondback terrapins eat a variety of foods including snails, crabs, clams, mussels, worms, fish and plants. The diamond-backed terrapin is considered a keystone species due to its role as a predator of herbivorous invertebrates such as crabs and snails in salt marsh ecosystems across the east coast of the United States.
Diet in Captivity
As carnivores most Diamondback Terrapins will readily accept any number of commercial turtle diets. Captive-produced Diamondback Terrapins are hardy and readily accept a variety of commercial diets and live foods. We suggest a mixture of three or four different high-quality types. Fish, frozen crayfish or shrimp, and earthworms should add to the variety. In captivity, you can feed them a mix of turtle pellets, dried shrimp, and other seafood once a day, every other day. Food and treats that will float in their tank can be stimulating for them, such as Zilla River Shrimp, Turtle Chasers, or Zilla Turtle Sticks for a well-rounded diet. They are messy eaters, so be ready to clean promptly once they are finished eating to avoid bacteria and other buildup.
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Nutritional Needs and Supplementation
When keeping Diamondback Terrapins in captivity, it's crucial to provide a diet that meets their nutritional needs. This includes pellets that are high in vitamins A and E and that contain D3. Supplementing their diet with calcium is also important for maintaining shell health and preventing metabolic bone disease.
Captive Care Considerations
Young, captive-hatched Diamondback Terrapins thrive in captivity as long as their enclosures are thoughtfully prepared. They enjoy clean, filtered, and aerated water with a neutral to slightly acidic pH. Set them up in a 20-gallon long aquarium similar to a Slider enclosure and give them plenty of basking areas with hot spots of 90° F (32° C) and offer them live plants and a variety of commercial diets and live foods. Good water quality, provided by proper filtration, is imperative to the well-being of Diamondback Terrapins. Indoors, a basic setup in a large aquarium, tub, or stock tank will be sufficient to hold a pair or trio of adult diamondback terrapins. Add an efficient filtration system. Diamondback Terrapins are baskers, so add a shop light fixture with UVB-emitting bulbs, and at least one basking spot with a spotlight (100-watt T-Rex Active UVHeat® bulb) mounted above. Add a variety of floating and submerged aquatic plants to the terrapin enclosure. We suggest a water temperature of 76-78° F (24-26° C) and the optimal pH for captive Diamondback Terrapins seems to be in the 6.8 to 7.0 range. Therefore, many keepers add salt to their enclosures. Most keepers feel that Diamondback Terrapins raised in captivity do not require this raised salinity level, but we believe that some aquarium or marine salt helps. Salinity prohibits or greatly reduces the growth of many types of bacteria. Their tank should be deep enough to swim and dive in comfortably, with a water depth that is at least 3 times as deep as the length of their shell. Aim for a 75-gallon tank or larger, such as the Aqueon Standard Glass Terrarium. Use a good filter like the Aqueon Quietflow® Canister Filter 400 to maintain water quality and prevent unfavorable skin and shell conditions. Water care products like Zilla Water Conditioner, Zilla Miracle Ball, and Zilla PURE help maintain safe and healthy water while significantly reducing time spent on upkeep. Turtles need to bask in order to warm up and regulate their metabolism. Provide a dry, warm basking surface like a rock or accessories such as the Zilla Freestanding Floating Basking Platform or Zilla Basking Platform Ramp. For substrate, crushed coral is recommended as diamondback terrapins like to bite at the coral. Maintain water temperature for diamondback terrapins around 70˚F. During the day, use heating lights such as the Zilla Canopy Series Fluorescent UVB/UVA Bulbs inside a Zilla Premium Reflector Dome to project adequate heat.
Water Quality
Good water quality, provided by proper filtration, is imperative to the well-being of Diamondback Terrapins. If kept in poor water conditions, with sub-optimal diets, Diamondback Terrapins will often show a range of shell problems including "warping", soft shell disease, and fungal infections. In extreme cases, they will die. Poor water quality often leads to eye problems in these turtles. To reduce the growth of many types of bacteria, you can add one tablespoon of aquarium or marine salt per gallon of water.
Potential Health Issues
If kept in poor water conditions with a sub-optimal diet, Diamondback Terrapins will often show a range of shell problems including "warping", soft shell disease, and fungal infections. Therefore, always reduce your likelihood of problems by not crowding Diamondback Terrapins and offer them plenty of clean, aerated water.
Conservation Status and Threats
According to the IUCN Red List, the total population size of the Diamondback terrapin is unknown. However, there is an estimated population of the species consisting of 100 individuals in the Bermuda Islands. The major threats to these turtles are all associated with humans. People tend to build their cities on ocean coasts near the mouths of large rivers and in doing so they have destroyed many of the huge marshes that terrapins inhabited. Traps used to catch crabs, both commercially and privately, have commonly caught and drowned many Diamondback terrapins, which can result in male-biased populations, local population declines, and even extinctions. When these traps are lost or abandoned (“ghost traps”), they can kill terrapins for many years. Nests, hatchlings, and sometimes adults are commonly eaten by raccoons, foxes, rats, and many species of birds, especially crows, and gulls. The density of these predators are often increased because of their association with humans. Terrapins are also killed by cars when nesting females cross roads and mortality can be high enough to seriously impact populations. These turtles are still harvested for food in some states. Terrapins also suffer from pollutants such as metals and organic compounds and are collected for the pet trade. Some people breed the species in captivity and some color variants are considered especially desirable.
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Conservation Efforts
Beginning in March 2023, all recreational blue crab traps will be required to have a rigid funnel opening no larger than 2 x 6 inches at the narrowest point, or a 2 x 6-inch bycatch reduction device. If you come across an injured diamondback terrapin, contact your FWC Regional Office to find a list of rehabbers in your area.
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