The Diamondback Terrapin (Malaclemys terrapin) is unique among turtles due to its adaptation to brackish waters, a mixture of salt and fresh water. This species inhabits coastal marshes, estuaries, tidal creeks, and mangroves along the eastern and southern coasts of the United States, from Cape Cod to the Gulf of Mexico. Their ability to tolerate a range of salinities is a remarkable adaptation, allowing them to live in environments that fluctuate between fresh and saltwater. One of the most striking features of the Diamondback Terrapin is its intricately patterned skin, which ranges from pale gray to black and often has speckled or lined markings, giving it a distinctive appearance. Its name comes from the diamond-shaped patterns on its carapace, which further distinguishes it from other turtle species.

Diamondback Terrapins are highly sought after in the culinary world, particularly in the 19th and early 20th centuries when they were considered a delicacy in terrapin soup. Overharvesting for food, along with habitat loss and mortality from getting trapped in crab pots, has led to a decline in terrapin populations. Conservation efforts have since been implemented to protect this species, including the use of bycatch reduction devices in crab pots to prevent accidental trapping. The terrapins are also noteworthy for their sexual dimorphism; females are significantly larger than males, reaching up to 9 inches in shell length, while males typically grow to around 5-6 inches. This size difference likely helps females produce and carry larger clutches of eggs, ensuring better reproductive success in their fluctuating coastal habitats.