Diamondback terrapin

The diamondback terrapin, known scientifically as Malaclemys terrapin, is a unique turtle species. It lives in brackish coastal tidal marshes. Brackish water is a mix of fresh water and salt water. This species is native to the East Coast of the United States. It also lives along the Gulf of Mexico and in Bermuda. It has one of the largest ranges of any North American turtle. This range stretches from Cape Cod in the north to the Florida Keys in the south.

The name "terrapin" comes from an Algonquian word. Early European settlers used this name for turtles in brackish water. They used it because these turtles lived neither in the sea nor in fresh water. In American English, the name still refers specifically to this species. However, in British English, the term might describe other semi-aquatic turtles like the red-eared slider. The common name comes from the diamond pattern on the carapace. The carapace is the top part of the turtle's shell.

These turtles have several biological adaptations for life in salty environments. Their skin is largely impermeable to salt, meaning salt cannot easily pass through it. They also possess lachrymal salt glands. These glands help the turtle manage salt, especially when it is dehydrated. Terrapins can also tell the difference between water with different levels of salt. They use clever behaviors to find fresh water. They might drink the fresh layer of water that sits on top of salt water after rain. They may also raise their heads to catch falling raindrops in their mouths.

Diamondback terrapins show sexual dimorphism, which means males and females look different. Females are generally larger than males. An average male has a carapace length of about 125 millimeters. An average female has a carapace length of about 175 millimeters. Some females can grow even larger. The largest female on record was over 200 millimeters long. Females also have larger, more muscular jaws than males. This helps them crush the hard shells of prey like clams and snails.

There are seven recognized subspecies of the diamondback terrapin. These include the Carolina diamondback terrapin and the Texas diamondback terrapin. Other types include the ornate, Mississippi, mangrove, and East Florida subspecies. There is also the northern diamondback terrapin. The population in Bermuda is also closely related to the Carolina population. In the wild, these turtles typically live for about 25 years. In captivity, they can live for up to 40 years.

The life cycle of the terrapin involves specific seasonal steps. They mate in the early spring. Females lay clutches of 4 to 22 eggs in sand dunes during the early summer. The sex of the hatchlings depends on the incubation temperature. This process is called temperature-dependent sex determination. Eggs usually hatch in 60 to 85 days. Hatchlings emerge in late summer or early fall. Some hatchlings may stay in their nests to overwinter. Raccoons are a major threat because they often eat the eggs in the nests.

Terrapins face many modern challenges to their survival. In the early 1900s, they were hunted almost to extinction because they were considered a delicacy. Today, they often drown in recreational crab traps. In New Jersey alone, an estimated 14,000 to 15,000 terrapins drown in these traps every year. They can also be injured by motorboat propellers. Building seawalls and bulkheads can also destroy their nesting habitats. Because of these risks, many states list them as endangered or threatened species.