The terms "turtle" and "terrapin" are sometimes used interchangeably but actually refers to two different types of animals. Both turtles and terrapins have hard shells, scales, are cold blooded, lay eggs and belong to the Chelonia taxonomic order. While turtles and terrapins are very similar, terrapins are a species of turtle that lives in and uses a different habitat. The diamondback terrapin and river terrapin are two types of terrapins.
The main distinguishing feature of terrapins is their habitat. While turtles can live in either fresh or seawater, terrapins are found in salty swamp areas where the water is salty but less so than seawater. Terrapins spend time on both land and water. In contrast, turtles spend most of their lives in the water and tortoises live on land.
The diamondback terrapin is the only terrapin found in the United States. Diamondback terrapins are usually smaller than other turtles and their name reflects their size. The name "terrapin" is derived from an Algonquian Indian word "torope," which means "little turtle." However, while diamondback terrapins are small, the river terrapin in Southeast Asia can be bigger than a human child.
The diamondback terrapin is named after the diamond-shaped markings on its shell. Their top shell can be medium grey, brown or black, while its skin can range from light grey to black. Their bottom shell can be yellow, green or black and may have dark splotches. Adult female diamondback terrapins range from 6 to 9 inches while males range from 4 to 6 inches. The diamondback terrapin is found along the Eastern and Southern United States' coast, from Massachusetts all the way down to Texas. Their diet includes small hard-shell prey, such as snails and crabs, fish and plants.
The river terrapin is a critically endangered species found in Southeast Asia. River terrapins are large animals. Adult females, which are bigger than adult males, can have a shell length of 24 inches and weigh up to 34.9kg. They have an upturned snout and four front claws. Another distinguishing feature is the hard shelf, a secondary palate, in their upper jaw. This secondary palate help crush their food, which consists mostly of fruits and plants.