Testudines
Testudines, commonly known as turtles, are an ancient and diverse order of reptiles that have a global distribution. They are characterized by their unique bony shell, which protects their internal organs and provides a framework for their limbs and muscles. Turtles have existed for over 200 million years, making them one of the oldest groups of reptiles still alive today.
Common Names
The term turtle is often used interchangeably with tortoise and terrapin, but there are subtle differences in their usage. While all three terms refer to members of the order Testudines, turtle is generally used for aquatic species, tortoise for terrestrial species, and terrapin for semi-aquatic species. However, there is no strict scientific definition for these terms, and they are often used loosely.
Characteristics
Turtles have several distinctive characteristics that set them apart from other reptiles:
- Shell: The most prominent feature of turtles is their bony shell, which is composed of a dorsal carapace and a ventral plastron. The shell is made up of bony plates, known as scutes, that are covered in keratin. The shell provides protection from predators and helps regulate body temperature.
- Teeth: Unlike most other reptiles, turtles do not have teeth. Instead, they have sharp, keratinous beaks that they use to bite and tear food.
- Limbs: Turtles have limbs that are adapted for swimming, walking, or burrowing, depending on their environment. Some aquatic turtles have webbed feet or flippers, while terrestrial turtles have strong, clawed limbs.
- Reproduction: Turtles are oviparous, meaning they lay eggs. The eggs are typically laid in nests dug in the sand or soil, and the young turtles hatch independently.
Environments
Turtles are found in a wide range of habitats, including freshwater lakes, rivers, and swamps, as well as saltwater oceans and seas. They are also found in terrestrial environments, such as forests, grasslands, and deserts. The specific environment a turtle inhabits depends on its species and its adaptations.
Marine Turtles
Marine turtles are a group of turtles that have adapted to life in the oceans. They are characterized by their streamlined bodies, flippers, and salt glands that help them remove excess salt from their bodies. Marine turtles are found in all oceans around the world, and they play an important role in marine ecosystems. Some common examples of marine turtles include the leatherback sea turtle, the green sea turtle, and the hawksbill sea turtle.
References
World Wildlife Fund: Sea Turtles
National Geographic: Turtles
The Turtle Conservancy: Information on Turtles