Main Difference – Turtle vs Tortoise
Turtles and tortoises are two groups of reptiles belonging to the order Testudines (Chelonia). Chelonians are commonly known as shelled-reptiles due to the presence of a bony shell, which is very prominent and easily recognized among other reptile groups. This group includes all species of turtles, tortoises, and terrapins. Chelonians are the oldest living reptiles; they appeared on the earth about 260 million years ago in Permian era. There are about 300 species of chelonians; they are all characterized by the presence of a bony box-like shell, a keratinized beak instead of teeth, unique limbs and limb girdles placed inside their ribs. The chelonian shell is not an exoskeleton but a modified part of the vertebral column. There are two parts of the shell: the domed upper shell known as the carapace, and flat lower shell known as the plastron. The carapace is composed of interlocking bony plates arisen from parts of vertebrae, ribs, and bones in the dermis. The plastron is composed of interlocking bony plates arisen from bones of the pectoral girdle and dermal bone. The carapace consists of a larger number of bony plates than those of plastron. Many species of chelonians are found in North America and South Asia. Many species are semi-aquatic, and some are strictly terrestrial. Turtles and tortoises share many similar features, hence, the whole group is sometimes referred to as turtles. The main difference between turtle and tortoise is their living habitat. Turtles are usually associated with fresh or salt-water habitats whereas tortoises are fully terrestrial. More details of turtle and tortoise will be discussed in this article.
Turtle – Facts, Characteristics, Behavior
The whole species in order Chelonia is sometimes referred to as turtles. However, in this context, we consider the amphibious aquatic chelonians as turtles. There are two types of turtles: freshwater turtles and sea turtles. Freshwater turtles have a low carapace and paddle-like legs with webbed toes that help them to swim in water. Some common freshwater turtles are red-eared turtle and painted turtle. Mud and musk turtle and snapping turtle have a reduced plastron, not streamlined bodies; this enables them to crawl along the river bottoms. Sea turtles are totally aquatic and distributed in all oceans except the Arctic Ocean. Female sea turtles come to land only to lay eggs. They have flattened shells to reduce the resistant while swimming. Their limbs have become flat flippers with no toes. The leatherback is the largest sea turtle with 6-7 feet long shells and weighing more than 660 kg. Leatherbacks do not possess a hard shell. Sea turtles are considered as an endangered group of reptiles due to rapid destruction for meat, shells, and eggs.
Tortoise – Facts, Characteristics, Behavior
Tortoises are strictly terrestrial chelonians and often called box turtles. Their feet are similar to elephant feet and they do not have webbed feet. Due to the presence of flexible areas on the plastron, they can pull their head, limbs and tail inside the shell, which provide protection from attacks by predators. Some smaller tortoises like gopher tortoises and Bolson tortoises have flattened legs and reduced-carapace that enable them to burrow. Galapagos tortoises are the largest varieties. An adult tortoises can reach 1.2 m long and weigh over 300 kg. It is found that some Galapagos tortoises have lived about 200 years.
Difference Between Turtle and Tortoise
Turtles are amphibious aquatic or fully aquatic.
Tortoises are strictly terrestrial.
Shape of the Shell
Turtles have flatted, streamlined shells.
Tortoises have dome-shaped shells, which are less streamlined.
Weight of the shell
Turtles have light-weight shells.
Tortoises have heavier shells.
Turtles have broad flipper-like legs with webbed feet.
Tortoises have short sturdy legs without webbed feet.
Turtles are usually omnivores.
Tortoises are generally herbivores.
Tortoises have usually a higher life span than turtles.
Turtles have a shorter life span.
Turtles cannot pull their head, limbs and tail inside the shell as a defensive action.
Tortoises can pull head, limbs and tail inside the shell as a defensive action due to the presence of flexible areas on the plastron.
Red-eared turtle, painted turtle, leatherback, green turtle, loggerhead turtle etc. are some examples of turtles.
Gopher tortoise, Bolson tortoise etc. are some examples of tortoises.
“Sea turtle” by Brocken Inaglory – Own work (GFDL) via Commons Wikimedia