Aquatic turtles can be categorized into freshwater turtles, like the red-eared sliders, pig-nosed turtles, and softshell turtles, and marine turtles, like the Olive ridleys, Kemp's ridleys, hawksbill turtles, and the leatherbacks.
Fresh-water Turtle Species
Red-eared Sliders: Native to the southern United States, red-eared sliders are semi-aquatic in nature. They gets their name from the red mark around their ears. Females are bigger, measuring anywhere between 25 - 33 cm. Males, on the other hand, measure 20 - 25 cm in length.
Softshell Turtles: These turtles are found in lakes and streams. They can measure up to 2 feet. The snout-shaped bottle nose is the characteristic feature of this species. It helps them breathe properly as they can keep their nose just above the surface of the water even when their entire body is submerged.
Pig-nosed Turtle: The pig-nosed turtles are native to Australia, where they are found in lagoons, freshwater streams, and rivers. Their range spans southern New Guinea region and Northern Territory of Australia. The carapace (i.e., the upper exoskeleton or simply, the shell) of these turtles is gray in color, while their plastron is cream-colored. The species gets its name from the shape of its nose, which resembles the snout of a pig.
Marine Turtle Species
Olive Ridley: These turtles are named so because of the olive-green color of their shells. The zoological name of this species is Lepidochelys olivaceae. On an average, they weigh around 100 lbs and have a carapace length of about 76 cm. India and Costa Rica are the important nesting sites for Olive ridleys.
Kemp's Ridley: The Kemp's ridley turtle belongs to the same genus as the Olive ridley; its zoological name is Lepidochelys kempii. Average weight of this turtle species is 99 lbs, and they are known to attain a maximum length of 2 - 3 feet at full growth.
Flatback: Flatback turtles are found in the coastal areas of Papua New Guinea and inland regions of northern Australia. In northern Australia, these aquatic animals can be found in lagoons, estuaries, coral reefs, and grassy waters. Flatbacks have a low-domed carapace and thus, the name. The body length of these turtles is known to be in the range of 90 cm.
Leatherback: It is the biggest sea turtle species in the world, and weighs anywhere between 550 - 1,500 lbs. Though the average length of the leatherback species is 1.5 meters, specimen measuring 2 meters also surface once in a while. In fact, the biggest leatherback caught till date measured 3 meters. This turtle can be found in all the oceans of the world, including the region stretching from Alaska to New Zealand.
Hawksbill: The hawksbill is an endangered species of turtle. These turtles are known to attain a length of up to 1 meter at full growth and weigh around 175 lbs. Its appearance is similar to many other sea turtles. Hawksbills are called so because of their curvy and sharp beak. Interestingly, it is the only species (Eretmochelys imbricata) under the genus Eretmochelys. As for the main features of the hawksbills, they are their flipper-like limbs and depressed body shape.
Green Turtle: The green turtle is called so because of green-colored skin beneath the shell. The International Union for Conservation of Nature (IUCN) and Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) has declared the green turtle an endangered species. Average weight of adult turtles is 200 lbs, while their body length is around 1.5 meters. This turtle is found in tropical and sub-tropical waters.