Turtles

Turtles

Description

Turtles (order Testudines) are reptiles instantly recognisable by their bony shell, which is fused to the spine and ribs and covered in horny plates called scutes. They range enormously in size, from tiny species with a shell of only about 8-10 cm to the giant leatherback sea turtle, which can exceed 2 m in shell length and weigh over 500 kg. All turtles have a toothless, keratinised beak instead of teeth.

Habitat

Turtles are found on nearly every continent and across the world's oceans, absent only from the coldest polar and high-mountain regions. The group includes land-dwelling tortoises, freshwater terrapins that live in ponds, rivers and marshes, and fully marine sea turtles that roam the open ocean.

Diet

As a group turtles are opportunistic omnivores, though the balance varies by species: most land tortoises are largely herbivorous, feeding on grasses, leaves and fruit, while many aquatic turtles are more carnivorous, taking fish, insects, worms, snails and other small animals.

Reproduction

All turtles reproduce by laying eggs on land, digging a nest into soil or sand. Clutch size ranges from a single egg to over 100 depending on the species, and incubation lasts from about two months in temperate species to a year in some tropical ones. In many species the temperature of the nest determines whether the hatchlings are male or female.

Lifespan

Turtles are among the longest-lived vertebrates. Many species live for several decades, and giant tortoises are famous for reaching well over 100 years; the Seychelles giant tortoise Jonathan is thought to be over 190 years old.

Did you know?

A turtle's shell is not a separate house it can climb out of, it is part of its skeleton, with the backbone and ribs fused directly into the shell. Turtles are also an ancient lineage that has existed for more than 200 million years, predating the dinosaurs' extinction by a wide margin.