Tortoise

Tortoises are reptiles belonging to the family Testudinidae within the order Testudines, which means "tortoise" in Latin. Like all testudines, tortoises have a special shell that helps protect them from predation and other dangers. Their shell is usually very hard, and they can pull their necks and heads right back into it for safety, a trait they share with other members of the suborder Cryptodira.

Tortoises come in many different sizes. Some, like the Galápagos giant tortoise, can grow longer than 1.2 metres (about 3.9 feet), while tiny ones such as the speckled Cape tortoise have shells just 6.8 centimetres (about 2.7 inches) long. A few types of tortoises, including the Galápagos giant tortoise and the Aldabra giant tortoise, have evolved to weigh more than 100 kilograms (about 220 pounds).

Most tortoises are active during the day, which means they are diurnal, but some may also be more active at dawn or dusk, depending on the temperature, making them crepuscular. They tend to be reclusive, meaning they like to keep to themselves. Tortoises are known for living very long lives—longer than any other land animal. While many live over 150 years, one famous Aldabra giant tortoise named Adwaita might have lived as long as 255 years! On average, tortoises can live between 80 and 150 years. Despite their slow movement, tortoises are fascinating creatures that can survive for many decades in the wild.

Terminology

Different English-speaking regions use words like "turtle," "tortoise," and "terrapin" in varying ways. In American English, "turtle" is a general term for all members of the order Testudines, while "tortoise" specifically refers to slow-moving land-dwelling species. For example, the box turtles are land-dwelling but are still called turtles, not tortoises.

In British English, "tortoise" is often used for any land-dwelling member of the order Testudines, not just those in the family Testudinidae. The term "terrapin" in Britain usually refers to small turtles living in fresh or brackish water, such as the diamondback terrapin. Australian English traditionally uses "tortoise" for freshwater turtles, even though true land tortoises are not native to Australia. Some experts there prefer the term "freshwater turtle" to avoid confusion.

Biology

Most tortoises lay small clutches of eggs, usually only one or two at a time. The eggs take a long time to hatch, often between 100 and 160 days. After the eggs are laid, the mother tortoise covers them with sand and leaves them. When the baby tortoise is ready to hatch, it uses a special tooth to break out of the egg and starts its life alone. Baby tortoises have a small sac inside them that gives them food for a few days until they can find their own.

Tortoises can live for a very long time, sometimes over 150 years. They are known for their long lives and are symbols of longevity in some cultures. The number of rings on a tortoise's shell can sometimes help guess its age, but this is not always accurate because it depends on how much food and water they have.

Distribution

Tortoises live in many places around the world, from southern North America to southern South America, around the Mediterranean basin, across Eurasia to Southeast Asia, in sub-Saharan Africa, Madagascar, and some Pacific islands. They are not found in Australasia. These tortoises can live in deserts, grasslands, scrublands, and forests, from sea level up into the mountains. Most of them prefer areas that are dry.

Some islands used to have very large tortoises. Tortoises can survive long periods without food or water, which helps them travel across oceans. Today, there are only two types of giant tortoises left: the Aldabra giant tortoise on Aldabra Atoll and the Galapagos giant tortoise on the Galapagos Islands. Sadly, many giant tortoises on other islands were lost because of human activity.

Diet

Tortoises are mainly herbivores, which means they eat plants. They enjoy eating grasses, weeds, leafy greens, flowers, and sometimes fruits. Occasionally, tortoises have been seen eating birds, and some species might eat worms, insects, or carrion in the wild. However, it’s important not to give them too much protein, as this can cause health problems like shell deformities. Each tortoise species has its own special dietary needs.

Main article: Herbivores
Further information: Worms, Insects

Behavior

Tortoises communicate differently than many other reptiles. Because of their shell and short limbs, they don’t rely much on visual signals. Instead, they use their sense of smell to figure out if another tortoise is male or female, which helps them find a mate.

They also use touch during fights and courtship. In these situations, tortoises will ram into each other to show strength or interest.

Taxonomy

This species list largely follows Turtle Taxonomy Working Group (2021) and the Turtle Extinctions Working Group (2015).

Family Testudinidae Batsch 1788 includes many types of tortoises. Some well-known kinds are the Aldabrachelys gigantea (Aldabra giant tortoise), Astrochelys radiata (radiated tortoise), Centrochelys sulcata (African spurred tortoise), and Chelonoidis niger (Galapagos giant tortoise). There are also many extinct tortoises known only from fossils, such as Aldabrachelys abrupta and Chelonoidis cubensis.

Phylogeny

Tortoises have been studied to understand their evolutionary history. Scientists have used molecules and DNA to create family trees that show how different tortoise species are related. These studies help us learn how tortoises have changed over millions of years. Recent research continues to update our understanding of their family relationships.

In human culture

Further information: Cultural depictions of turtles

See also: World Turtle

Tortoises have played important roles in many cultures. In Hinduism, Kurma was one of the forms taken by the god Vishnu. In Chinese and Japanese traditions, tortoises were thought to have special powers and their shells were used to make predictions.

Tortoises have also been part of important events. In 1968, two Russian tortoises traveled around the Moon on a spacecraft called Zond 5 and returned safely.