Turtles and tortoises – long-lived reptiles
Turtles first appeared on Earth about 255 million years ago
Turtles are one of the most long-lived creatures in the world – some species may live for over 200 years. The Testudines order is divided into 2 subgroups, 14 families and involves 327 species and 124 subspecies.
- Kingdom: Animalia
- Phylum: Chordata
- Class: Reptilia
- Clade: Testudinata
- Order: Testudines
Turtles or tortoises?
The term turtle may be understood differently in different parts of the world. For example, in North America the word turtle is a common expression for both aquatic and terrestrial Testudines reptiles. However, in British English turtle refers only to the sea-dwelling species, as opposed to tortoises, which is typically a term for terrestrial species, that are not bound to water in terms of their habitats. Technically speaking, tortoises belong to the Testudinidae family, one of 14 extant families in their order.
To make matters even more complicated, there is also the term terrapin – in general usage it refers to small turtles that live in fresh or brackish waters, yet they do not form a separate taxonomic unit.
Areas of occurrence
Turtles live on almost every continent, apart from the Antarctic, mostly in warm seas and oceans. A vast majority of turtle species is herbivorous.
These reptiles are famous for their longevity, slow manner of movement and a carapace which is built of horny skin tissue. It may have various shapes depending on the species, however it always serves the same purpose – it protects the vulnerable turtle body from external attacks. While in danger, turtles hide their legs and head inside the shell almost completely, which is often a sufficient reason for the opponent to let go. The turtles, thanks to their carapaces, are believed to be best shelled and best protected creatures among modern animals. Moreover they have massively built legs equipped with clawed toes.
Probably the most famous tortoise species is the Galapagos giant tortoise. As recently as 200 years ago the waters surrounding these beautiful islands were densely populated by these famous giants. Today – as a result of human activity – it is an endangered species.
The largest turtles ever to live on Earth
As for today, the largest found turtle remains belong to the Late Cretaceous Archelon sea turtle from North America, which has a skeleton about 4.5 meters (14.8 ft) long. The forelimbs’ spread was about 5.25 meters (17ft 3in) wide, with body weight estimated to be over 2.2 tons (4,850 lb). A Pliocene freshwater Stupendemys turtle belonging to the Pelomedusidae family is only slightly smaller. Its remains were unearthed in Venezuela. It inhabited the South American rivers 3 million years ago and could measure up to 3 meters (9ft 10in) and weigh around 2 tons (4,400 lb).
Turtles – interesting facts
- Turtles are the only vertebrates in the world with an external skeleton.
- Turtles are cold-blooded.
- According to reliable data the Galapagos giant tortoises and Aldabra giant tortoises may live for 200+ years.
- The largest species is the nearly extinct leatherback sea turtle. It may reach even 2 meters (6ft 7in) of length and weigh over 1 ton (2,200 lb).
- The rapidity of turtle actions depends on the ambient temperature: heat makes them lazy, while they move quite fast in the cold.
- Water turtle species have transformed their legs into flat paddles.
- Tortoises move on land with a maximum velocity of 3 km/h (1.9 mph).
- Turtles do not have teeth, yet they have a sharp horny lath at the edge of their jaws.
- May 23rd is the World Turtle Day.
A tortoise in a film frame
A short footage presenting one of the most rare turtle species in the world – Burmese star tortoise (Geochelone platynota) below: