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Tortoise

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Tortoise

Tortoises are a family, Testudinidae. Testudinidae is a Family under the order Testudines and suborder Cryptodira. There are fourteen extant families of the order Testudines, an order of reptile commonly known as turtles, tortoises, and terrapins.

The suborder Cryptodira is a suborder of Testudines that includes most living tortoises and turtles. Cryptodira differ from Pluerodia in that they lower their necks and pull the heads straight back into the shells, instead of folding their necks sideways along the body under the shells’ marginals.The testudines are some of the most ancient reptiles alive. Tortoises are shielded from predators by a shell.

The top part of the shell is the carapace, the underside is the plastron, and the two are connected by the bridge. The carapace is fused to both the vertebrae and ribcage, and tortoises are unique among vertebrates in that the pectoral and pelvic girdles are inside the ribcage rather than outside. Tortoises can vary in size from a few centimeters to two meters.

Scientific classification

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Reptilia
  • Order: Testudines
  • Suborder: Cryptodira
  • Superfamily: Testudinoidea
  • Family: Testudinidae
  • Type species: Testudo graeca

Tortoise, any member of the turtle family Testudinidae. Formerly, the term tortoise was used to refer to any terrestrial turtle.

The testudinids are easily recognized because all share a unique hind-limb anatomy made up of elephantine (or cylindrical) hind limbs and hind feet each digit in their forefeet and hind feet contains two or fewer phalanges.

With the exception of the pancake tortoise (Malacochersus tornieri), the shell is high domed. Shells of some species are nearly spherical with a flattened base.

Facts

  • A tortoise is a turtle, but a turtle isn’t a tortoise.
  • A group of tortoises is called a creep.
  • Tortoises inspired the ancient Roman military.
  • Tortoises have an exoskeleton AND an endoskeleton.
  • The scales on the carapace are called scutes.
  • The lighter the shell, the warmer the origin

Diet

Most land based tortoises are herbivores, feeding on grazing grasses, weeds, leafy greens, flowers and certain fruits. Their main diet consists of alfalfa, clover, dandelions and leafy weeds.

Lifecycle

Most species of tortoises lay small clutch sizes, seldom exceeding 20 eggs, and many species have clutch sizes of only 1-2 eggs. Incubation is characteristically long in most species, the average incubation period are between 100 and 160 days. Egg-laying typically occurs at night, after which the mother tortoise covers her clutch with sand, soil, and organic material. The eggs are left unattended, and depending on the species, take from 60 to 120 days to incubate.

The size of the egg depends on the size of the mother and can be estimated by examining the width of the cloacal opening between the carapace and plastron. The plastron of a female tortoise often has a noticeable V-shaped notch below the tail which facilitates passing the eggs. Upon completion of the incubation period, a fully formed hatchling uses an egg tooth to break out of its shell. It digs to the surface of the nest and begins a life of survival on its own.

They are hatched with an embryonic egg sac which serves as a source of nutrition for the first three to seven days until they have the strength and mobility to find food. Juvenile tortoises often require a different balance of nutrients than adults, so may eat foods which a more mature tortoise would not. For example, the young of a strictly herbivorous species commonly will consume worms or insect larvae for additional protein.

History

Tortoises and Turtles have existed since the era of the dinosaurs, some 300 million years ago. Tortoises and Turtles are the only surviving branch of the even more ancient clade Anapsida, which includes groups such as the procolophonoids, millerettids and pareiasaurs. Most of the anapsids became extinct in the late Permian period, with the exception of the procolophonoids and the precursors of the testudines.

Sexual dimorphism

Many species of tortoises are sexually dimorphic, though the differences between males and females vary from species to species. In some species, males have a longer, more protruding neck plate than their female counterparts, while in others, the claws are longer on the females.

In most tortoise species, the female tends to be larger than the male. The male plastron is curved inwards to aid reproduction. The easiest way to determine the sex of a tortoise is to look at the tail. The females, as a general rule, have smaller tails, dropped down, whereas the males have much longer tails which are usually pulled up and to the side of the rear shell.

Tortoise images

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Image by congerdesign from Pixabay

Also more: Viperidae

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