Testalkatúak

Testalkatúak, or Testudines, is an order of reptiles characterized by their high-domed shells, which are used for protection. This order includes both extant (living) and extinct species, with the latter being more numerous. The order is divided into two suborders: Cryptodira, which includes most living species like turtles and tortoises, and Pleurodira, which includes the softshell turtles and the side-necked turtles.

Testalkatúak are primarily herbivorous, although some species may be omnivorous or even carnivorous. They have a unique digestive system that allows them to extract nutrients from plant material efficiently. The order is known for its diversity in size, with species ranging from the speckled padloper tortoise, one of the smallest, to the Aldabra giant tortoise, one of the largest.

Reproduction in Testalkatúak varies. Some species are oviparous, laying eggs that develop outside the mother's body, while others are ovoviviparous, retaining the eggs within their bodies until they hatch. The sex of offspring is often determined by the temperature of the nest, a phenomenon known as temperature-dependent sex determination.

Testalkatúak have a global distribution, with many species found in freshwater habitats. However, some, like the Galápagos tortoises, are adapted to arid environments. The order has faced threats due to habitat loss, pollution, and over-exploitation, leading to declines in many species. Conservation efforts are underway to protect these reptiles and their habitats.