Poikilothermy is an evolutionary adaptation of a species or (in medicine and physiology) a state of an organism in which the body temperature of a living being varies widely depending on the temperature of the external environment.
This is true of most invertebrates, as well as fish, amphibians, and reptiles. In winter, cold-blooded animals fall into a state of stupor, which is associated with a significant decrease in body temperature.
Poikilothermia in living beings
Poikilothermic organisms include all modern taxa of the organic world, except for two classes of vertebrates - birds and mammals. For a long time it was believed that all mammals are warm-blooded, but modern research has shown that the naked mole rat is the only cold-blooded representative of this class known today; it was also assumed that the extinct Balearic goat belonged to the poikilothermic mammals. The question of whether dinosaurs were cold-blooded animals is also debatable, but recently scientists are more inclined to the version of their warm-bloodedness, based on studies of oxygen isotopes, growth rates, etc. In addition, the number of finds of dinosaurs with dense feather-like covers is also constantly growing, even in those species that had nothing to do with flight. It is believed that warm-bloodedness is the basal feature of all archosaurs, and even many crocodylomorphs, including the ancestors of modern crocodiles, were warm-blooded. The often distinguished concept of inertial warm-bloodedness or gigantothermia - when the body warms up in the sun, after which, due to the large size of the body, it keeps a relatively constant temperature, like large modern crocodiles, should not be removed from the definition of poikilothermia, since the body is still unable to produce enough heat on its own.
Reptiles poikilothermic
The term cold-blooded is used as a synonym for poikilothermy. The comparison is wrong. Poikilothermic animals are not active at low temperatures, and some even die.
The latter option is relevant for the inhabitants of the tropics. Reptiles from there die at temperatures below 20-25 degrees. Reptiles are divided into 4 orders. Let's take a look at some representatives.
Galapagos elephant tortoise
Represents a detachment of turtles among reptiles. It contains about 300 species. The Galapagos is the largest of the terrestrial tortoises. In the sea, the giant is different - a leathery species. Its representatives are gaining a 900-kilogram mass. Galapagos tortoises weigh about 3 centners. The species is dying out, listed in the International Red Book.
Soft-bodied tortoise trionyx
This is a freshwater animal. Instead of horny plates, the Trionyx carapace is leathery. Differences are also paws with 5 fingers, 3 of which are clawed and connected by a membrane. Trionix weighs 3-4 kilos, and reaches a length of 30 centimeters.
All turtles are poikilothermic animals. This does not prevent their extensive classification. So, in addition to land, freshwater and marine, there are side-necked and hidden-necked species. The former hide their heads from the side of one of the forelimbs. Hidden neck turtles fold their necks into an S.
