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An ectotherm (from the Greek ἐκτός (ektós) "outside" and θερμός (thermós) "heat"), more commonly referred to as a "cold-blooded animal", [1] is an animal in which internal physiological sources of heat, such as blood, are of relatively small or of quite negligible importance in controlling body temperature. [2]
Ribs are generally absent, so the lungs are filled by buccal pumping and a frog deprived of its lungs can maintain its body functions without them. [69] The fully aquatic Bornean flat-headed frog (Barbourula kalimantanensis) is the first frog known to lack lungs entirely. [72] Frogs have three-chambered hearts, a feature they share with lizards.
[100] [101] Lungs and swim bladders are homologous (descended from a common ancestral form) as is the case for the pulmonary artery (which delivers de-oxygenated blood from the heart to the lungs) and the arteries that supply swim bladders. [102] Air was introduced into the lungs by a process known as buccal pumping. [103] [104]
The Bornean flat-headed frog (Barbourula kalimantanensis) is a species of frog in the family Bombinatoridae. [2] For many years, it was thought to be the only frog with no lungs . [ 3 ] However, micro CT scanning revealed that, like all other known frog species, the Bornean flat-headed frog has lungs, though they are tiny.
The marsh frog (Pelophylax ridibundus) is a species of true frog and the largest frog native to Europe; females of this sexually dimorphic species may be up to 17 centimetres (6.7 in) long. The marsh frog feeds mainly on insects, but it also eats smaller amphibians, fish, and rodents.
All extant (living) amphibians belong to the monophyletic subclass Lissamphibia, with three living orders: Anura (frogs and toads), Urodela (salamanders), and Gymnophiona . Evolved to be mostly semiaquatic , amphibians have adapted to inhabit a wide variety of habitats , with most species living in freshwater , wetland or terrestrial ecosystems ...
In fish a countercurrent flow (lower diagram) of blood and water in the gills is used to extract oxygen from the environment. [56] [57] [58] Fig. 23 The respiratory mechanism in bony fish. The inhalatory process is on the left, the exhalatory process on the right. The movement of water is indicated by the blue arrows. Oxygen is poorly soluble ...
Sea slugs respire through a gill (or ctenidium). Aquatic respiration is the process whereby an aquatic organism exchanges respiratory gases with water, obtaining oxygen from oxygen dissolved in water and excreting carbon dioxide and some other metabolic waste products into the water.