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Many frogs have webbed feet and the degree of webbing is directly proportional to the amount of time the species spends in the water. [54] The completely aquatic African dwarf frog ( Hymenochirus sp.) has fully webbed toes, whereas those of White's tree frog ( Litoria caerulea ), an arboreal species, are only a quarter or half webbed. [ 55 ]
Adult frogs do not have tails and caecilians have only very short ones. [69] Didactic model of an amphibian heart. Salamanders use their tails in defence and some are prepared to jettison them to save their lives in a process known as autotomy. Certain species in the Plethodontidae have a weak zone at the base of the tail and use this strategy ...
The unipapillary kidney with a single renal pyramid is the simplest type of kidney in mammals, from which the more structurally complex kidneys are believed to have evolved. [ 17 ] [ 6 ] [ 18 ] Differences in kidney structure are the result of adaptations during evolution to variations in body mass and habitats (in particular, aridity ) between ...
Unlike mammals, the kidneys of reptiles do not have a clear distinction between cortex and medulla. [43] The kidneys lack the loop of Henle, have fewer nephrons (from about 3,000 to 30,000), and cannot produce hypertonic urine. [3] [21] Nitrogenous waste products excreted by the kidneys may include uric acid, urea and ammonia. [55]
Their kidneys (metanephros) and large intestines are also well-suited to water retention. Most mammals do not lay eggs, but corresponding structures develop inside the placenta. The ancestors of true amniotes, such as Casineria kiddi, which lived about 340 million years ago, evolved from amphibian reptiliomorphs and resembled small lizards.
True frogs is the common name for the frog family Ranidae. They have the widest distribution of any frog family. They are abundant throughout most of the world, occurring on all continents except Antarctica. The true frogs are present in North America, northern South America, Europe, Africa (including Madagascar), and Asia.
The development of the kidney proceeds through a series of successive phases, each marked by the development of a more advanced kidney: the archinephros, pronephros, mesonephros, and metanephros. [1] The pronephros is the most immature form of kidney, while the metanephros is most developed. The metanephros persists as the definitive adult kidney.
The diet of water-holding frogs is broad and ranges from worms and insects to tadpoles and other small frogs. [3] [12] Frogs may eat their own tadpoles but only when food availability is scarce. [15] On dry land they will also feed on ants and termites. [12]