In November, 1970, NASA sent two bullfrogs into space for six days during the Orbiting Frog Otolith mission to test weightlessness. a b Kuzmin, Sergius L. (1999-09-29). " Bombina bombina". AmphibiaWeb. University of California, Berkeley . Retrieved 2012-06-15.

In many arboreal frogs, a small "intercalary structure" on each toe increases the surface area touching the substrate. Furthermore, many arboreal frogs have hip joints that allow both hopping and walking. Some frogs that live high in trees even possess an elaborate degree of webbing between their toes. This allows the frogs to "parachute" or make a controlled glide from one position in the canopy to another. [54]

Casselman, Anne (2008-05-21). " "Frog-amander" fossil may be amphibian missing link". National Geographic News. Archived from the original on May 25, 2008 . Retrieved 2012-07-05.

Bullfrog". Ohio Department of Natural Resources. Archived from the original on 2012-08-18 . Retrieved 2012-06-19. Harvey, M. B.; Pemberton, A. J.; Smith, E. N. (2002). "New and poorly known parachuting frogs (Rhacophoridae: Rhacophorus) from Sumatra and Java". Herpetological Monographs. 16: 46–92. doi: 10.1655/0733-1347(2002)016[0046:NAPKPF]2.0.CO;2. S2CID 86616385. Sabater-Pi, J. (1985). "Contribution to the biology of the Giant Frog ( Conraua goliath, Boulenger)". Amphibia-Reptilia. 6 (1): 143–153. doi: 10.1163/156853885x00047. Suthers, R.A.; Narins, P.M.; Lin, W; Schnitzler, H; Denzinger, A; Xu, C; Feng, A.S. (2006). "Voices of the dead: complex nonlinear vocal signals from the larynx of an ultrasonic frog". Journal of Experimental Biology. 209 (24): 4984–4993. doi: 10.1242/jeb.02594. PMID 17142687. Some frogs, such as the poison dart frogs, are especially toxic. The native peoples of South America extract poison from these frogs to apply to their weapons for hunting, [185] although few species are toxic enough to be used for this purpose. At least two non-poisonous frog species in tropical America ( Eleutherodactylus gaigei and Lithodytes lineatus) mimic the colouration of dart poison frogs for self-protection. [186] [187] Some frogs obtain poisons from the ants and other arthropods they eat. [188] Others, such as the Australian corroboree frogs ( Pseudophryne corroboree and Pseudophryne pengilleyi), can synthesize the alkaloids themselves. [189] The chemicals involved may be irritants, hallucinogens, convulsants, nerve poisons or vasoconstrictors. Many predators of frogs have become adapted to tolerate high levels of these poisons, but other creatures, including humans who handle the frogs, may be severely affected. [190]

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The food then moves through the oesophagus into the stomach where digestive enzymes are added and it is churned up. It then proceeds to the small intestine (duodenum and ileum) where most digestion occurs. Pancreatic juice from the pancreas, and bile, produced by the liver and stored in the gallbladder, are secreted into the small intestine, where the fluids digest the food and the nutrients are absorbed. The food residue passes into the large intestine where excess water is removed and the wastes are passed out through the cloaca. [74]

Although care of offspring is poorly understood in frogs, up to an estimated 20% of amphibian species may care for their young in some way. [170] The evolution of parental care in frogs is driven primarily by the size of the water body in which they breed. Those that breed in smaller water bodies tend to have greater and more complex parental care behaviour. [171] Because predation of eggs and larvae is high in large water bodies, some frog species started to lay their eggs on land. Once this happened, the desiccating terrestrial environment demands that one or both parents keep them moist to ensure their survival. [172] The subsequent need to transport hatched tadpoles to a water body required an even more intense form of parental care. [171]San Mauro, Diego; Vences, Miguel; Alcobendas, Marina; Zardoya, Rafael; Meyer, Axel (2005). "Initial Diversification of living amphibians predated the breakup of Pangaea". The American Naturalist. 165 (5): 590–599. doi: 10.1086/429523. JSTOR 429523. PMID 15795855. S2CID 17021360. (subscription required) At the other extreme, the striped burrowing frog ( Cyclorana alboguttata) regularly aestivates during the hot, dry season in Australia, surviving in a dormant state without access to food and water for nine or ten months of the year. It burrows underground and curls up inside a protective cocoon formed by its shed skin. Researchers at the University of Queensland have found that during aestivation, the metabolism of the frog is altered and the operational efficiency of the mitochondria is increased. This means that the limited amount of energy available to the comatose frog is used in a more efficient manner. This survival mechanism is only useful to animals that remain completely unconscious for an extended period of time and whose energy requirements are low because they are cold-blooded and have no need to generate heat. [98] Other research showed that, to provide these energy requirements, muscles atrophy, but hind limb muscles are preferentially unaffected. [99] Frogs have been found to have upper critical temperatures of around 41 degrees Celsius. [100] Locomotion a b Flam, F. (1995). "Finding earliest true frog will help paleontologists understand how frog evolved its jumping ability". Knight Ridder/Tribune News Service. Archived from the original on 2013-05-13 . Retrieved 2012-06-10. Because frog toxins are extraordinarily diverse, they have raised the interest of biochemists as a "natural pharmacy". The alkaloid epibatidine, a painkiller 200 times more potent than morphine, is made by some species of poison dart frogs. Other chemicals isolated from the skins of frogs may offer resistance to HIV infection. [227] Dart poisons are under active investigation for their potential as therapeutic drugs. [228] Frogs may lay their in eggs as clumps, surface films, strings, or individually. Around half of species deposit eggs in water, others lay eggs in vegetation, on the ground or in excavations. [133] [134] [135] The tiny yellow-striped pygmy eleuth ( Eleutherodactylus limbatus) lays eggs singly, burying them in moist soil. [136] The smoky jungle frog ( Leptodactylus pentadactylus) makes a nest of foam in a hollow. The eggs hatch when the nest is flooded, or the tadpoles may complete their development in the foam if flooding does not occur. [137] The red-eyed treefrog ( Agalychnis callidryas) deposits its eggs on a leaf above a pool and when they hatch, the larvae fall into the water below. [138]

Hopkins, G.R. & Brodie Jr, E.D. (2015) Occurrence of amphibians in saline habitats: a review and evolutionary perspective. Herpetological Monographs, 29: 1-27. tadpole, n.1.". Oxford English Dictionary (Onlineed.). Oxford University Press. (Subscription or participating institution membership required.) Mörs, Thomas; Reguero, Marcelo; Vasilyan, Davit (2020). "First fossil frog from Antarctica: implications for Eocene high latitude climate conditions and Gondwanan cosmopolitanism of Australobatrachia". Scientific Reports. 10 (1): 5051. Bibcode: 2020NatSR..10.5051M. doi: 10.1038/s41598-020-61973-5. PMC 7181706. PMID 32327670. Wostl, Elijah, Eric N. Smith, and Robert N. Reed. 2016. Origin and Identity of Fejervarya (Anura: Dicroglossidae) on Guam. Pacific Science 70(2):233-241. https://doi.org/10.2984/70.2.9Muntz, W. R. A.; Scientific American Offprints (1964). "Vision in frogs". Scientific American. W. H. Freeman. 210 (3): 110–9. ASIN B0006RENBO. Bibcode: 1964SciAm.210c.110M. doi: 10.1038/scientificamerican0364-110. OCLC 15304238. PMID 14133069.