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51-615: A few amphibians, such as some members of the frog family Brevicipitidae , undergo direct development  – i.e., they do not undergo a free-living larval stage as tadpoles – instead emerging from eggs as fully formed "froglet" miniatures of the adult morphology . Some other species hatch into tadpoles underneath the skin of the female adult or are kept in a pouch until after metamorphosis. Having no hard skeletons, it might be expected that tadpole fossils would not exist. However, traces of biofilms have been preserved and fossil tadpoles have been found dating back to

102-469: A few feed on plant matter. Frog skin has a rich microbiome which is important to their health. Frogs are extremely efficient at converting what they eat into body mass. They are an important food source for predators and part of the food web dynamics of many of the world's ecosystems . The skin is semi-permeable , making them susceptible to dehydration, so they either live in moist places or have special adaptations to deal with dry habitats. Frogs produce

153-615: A lake in the Wa country known as Nawng Hkaeo . In the Ancient Egyptian numerals , a hieroglyphic representing a tadpole was used to denote the value of 100,000. Frog See text A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (coming from the Ancient Greek ἀνούρα , literally 'without tail'). The oldest fossil "proto-frog" Triadobatrachus

204-699: A point of common ancestry. It is based on Frost et al. (2006), Heinicke et al. (2009) and Pyron and Wiens (2011). Leiopelmatidae Ascaphidae Bombinatoridae Alytidae Discoglossidae Pipidae Rhinophrynidae Scaphiopodidae Pelodytidae Pelobatidae Megophryidae Heleophrynidae Sooglossidae Nasikabatrachidae Calyptocephalellidae Myobatrachidae Limnodynastidae Ceuthomantidae Brachycephalidae Eleutherodactylidae Craugastoridae Hemiphractidae Hylidae Bufonidae Aromobatidae Dendrobatidae Leptodactylidae Allophrynidae Megophryidae Too Many Requests If you report this error to

255-457: A pouch. Male African bullfrogs ( Pyxicephalus adspersus ) will keep watch over their tadpoles, attacking anything that might be a potential threat, even though he may eat some of the tadpoles himself. Males of the Emei mustache toads ( Leptobrachium boringii ) will construct nests along riverbanks where they breed with females and keep watch over the eggs, losing as much as 7.3% of their body mass in

306-469: A prefrontal bone, presence of a hyoid plate , a lower jaw without teeth (with the exception of Gastrotheca guentheri ) consisting of three pairs of bones (angulosplenial, dentary, and mentomeckelian, with the last pair being absent in Pipoidea ), an unsupported tongue, lymph spaces underneath the skin, and a muscle, the protractor lentis, attached to the lens of the eye . The anuran larva or tadpole has

357-466: A single central respiratory spiracle and mouthparts consisting of keratinous beaks and denticles . Frogs and toads are broadly classified into three suborders: Archaeobatrachia , which includes four families of primitive frogs; Mesobatrachia , which includes five families of more evolutionary intermediate frogs; and Neobatrachia , by far the largest group, which contains the remaining families of modern frogs, including most common species throughout

408-469: A slightly warty skin and prefers a watery habitat whereas the Panamanian golden frog ( Atelopus zeteki ) is in the toad family Bufonidae and has a smooth skin. The origin of the order name Anura —and its original spelling Anoures —is the Ancient Greek alpha privative prefix ἀν- ( an- from ἀ- before a vowel) 'without', and οὐρά ( ourá ) 'animal tail'. meaning "tailless". It refers to

459-620: A variety of cuisines. Tadpoles of the megophryid frog Oreolalax rhodostigmatus are particularly large, more than 10 cm (3.9 in) in length, and are collected for human consumption in China. In Peru Telmatobius mayoloi tadpoles are collected for both food and medicine. According to Sir George Scott , in the origin myths of the Wa people in China and Myanmar , the first Wa originated from two female ancestors Ya Htawm and Ya Htai , who spent their early phase as tadpoles (" rairoh ") in

510-502: A wide range of vocalisations , particularly in their breeding season , and exhibit many different kinds of complex behaviors to attract mates, to fend off predators and to generally survive. Frogs are valued as food by humans and also have many cultural roles in literature, symbolism and religion. They are also seen as environmental bellwethers , with declines in frog populations often viewed as early warning signs of environmental damage. Frog populations have declined significantly since

561-576: Is known from the Early Triassic of Madagascar (250   million years ago ), but molecular clock dating suggests their split from other amphibians may extend further back to the Permian , 265   million years ago. Frogs are widely distributed, ranging from the tropics to subarctic regions, but the greatest concentration of species diversity is in tropical rainforest . Frogs account for around 88% of extant amphibian species. They are also one of

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612-443: Is long and spiral-shaped to efficiently digest organic matter and can be seen through the bellies of many species. Though many tadpoles will feed on dead animals if available to them, only a few species of frog have strictly carnivorous tadpoles, an example being the frogs of the family Ceratophryidae , their cannibalistic tadpoles having wide gaping mouths with which they devour other organisms, including other tadpoles. Another example

663-524: Is the name of the total group that includes modern frogs in the order Anura as well as their close fossil relatives, the "proto-frogs" or "stem-frogs". The common features possessed by these proto-frogs include 14 presacral vertebrae (modern frogs have eight or 9), a long and forward-sloping ilium in the pelvis , the presence of a frontoparietal bone , and a lower jaw without teeth. The earliest known amphibians that were more closely related to frogs than to salamanders are Triadobatrachus massinoti , from

714-511: Is the tadpoles of the New Mexico spadefoot toad ( Spea multiplicata ) which will develop a carnivorous diet along with a broader head, larger jaw muscles, and a shorter gut if food is scarce, allowing them to consume fairy shrimp and their smaller herbivorous siblings. A few genera such as Pipidae and Microhylidae have species whose tadpoles are filter feeders that swim through the water column feeding on plankton . Megophrys tadpoles feed at

765-647: Is uncertain, but agrees with arguments that it could plausibly derive from a Proto-Indo-European base along the lines of * preu , meaning 'jump'. How Old English frosc gave rise to frogga is, however, uncertain, as the development does not involve a regular sound-change . Instead, it seems that there was a trend in Old English to coin nicknames for animals ending in - g , with examples—themselves all of uncertain etymology—including dog , hog , pig, stag , and (ear)wig . Frog appears to have been adapted from frosc as part of this trend. Meanwhile,

816-530: The Antarctic Peninsula , indicating that this region was once home to frogs related to those now living in South American Nothofagus forest . A cladogram showing the relationships of the different families of frogs in the clade Anura can be seen in the table below. This diagram, in the form of a tree , shows how each frog family is related to other families, with each node representing

867-719: The Cretaceous–Paleogene extinction event associated with the Chicxulub impactor . All origins of arboreality (e.g. in Hyloidea and Natatanura) follow from that time and the resurgence of forest that occurred afterwards. Frog fossils have been found on all of the Earth's continents. In 2020, it was announced that 40 million year old helmeted frog fossils had been discovered by a team of vertebrate palaeontologists in Seymour Island on

918-457: The Middle Jurassic . Tadpoles are eaten as human food in some parts of the world and are mentioned in various folk tales from around the world. The name tadpole is from Middle English taddepol , made up of the elements tadde , ' toad ', and pol , ' head ' (modern English poll ). Similarly, pollywog / polliwog is from Middle English polwygle , made up of

969-548: The Permian , rather less than 300 million years ago, a date in better agreement with the palaeontological data. A further study in 2011 using both extinct and living taxa sampled for morphological, as well as molecular data, came to the conclusion that Lissamphibia is monophyletic and that it should be nested within Lepospondyli rather than within Temnospondyli . The study postulated that Lissamphibia originated no earlier than

1020-519: The divergence of the three groups took place in the Paleozoic or early Mesozoic before the break-up of the supercontinent Pangaea and soon after their divergence from the lobe-finned fishes . This would help account for the relative scarcity of amphibian fossils from the period before the groups split. Another molecular phylogenetic analysis conducted about the same time concluded that lissamphibians first appeared about 330 million years ago and that

1071-623: The edible frog ( Pelophylax esculentus ) is a hybrid between the pool frog ( P. lessonae ) and the marsh frog ( P. ridibundus ). The fire-bellied toads Bombina bombina and B. variegata are similar in forming hybrids. These are less fertile than their parents, giving rise to a hybrid zone where the hybrids are prevalent. The origins and evolutionary relationships between the three main groups of amphibians are hotly debated. A molecular phylogeny based on rDNA analysis dating from 2005 suggests that salamanders and caecilians are more closely related to each other than they are to frogs and

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1122-425: The middle Jurassic is slightly younger, about 155–170 million years old. The main evolutionary changes in this species involved the shortening of the body and the loss of the tail. Tadpoles of N. degiustoi constitute the oldest tadpoles found as of 2024, dating back to 168-161 million years ago. These tadpoles also showed adaptations for filter-feeding , implying residence in temporary pools by filter-feeding larvae

1173-429: The richest in species . The Anura include all modern frogs and any fossil species that fit within the anuran definition. The characteristics of anuran adults include: 9 or fewer presacral vertebrae, the presence of a urostyle formed of fused vertebrae, no tail, a long and forward-sloping ilium, shorter fore limbs than hind limbs, radius and ulna fused, tibia and fibula fused, elongated ankle bones , absence of

1224-540: The temnospondyl-origin hypothesis is more credible than other theories. The neobatrachians seemed to have originated in Africa/India, the salamanders in East Asia and the caecilians in tropical Pangaea. Other researchers, while agreeing with the main thrust of this study, questioned the choice of calibration points used to synchronise the data. They proposed that the date of lissamphibian diversification should be placed in

1275-412: The 1950s. More than one third of species are considered to be threatened with extinction and over 120 are believed to have become extinct since the 1980s. The number of malformations among frogs is on the rise and an emerging fungal disease, chytridiomycosis , has spread around the world. Conservation biologists are working to understand the causes of these problems and to resolve them. The use of

1326-496: The Indian purple frog ( Nasikabatrachus sahyadrensis ) and the tailed frogs ( Ascaphus ) of Western North America. Although there are no marine tadpoles, the tadpoles of the crab-eating frog can cope with brackish water. Some anurans will provide parental care towards their tadpoles. Frogs of the genus Afrixalus will lay their eggs on leaves above water, folding the leaves around the eggs for protection. Female Pipa frogs will embed

1377-519: The anuran lineage proper all lived in the early Jurassic period. One such early frog species, Prosalirus bitis , was discovered in 1995 in the Kayenta Formation of Arizona and dates back to the Early Jurassic epoch (199.6 to 175 million years ago), making Prosalirus somewhat more recent than Triadobatrachus . Like the latter, Prosalirus did not have greatly enlarged legs, but had

1428-540: The common names frog and toad has no taxonomic justification. From a classification perspective, all members of the order Anura are frogs, but only members of the family Bufonidae are considered "true toads". The use of the term frog in common names usually refers to species that are aquatic or semi-aquatic and have smooth, moist skins; the term toad generally refers to species that are terrestrial with dry, warty skins. There are numerous exceptions to this rule. The European fire-bellied toad ( Bombina bombina ) has

1479-422: The developing tadpoles to feed on. Despite their soft-bodied nature and lack of mineralised hard parts, fossil tadpoles (around 10 cm in length) have been recovered from Upper Miocene strata. They are preserved by virtue of biofilms , with more robust structures (the jaw and bones) preserved as a carbon film . In Miocene fossils from Libros , Spain, the brain case is preserved in calcium carbonate , and

1530-474: The early Triassic period of Madagascar (about 250 million years ago), and Czatkobatrachus polonicus , from the Early Triassic of Poland (about the same age as Triadobatrachus ). The skull of Triadobatrachus is frog-like, being broad with large eye sockets, but the fossil has features diverging from modern frogs. These include a longer body with more vertebrae . The tail has separate vertebrae unlike

1581-459: The eggs into their backs where they get covered by a thin layer of skin. The eggs will hatch underneath her skin and grow, eventually leaving as either large tadpoles (such as in Pipa parva ) or as fully formed froglets ( Pipa pipa ). Female marsupial frogs ( Hemiphractidae ) will carry eggs on her back for various amounts of time, with it going as far as letting the tadpoles develop into tiny froglets in

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1632-402: The family Ranixalidae , whose tadpoles are found in wet crevices near streams. The tadpoles of Micrixalus herrei are adapted to a fossorial lifestyle, with a muscular body and tail, eyes covered by a layer of skin, and reduced pigment. Several frogs have stream dwelling tadpoles equipped with a strong oral sucker that allows them to hold onto rocks in fast flowing water, two examples being

1683-782: The five most diverse vertebrate orders. Warty frog species tend to be called toads , but the distinction between frogs and toads is informal, not from taxonomy or evolutionary history. An adult frog has a stout body, protruding eyes , anteriorly-attached tongue , limbs folded underneath, and no tail (the tail of tailed frogs is an extension of the male cloaca). Frogs have glandular skin, with secretions ranging from distasteful to toxic. Their skin varies in colour from well- camouflaged dappled brown, grey and green to vivid patterns of bright red or yellow and black to show toxicity and ward off predators . Adult frogs live in fresh water and on dry land; some species are adapted for living underground or in trees. Frogs typically lay their eggs in

1734-518: The fused urostyle or coccyx in modern frogs. The tibia and fibula bones are also separate, making it probable that Triadobatrachus was not an efficient leaper. A 2019 study has noted the presence of Salientia from the Chinle Formation , and suggested that anurans might have first appeared during the Late Triassic . On the basis of fossil evidence, the earliest known "true frogs" that fall into

1785-463: The larval stage is confined within the egg. Tadpoles of frogs are mostly herbivorous, while tadpoles of salamanders and caecilians are carnivorous. Tadpoles of frogs and toads are usually globular, with a laterally compressed tail with which they swim by lateral undulation . When first hatched, anuran tadpoles have external gills that are eventually covered by skin, forming an opercular chamber with internal gills vented by spiracles . Depending on

1836-477: The late Carboniferous , some 290 to 305 million years ago. The split between Anura and Caudata was estimated as taking place 292 million years ago, rather later than most molecular studies suggest, with the caecilians splitting off 239 million years ago. In 2008, Gerobatrachus hottoni , a temnospondyl with many frog- and salamander-like characteristics, was discovered in Texas . It dated back 290 million years and

1887-431: The nerve cord in calcium phosphate . Other parts of the tadpoles' bodies exist as organic remains and bacterial biofilms, with sedimentary detritus present in the gut. Tadpole remains with telltale external gills are also known from several labyrinthodont groups. The oldest unambiguous fossil, a tadpole of the species Notobatrachus deguistioi from the Middle Jurassic , was published on in 2024. Tadpoles are used in

1938-478: The nineteenth century, and is paralleled widely in other Germanic languages , with examples in the modern languages including German Frosch , Norwegian frosk , Icelandic froskur , and Dutch (kik)vors . These words allow reconstruction of a Common Germanic ancestor * froskaz . The third edition of the Oxford English Dictionary finds that the etymology of * froskaz

1989-428: The paradoxical frog ( Pseudis paradoxa ) can reach up to 27 centimetres (11 in), the longest of any frog, before shrinking to a mere snout-to-vent length of 3.4–7.6 cm (1.3–3.0 in). While most anuran tadpoles inhabit wetlands , ponds , vernal pools , and other small bodies of water with slow moving water, a few species are adapted to different environments. Some frogs have terrestrial tadpoles, such as

2040-459: The same pol , 'head', and wiglen , 'to wiggle'. The life cycle of all amphibians involves a larval stage that is intermediate between embryo and adult. In most cases this larval stage is a limbless free-living organism that has a tail and is referred to as a tadpole, although in a few cases (e.g., in the Breviceps and Probreviceps genera of frogs) direct development occurs in which

2091-489: The species, there can be two spiracles on both sides of the body, a single spiracle on the underside near the vent, or a single spiracle on the left side of the body. Newly hatched tadpoles are also equipped with a cement gland which allows them to attach to objects. The tadpoles have a cartilaginous skeleton and a notochord which eventually develops into a proper spinal cord. Anuran tadpoles are usually herbivorous, feeding on soft decaying plant matter. The gut of most tadpoles

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2142-492: The tadpole's mouth changes from a small, enclosed mouth at the front of the head to a large mouth the same width as the head. The intestines shorten as they transition from a herbivorous diet to the carnivorous diet of adult frogs. Tadpoles vary greatly in size, both during their development and between species. For example, in a single family, Megophryidae , length of late-stage tadpoles varies between 3.3 centimetres (1.3 in) and 10.6 centimetres (4.2 in). The tadpoles of

2193-533: The tailless character of these amphibians. The origins of the word frog are uncertain and debated. The word is first attested in Old English as frogga , but the usual Old English word for the frog was frosc (with variants such as frox and forsc ), and it is agreed that the word frog is somehow related to this. Old English frosc remained in dialectal use in English as frosh and frosk into

2244-487: The time they spend protecting the nest. Male midwife toads ( Alytes ) will carry eggs between their legs to protect them from predators, eventually releasing them into a body of water when they are ready to hatch. Poison dart frogs ( Dendrobatidae ) will carry their tadpoles to various locations, usually phytotelma , where they remain until metamorphosis. Some female dart frogs such as the strawberry poison dart frog ( Oophaga pumilio ) will regularly lay unfertilized eggs for

2295-428: The typical three-pronged pelvic structure of modern frogs. Unlike Triadobatrachus , Prosalirus had already lost nearly all of its tail and was well adapted for jumping. Another Early Jurassic frog is Vieraella herbsti , which is known only from dorsal and ventral impressions of a single animal and was estimated to be 33 mm ( 1 + 1 ⁄ 4  in) from snout to vent. Notobatrachus degiustoi from

2346-399: The water surface using unusual funnel-shaped mouths. As a frog tadpole matures it gradually develops its limbs, with the back legs growing first and the front legs second. The tail is absorbed into the body using apoptosis . Lungs develop around the time as the legs start growing, and tadpoles at this stage will often swim to the surface and gulp air. During the final stages of metamorphosis,

2397-467: The water. The eggs hatch into aquatic larvae called tadpoles that have tails and internal gills . They have highly specialised rasping mouth parts suitable for herbivorous , omnivorous or planktivorous diets. The life cycle is completed when they metamorphose into adults. A few species deposit eggs on land or bypass the tadpole stage. Adult frogs generally have a carnivorous diet consisting of small invertebrates , but omnivorous species exist and

2448-543: The word toad , first attested as Old English tādige , is unique to English and is likewise of uncertain etymology. It is the basis for the word tadpole , first attested as Middle English taddepol , apparently meaning 'toad-head'. About 88% of amphibian species are classified in the order Anura. These include over 7,700 species in 59 families , of which the Hylidae (1062 spp.), Strabomantidae (807 spp.), Microhylidae (758 spp.), and Bufonidae (657 spp.) are

2499-438: The world. The suborder Neobatrachia is further divided into the two superfamilies Hyloidea and Ranoidea . This classification is based on such morphological features as the number of vertebrae, the structure of the pectoral girdle , and the morphology of tadpoles. While this classification is largely accepted, relationships among families of frogs are still debated. Some species of anurans hybridise readily. For instance,

2550-540: Was already commonplace. The evolution of modern Anura likely was complete by the Jurassic period. Since then, evolutionary changes in chromosome numbers have taken place about 20 times faster in mammals than in frogs, which means speciation is occurring more rapidly in mammals. According to genetic studies, the families Hyloidea , Microhylidae , and the clade Natatanura (comprising about 88% of living frogs) diversified simultaneously some 66 million years ago, soon after

2601-473: Was hailed as a missing link , a stem batrachian close to the common ancestor of frogs and salamanders, consistent with the widely accepted hypothesis that frogs and salamanders are more closely related to each other (forming a clade called Batrachia) than they are to caecilians. However, others have suggested that Gerobatrachus hottoni was only a dissorophoid temnospondyl unrelated to extant amphibians. Salientia (Latin salire ( salio ), "to jump")

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