Frogs and Toads of the United States
There are 14 families of frogs and toads found in the United States represented by 120 species in 25 Genus.
Adult frogs and toads lack tails. They have well developed forelimbs and even larger hind legs. They lack a clear neck, with the head seeming to be attached directly to the body. Most have a well developed ear, as evidence externally by a conspicuous tympanum, and a voice used to attract mates, drive off intruders, and to signal distress and presence. All are cornivorous as adults. With their moist skin, most frogs and toads are prone to dessication, and therefore are confined to wet or moist habitats. However, some species have adapted to more arid habitats by burrowing into the soil of hiding beneath rocks or logs to avoid the heat of the day
Most species return to the water to breed. Eggs are laid in the water and are fertilized by the male while clasping the female. The eggs hatch into tadpoles which later transform into young frogs and toads. A number of frogs and toads lay their eggs in shaded moist sites on land, or in nests constructed over water. The eggs may hatch into tadpoles that either drop into the water, are swept into the water by rains, or are carried to the water by a parent. Other species bypass the tadpole stage, their eggs hatching directly into miniature frogs. Finally, the African live bearing toad, Nectopgrynoides, and the North American Tailed Frog, Ascaphus, are unique among frogs and toads in the they fertilize the eggs within the cloaca of the female.
One species on the Northwestern United States and southwestern Canada. These are primative frogs with 2 pairs of unattached ribs and 9 presacral vertebrae. The pupil is vertical. None of the species has a true tail, but all possess tail wagging muscles. Male Ascaphus have a unique tail like extension of the vent that servers as a copulatory organ for passing sperm directly into the body of the female, while clasping her around the waist.
All tailed frogs live in cool mountain habitats, but reproduction varies. Leiopelma lays its eggs on damp earth where they hatch 6 weeks later as miniature frogs. Ascaphus lays its eggs in cold mountain streams where they hatch into tadpoles, transforming into frogs more than 6 months later.
Bombinoatoridae is a family of toad found in Eurasia. Species of the family have flattened bodies and some are highly toxic.
There is 1 species found in the United States which is an Introduced Species.
Bufonidae, or more commonly called toads, are squat and plump with rough warty skin. They have horizontal pupils, no teeth on the upper jaw, and lack the anterior breastbone. Enlarged parotoid glands are located on each side of the neck over or behind the tympanum. These glands secrete a viscous white poison, which gets smeared in the mouth of any would be predator. The poison inflames the mouth and throat, causing nausea, irregular heartbeat, and, in extreme cases, death. Survivors of such a poisoning seldom ever again attack toads.
Toads in our range breed in spring and summer. Males congregate at the breeding ponds and sing in order to attract females. Males clasp the willing females around the body behind the forelimbs. Males also have rudimentary ovary, which can become functional if the testes are damaged of removed. Eggs are usually laid in strings attached to vegetation. They hatch into tiny black tadpoles which weeks later metomorphose into little toads.
There are 26 species representing 3 genus found in the United States, 2 of which are Introduced.
Craugastoridae, commonly known as fleshbelly frogs, is a family of New World direct-developing frogs. They are found from the southern United States southwards to Central and South America.
There is 1 native species found in the United States.
Dendrobatidae, or the Poison Dart From (also known as dart-poison fron, poison frog, or formerly as poison arrow frog) are native to tropical Central and South America. These species are diurnal and often have brightly colored bodies. This bright coloration correlated with the toxicity of the species, making them aposemoatic. Some species of the family exhibit extremely bright coloration along with high toxicity, while others have cryptic coloration with minimal to no amount of observed toxicity.
There is 1 species found in the United States which is an Introduced Species.
The Eleutherodactylidae are a family of direct-developing frogs native to northern South America, the Carribean, and southernmost North America. They are sometimes known under the common name Rain frogs. Formerly the subfamily Eleuthrodactylinae of the family Leptodactylidae, it was raised to be the family status following a major revision of New World direct-developing frogs in 2008. As currently defined, the family has more than 200 species.
There is 7 species representing 1 genus found in the United States all of which are native to the U.S.
There are 5 genera with 35 species found in the United States. Treefrogs are small and have slender legs and their pupils are horizontal. Arboreal treefrogs are typically walkers and climbers, and are reluctant jumpers. Their toe tips are expanded into sticky adhesive pads used in climbing. Climbing is further aided by the presence of cartilage between the last two bones of each toe. The cartilage allows the tips of the toe to swivel backward and sideways while keeping the sticky toe pad flat against the climbing surface. A few treefrogs, such as the North American Acris, have returned to a terrestrial existence, lack the large toe pads, and are active leapers.
Male treefrogs in our range typically call while perched on vegetation in, over or near water. Males clasp females just behind the forelimbs. Masses of eggs are laid in the water.
The single species that occurs in the United States have horizintal pupils, and a T-shaped bone in the tip of each toe. Males of some species congregate together to call in load choruses to attract females to the breeding ponds, but males of most species call singly, often while hidden in vegetation or burrows. Breeding males clasp the females behind the forelimbs. Some species, like Leptodactylus, lay numerous eggs in foam nests in the water. On hatching, the tadpoles escape into the water where they live until metamorphosing into frogs.
Only 2 genra with 4 species total are found in the United States, there are Gastrophryne and Hypopachus. Narrow-mouhted frogs have a reduced shoulder girdle. The North American species lack teeth, and have a fold of skin across the back of the narrow, pointed head. They body is plump and the skin smooth and moist. The legs are short and the hind feet have enlarged tubercles used in digging. They are scretive creatures active only at night and feed almost excusively on ants.
Males give a bleating call to attract feamles to the breeding ponds. In addition to being clasped firmly behind the forelimbs by the male, the female narrow-mouthed frogs sticky skin scretion also holds the breeding pair together. The eggs are laid in a thin, floating film and hatch a few days later. Tadpoles metamorphose in about 30 days.
Pelodryadidae, also known as Australian Treefrogs (although not all members are arboreal) are a family of frogs found in the region of Australia and New Guinea. Some authorities group then within the Hylidae as family Pelodryadinae.
There is 1 species found in the United States that is an Introduced species.
One species, Xenopus laevis, has been introducted to the United States.
Tongueless frogs have attached ribs and eight presacral vertebrae. Their pupils are round. The South American species have starlike projections on the tips of the toes of the front feet while the African species have simple pointed toes on the front feet. The latter attach their eggs singly to submerged vegetation, logs, or stones. Thousands of eggs are laid at a time. During breeding, the male clasps the female around the waist.
True frogs have a bony breastbone and horizontal pupils. North American species have large frogs with slim waists, long legs, pointed toes, and extensive webbing on the hind feet. They are excellent jumpers. The adults are truly amphibious, typically living along the edge of water and entering it daily to catch prey, flee danger, or to mate. They are all voracious cornivores, feeding primarily on insects, spiders, and crustaceans, but readily accepting anything else that can be caught and swallowed.
Mating usually is initiated in the springs with aggregations of males calling in chorus to attract females to the breeding site. The breeding male has swollen forearms and thumbs for clasping the female behind her forelegs. In the water, female Rana may lay strings or rafts containing up to 20,000 eggs. Eggs hatch within a month, with tadpoles metamorphosing into frogs 6 to 24 months later.
Only 1 species, Rhinophrynus dorsalis, found from Coast Rica to Texas. This frog lacks a breastbone. The pupil is vertical. In addition, its tongue is attached in the back of the mouth and free in the front, unlike the typical toad or frog, so that it protrudes like the tongue of most vertebrates. Rhinophrynus is adept at burrowing, making use of the spade on each hind foot to shuffle backward into the soil. Breeding males clasp the females around the waist. Eggs are laid in the water.
The Scaphiopodidae are a family of American Spadefoot toads, which are native to North America. The family is small, comprising only 7 different species. The American Spadefoot toads are of typical shape to most fossorial (or burrowing) frogs. They are round with short legs and protruding eyes. As suggested by their name, these frogs have hard, keratinous protrusions present on their feet, which help them to dig. Like most fossorial frogs, they dig backwards into the ground. They differ from true toads because they have vertical pupils and no paratoid gland.
There is 7 species, representing 2 genus, found in the United States all of which are native to the U.S.
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