1.There are 5,250 species of frogs and toads. The name "frogs" and "toads" has no scientific basis. Usually, species with longer hind limbs, smooth and wetter skin and well developed foot webs for swimming are named frogs.
"Toads" have bulkier bodies, often with warts, and shorter hind legs for crawling and hopping. The feet webs are less developed, as they pass less time in the water.
No, toads do not cause warts (they are produced by viruses). In some countries, there is the believe toads transmit scabies (this disease is caused by a mite).
This is misleading, as tree frogs, poison dart frogs or harlequin frogs are closely related to common toads (Bufo), while many species related to common frogs (Rana) may be called toads.
2.World's largest frog is the African Goliath frog (Conraua goliath) from central Africa: 13 inches (33 cm) in body length (legs excluded), and weighs up to 7 lb (3 kg). World's largest toad is the cane toad (Bufo marinus): the largest individual weighed 2.65 kg (5.8 lb) with a body length of 38 cm (15 in). World's largest frogs ever was Belzebufo, which lived 70-65 MA ago in Madagascar: 40 cm (1.3 ft) in body length. This giant was closely related to the South American horned frogs (Ceratophrys).
3.The first anurans (frogs and toads) appeared 150 million years ago.
4.Because they are cold blooded animals, anurans have a cold touch, and also sticky because of the moisturizing mucus. Most are nocturnal and all have four fingers at each fore limb and five toes at each rear limb.
5.Frogs can jump 9 times their body length, due to the powerful rear limbs. Species that are arboreal have digits ending in cups.
6.Most anurans lay eggs in the water, in piles that containing several thousands. The eggs have a few millimeters in diameter and are wrapped in a protective gelatin. The smith frog builds a small secluded pool in which lays just a few eggs. When rains come, the pool gets connected to the river, releasing the tadpoles (larvae) there. The tadpole looks like a fish, have gills and mouth caps but, in time, it grows limbs and reabsorbs the tail, turning into a froglet. Unlike adults, tadpoles are usually vegetarian.
Some tropical frogs lay their eggs on the ground, in moist places beneath the leaves and stones. In this case, the tadpole stage is skipped, and from the egg goes out a froglet.
The males of the midwife toads from Europe carry the eggs on the back, till the hatching of the tadpoles. Helmeted frogs and related species from tropical America carry their eggs on the back, and from them hatch directly froglets. Poison dart frogs lay eggs on leaves, but the male will transport the hatched tadpoles to a lake or stream.
The female of the marsupial frog has a large pouch on the back which she uses for carrying the eggs. Tadpoles develop inside the pouch living from the yolk deposited in their stomach. A few weeks later, froglets emerge from the pouch.
The gastric brooding frogs of Australia, now extinct, used to swallow the eggs and keep them in their stomach. Later, the female spitted out froglets.
In Darwin's frogs (Rhinoderma), two species from Chile, the female lay eggs on the ground and the male will engulf them and the tadpoles into its enlarged vocal sac. In one Darwin's Frog, the tadpoles are released into water to complete their development, while in the other completely formed froglets get out of the male's mouth. A male can carry 5 to 15 offspring.
In western Africa there are even toads with internal fecundation, an unique case amongst amphibians.
7.Anurans live on living moving prey (their eyesight cannot detect still prey). Their appetite is amazing: the African bull frog (Pyxicephalus) can swallow anything of its size, including venomous snakes, giant millipedes, scorpions, finches and even other bull frogs. So does the South American bull frog (Leptodactylus pentadactylus).
After locating a prey, a frog/toad approaches it, dashes on it and catches it with the sticky tip of the tongue. Prey is not bitten or chewed, but swallowed alive. When swallowing, frogs use to blink: their big eyes help pushing down to the neck its prey.
8.Some frogs are aggressive, dashing towards the attacker to bite, even if they do not have real teeth. Because of their big mouths, some predators can be impressed by this behavior.
Many species have a camouflage brown or green coloration, but some frogs are vividly colored in various patterns warning about their potent venom. The venom from the skin of poison dart frogs can kill a human in an amount of just 0.00001 g if it enters the blood flow. From this venom is made the famous curara poison for arrows (hence the name of the animals). This venom comes from the ants and mites consumed by these frogs.
Common toads from the genus Bufo produce hallucinogens called bufotoxins. If you ever looked at a toad, you probably saw two conspicuous bumps located close to their ears. These are the parotoid glands, producing the bufotoxins. If you push them, a foamy whitish stuff will be secreted: it's the toad's venom.
Of course, the bufotoxins are toxic (as their name suggests) and a dog swallowing a toad can be killed by these chemicals. The bufotoxins explain the ecological disaster produced by the cane toad (Bufo marinus) in Australia. Most local predators are killed by this deadly cocktail; one exception is a non-venomous snake.
Chinese traditional medicine uses the bufotoxin extract from the skin of some Asian toads as a variant of the common toad (Bufo bufo gargarizans). In fact, bufotoxins are also employed in homeopathy.
Bufotoxins are "smoked" as drugs by knowers, like hashish or marijuana.
An "eye" defense mechanism is found in the four-eyed or false-eyed frogs (Physalaemus) from tropical America. The frogs have on their rear part a pair of big black "eyes", but they normally look uniformly brown. When threatened, one of these frogs turns around towards their enemy, rear first, and inflates itself. Most predators are scared by the sudden change and think that they're facing the head of a bigger animal.
9.Frog legs are an appreciated dish in Europe and North America. They are captured during the night, using lanterns that blind them. The American bull frog is extremely appreciated due to its size. Now, the European demand is satisfied mainly from Asia.
In fact, the Goliath frog is so appreciated by locals that poaching led it on the brink of extinction.
10.A croak is produced by frogs by pushing air through the larynx in the throat. Most frogs have vocal sacs that amplify the sound. These are elastic skin membranes that work by distention.
Some frogs can be heard from miles away. That's why there are South American bullfrogs, North American bullfrogs, Asian bullfrogs and African bullfrogs.
Croaks can be simpler, isolated sounds, or complex and long, sometimes forming "laughs". They can sounds like bells, cackles, trills, cuckoo calls, barks, whistles, flute, meows, grunts, buzzings, zooms, hums, started engine, hammer hitting an anvil, rowing, drum beats, metallic, and others.
Croaks are basically love serenades, meant to attract a mate. Males can sing individually or gather in groups named choruses. Sometimes, females too can croak, like in Polypedates (Asian frogs), emitting similar croaks to the males, and which act like catalysts for boosting breeding activity in the group.
Some species have a rain croak, as they perceive air humidity before a rainfall. Croaks can also be for territory defense, when a male chases away others. Some frog species emit a distress high pitched croak when captured by a predator (like in Leptodactylus from tropical America).
Croak is unique to species and in many cases used for establishing the difference between species that are physically indistinguishable. Moreover, distinct populations of the same species can have different "dialects" and "accents".
The clawed frogs (Africa) and star fingered frogs (South America), (Pipidae family) are perfectly adapted to water, that's why they croak underwater and have ears that perceive the underwater croaks!
The concave-eared torrent frog (Amolops tormotus) from eastern China overcomes the noise of the waterfalls it lives in by emitting ultrasound calls!
The only other vertebrates known to use ultrasounds are all mammals: bats, dolphins, whales and a few rodents. Ultrasounds have frequencies over 20 kHz and cannot be heard by the human ear. These frogs emit ultrasounds of over 128 kHz!
Some frogs from tropical America can detect ultrasounds emitted by bats and shut up when perceiving them (they are preyed on by bats), but it has not been proven yet if they also emit ultrasounds.
There are frogs that do not croak at all. The tailed frogs (Ascaphus) from Northeastern US and those from New Zealand (Leiopelma) are the most primitive living frog species and do not have any apparatus for emitting sounds.
11.Some frogs, like wood frog (Rana sylvatica), can spend the winter frozen in the ice and revive in the spring, at the melting of the ice, due to the production of an antifreeze protein.
12.Fish and frogs are insensitive to caresses, while the heart rhythm of lizards and mice increases when caressed.
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