Most frogs are characterized by a short body, webbed digits, protruding eyes, bifid tongue and the absence of a tail. Frogs are widely known as exceptional jumpers, and many of the anatomical characteristics of frogs, particularly their long, powerful legs, are adaptations to improve jumping performance. Due to their permeable skin, frogs are often semi-aquatic or inhabit humid areas, but move easily on land.
They typically lay their eggs in puddles, ponds or lakes, and their larvae, called tadpoles, have gills and tails to develop in water. Adult frogs follow a carnivorous diet, mostly of arthropods, annelids and gastropods. Frogs are most noticeable by their call, which can be widely heard during the night or day, mainly in their mating season.
The distribution of frog’s ranges from tropic to subarctic regions, but most species are found in tropical rainforests. Consisting of more than 5,000 species described, they are among the most diverse groups of vertebrates. However, populations of certain frog species are declining significantly.
A popular distinction is often made between frogs and toads on the basis of their appearance, but this has no taxonomic basis. In addition to their ecological importance, frogs have many cultural roles, such as in literature, symbolism and religion, and they are also valued as food and as pets.
Many frogs contain mild toxins that make them unpalatable to potential predators. For example, all toads have large poison glands—the parotoid glands—located behind the eyes, on the top of the head. Some frogs, such as some poison dart frogs, are especially toxic. The chemical makeup of toxins in frogs varies from irritants to hallucinogens, convulsants, nerve poisons, and vasoconstrictors. Many predators of frogs have adapted to tolerate high levels of these poisons. Others, including humans, may be severely affected.
Some frogs obtain poisons from the ants and other arthropods they eat; others, such as the Australian Corroboree Frogs can manufacture an alkaloid not derived from their diet. Some native people of South America extract poison from the poison dart frogs and apply it to their darts for hunting, although few species are toxic enough to be used for this purpose.
It was previously a misconception the poison was placed on arrows rather than darts. The common name of these frogs was thus changed from “poison arrow frog” to “poison dart frog” in the early 1980s. Poisonous frogs tend to advertise their toxicity with bright colors, an adaptive strategy known as aposematism. There are at least two non-poisonous species of frogs in tropical America that mimic the coloration of dart poison frogs’ coloration for self-protection.
Here is the list of deadly poisonous frog around the earth.
Golden Poison Frog:
Phyllobates terribilis, the golden poison frog or the golden dart frog, is a poison dart frog endemic to the Pacific coast of Colombia. The optimal habitat of P. terribilis is the rainforest with high rain rates (5 m or more), altitude between 100–200 m, temperature of at least 26 °C, and relative humidity of 80–90%.
In the wild, P. terribilis is a social animal, living in groups of up to six individuals; however, captive P. terribilis can live in much larger groups. Terribilis frogs are often considered innocuous due to their small size and bright colours; however, wild specimens are lethally toxic. This poison dart frog is confirmed to have killed humans who touched the wild frog directly.
he golden poison frog’s skin is densely coated in alkaloid poison, one of a number of poisons common to dart frogs , which prevents nerves from transmitting impulses, leaving the muscles in an inactive state of contraction. This can lead to heart failure or fibrillation. Alkaloid batrachotoxins can be stored by frogs for years after the frog is deprived of a food-based source, and such toxins do not readily deteriorate, even when transferred to another surface. Chickens and dogs have died from contact with a paper towel on which a frog had walked.
The golden poison frog is not venomous, but poisonous; venomous animals use their toxins to kill their prey. Like most poison dart frogs, P. terribilis uses poison only as a self-defense mechanism and not for killing prey. The most venomous animal is the box jellyfish, which is only slightly less toxic than P. terribilis.
The average dose carried will vary between locations, and consequent local diet, but the average wild P. terribilis is generally estimated to contain about one milligram of poison, enough to kill about 10,000 mice. This estimate will vary in turn, but most agree this dose is enough to kill between 10 and 20 humans, which correlate to up to two African bull elephants. This is roughly 15,000 humans per gram.
This extraordinarily lethal poison is very rare. Batrachotoxin is only found in three poisonous frogs from Colombia and three poisonous birds from Papua New Guinea: Pitohui dichrous, Pitohui kirhocephalus and Ifrita kowaldi. Other related toxins are histrionicotoxin and pumiliotoxin, which are found in frog species from the genus Dendrobates.
The golden poison frog, like most other poisonous frogs, stores its poison in skin glands. Due to their poison, the frogs taste vile to predators; P. terribilis poison kills whatever eats it, except for a snake, Liophis epinephelus. This snake is resistant to the frog’s poison, but is not completely immune.
The poisonous frogs are perhaps the only creatures to be immune to this poison. Batrachotoxin attacks the sodium channels of the cells, but the frog has special sodium channels the poison cannot harm.
Since easily purchased foods such as fruit flies and extra-small crickets are not rich in the alkaloids required to produce batrachotoxins, captive frogs do not produce toxins and they eventually lose their toxicity in captivity. In fact, many hobbyists and herpetologists have reported that most dart frogs will not consume ants at all in captivity, though ants constitute the larger portion of their diet in the wild.
This is likely due to the unavailability of the natural prey species of ants to captive frog keepers. Though all poison frogs lose their toxicity when deprived of certain foods, and captive-bred golden poison frogs are born harmless, a wild-caught poison frog can retain alkaloids for years. It is not clear which prey species supplies the potent alkaloid that gives golden poison frogs their exceptionally high levels of toxicity, or whether the frogs modify another available toxin to produce a more efficient variant, as do some of the frog’s cousins from the genus Dendrobates.
Thus, the high toxicity of P. terribilis appears to be due to the consumption of small insects or other arthropods, and one of these may truly be the most poisonous creature on Earth. Scientists have suggested the crucial insect may be a small beetle from the family Melyridae. At least one species of these beetles produces the same toxin found in P. terribilis. The beetle family Melyridae is cosmopolitan. Its relatives in Colombian rainforests could be the source of the batrachotoxins found in the highly toxic Phyllobates frogs of that region.
Lovely Poison Frog (Phyllobates lugubris)
The lovely poison frog (Phyllobates lugubris) is a species of frog in the Dendrobatidae family. It is found in Costa Rica, Nicaragua, and Panama. Its natural habitats are subtropical or tropical, moist, lowland forests, rivers, plantations , and heavily degraded former forest. It is threatened by habitat loss.
Blue Poison Dart Frog (Dendrobates azureus)
Dendrobates azureus is a species of poison dart frog found in the forests surrounded by the Sipaliwini savannah, which is located in southern Suriname and northern to central Brazil. Dendrobates azureus is widely known as the blue poison dart frog or by its Tirio Indian name, okopipi. Its species name comes from the fact that it is colored azure.
D. azureus is a medium-sized frog that weighs approximately 8 grams. It grows between 3 and 4.5 cm in length and has a typical lifespan of 4–6 years in the wild. Its bright blue skin serves as a warning to predators. Its color is also usually darker around its limbs and stomach.
The glands of poisonous alkaloids located in the skin serve as a defense mechanism to potential predators. These poisons paralyze and sometimes kill the predator. The black spots are unique to each frog, serving as an identification tool. Each foot contains four toes which each have a flattened tip with a suction cup pad used for gripping. This species of frog is also identifiable by a hunch-backed posture.
Physical appearance also differs with the s*x of the animal. Females are larger and about half a centimeter longer than males, but males have larger toes. The tips of the toes in females are round, while males have heart-shaped tips.
Tadpoles vary greatly in appearance from adults. They have a long tail, about 6 mm, with a total length of about 10 mm. They lack legs and have gills instead of lungs.
Strawberry Poison Dart Frog
The strawberry poison frog or strawberry poison-dart frog (Oophaga pumilio) is a species of small amphibian poison dart frog found in Central America. It is common throughout its range, which extends from eastern central Nicaragua through Costa Rica and northwestern Panama.
The species is often found in humid lowlands and premontane forest, but large populations are also found in disturbed areas such as plantations. The strawberry poison frog is perhaps most famous for its widespread variation in coloration, comprising approximately 15–30 color morphs, most of which are presumed to be true-breeding.O. pumilio, while not the most poisonous of the dendrobatids, is the most toxic member of its genus.
Red-backed Poison Frog
The Red-backed Poison Frog (Ranitomeya reticulatus) is a species of frog in the family Dendrobatidae. It is an arboreal insectivorous species, and is the second-most poisonous species in the genus, after R. variabilis. Like many species of small, poisonous frogs native to South America, it is grouped with the poison dart frogs, and is a moderately toxic species, containing poison capable of causing serious injury to humans, and death in animals such as chickens. R. reticulatus is endemic to Peru.
The red-backed poison frog is a moderately toxic dendrobatid, and is the second-most poisonous of the frogs in the Ranitomeya genus. Its toxins are used as the frog’s natural defense mechanisms, making them inedible to many, if not most, of the predators in its natural area.
To advertise its poison and further reduce the risk of injury, the red-backed poison frog displays its brilliant warning colors, especially its red-orange back, for which it is named. Like all dendrobatids, it does not manufacture its poison itself, but rather is theorized to take the toxins from the ants, mites, and beetles on which it lives. It absorbs the insects’ poisons into its body, which is immune to the poison.
The poison is stored in skin glands just beneath the frog’s epidermis. The poison seeps through open wounds and orifices, and, it is believed, through the pores. This defense is especially effective against mammalian and avian predators, and, to a lesser extent, reptilian ones. Amazonian ground snakes have a limited resistance to the poison, and occasionally will attack such frogs.
Ranitomeya reticulata is one of the smaller species of poison dart frogs, hence its inclusion in the “thumbnail” species group. Males can reach approximately 12 mm in length from snout to vent, while the larger females may reach 15 or even 20 mm long. Like all poison dart frogs, R. reticulata are vividly coloured and patterned, which advertises their poison. Red-backed poison dart frogs have black legs with a cobalt or sky-blue mesh pattern, a black belly, and a back that ranges from fiery orange to scarlet in color, hence the common name.
Like all arboreal frogs, reticulata possess suckerlike disks on their toes which makes their grip adhesive. As they are very small, they often attempt to advertise their poison by flaunting such colors or by ascending trees to escape from predators. If isolated from any form of escape, reticulata will use their poison as a defense mechanism. Reticulata are more slimy built than many dendrobatids, which combined with their small size, gives them the ability to squeeze into minute hiding places.
Dyeing Dart Frog
Dendrobates tinctorius, also known by the common name dyeing dart frog, is a species of poison dart frog. It is the third largest species, reaching lengths of 50 millimetres (2.0 in). This species is distributed throughout the eastern portion of the Guiana Shield, including parts of Guyana, Suriname, Brazil, and nearly all of French Guiana.
It exists in discrete patches throughout this region, being restricted to “highland” (up to 350 metres (1,150 ft)) areas. While this species can be found at sea level, these individuals have been collected at the base of nearby hills or mountains. The isolation of populations has presumably occurred as a result of the erosion of these highland areas and the seasonal inundation of the inter-patch areas.
The species encompasses a great diversity of color and patterning variants. Some batrachologists suspect that some of these are actually different species.
The specific name tinctorius comes, however, not from the variety of colors, but from the way some indigenous tribes use the frogs. They rub them on the skin of young parrots, and the toxifying of the bird’s skin causes them to grow feathers of different colors.
Giant Leaf Frog
The Giant leaf frog (Phyllomedusa bicolor) is a hylid frog found throughout the Amazon Rainforest of northern Bolivia, western and northern Brazil, south-eastern Colombia, eastern Peru, southern and eastern Venezuela, and the Guianas. Locally, it also occurs in riverine forest in the Cerrado. This species is now jeopardized by biopiracy because it produces a waxy secretion that may have medicinal uses against AIDS, cancer and other diseases.
The Matses and Mayoruna people apply the poison of the frog to self-inflicted burns in order to enter an altered state of consciousness. The poison has been reported to produce a variety of effects ranging from stimulation, to sedation, anorexia, and hallucinations. The poison contains dermorphin and deltorphin which act on opioid receptors.
Some of the components isolated from the waxy secretion have been patented in the past, but none of those patents have led to successful products yet.
The Giant Leaf Frog is nocturnal. As in several other species of frogs, the eggs are laid in a leaf-nest above a forest pool. When they hatch, the tadpoles fall into the water where they continue the development into adult frogs.