Frogs are some of the most fascinating creatures on our planet. With their vibrant colors, unique calls, and remarkable adaptations, they capture the imagination of nature enthusiasts and casual observers alike. While many people are familiar with common species like the American bullfrog or the poison dart frog, there are countless other extraordinary frogs that remain largely unknown. Here, we explore ten astonishing frog species that you may not have heard of, each with its own remarkable characteristics.
The variety of frogs
Frogs, as a species, are an extraordinary group of amphibians that have thrived on Earth for over 200 million years. With their remarkable ability to adapt, they have colonized a wide range of habitats, from tropical rainforests to arid deserts. In this article, we will explore ten fascinating types of frogs from around the world, each with its own unique adaptations and ecological roles. These creatures are not only important for their environmental contributions but also for the scientific insights they provide into the health of ecosystems and the impact of environmental changes.
Poison Dart Frogs
Poison dart frog (also known as dart-poison frog, poison frog or formerly known as poison arrow frog) is the common name of a group of frogs in the family Dendrobatidae which are native to tropical Central and South America.These species are diurnal and often have brightly colored bodies. This bright coloration is correlated with the toxicity of the species, making them aposematic. Some species of the family Dendrobatidae exhibit extremely bright coloration along with high toxicity — a feature derived from their diet of ants, mites and termites— while species which eat a much larger variety of prey have cryptic coloration with minimal to no amount of observed toxicity. Many species of this family are threatened due to human infrastructure encroaching on their habitats.
These amphibians are often called “dart frogs” due to the aboriginal South Americans’ use of their toxic secretions to poison the tips of blowdarts. However, out of over 170 species, only four have been documented as being used for this purpose (curare plants are more commonly used for aboriginal South American darts) all of which come from the genus Phyllobates, which is characterized by the relatively large size and high levels of toxicity of its members.
Poison Dart Frogs are perhaps the most famous, known for their vivid colors and potent toxins. Native to Central and South American rainforests, these small frogs have a big impact, as their skin secretes powerful alkaloid toxins used by indigenous people to poison the tips of blowdarts.
Habitat
Poison dart frogs are endemic to humid, tropical environments of Central and South America. These frogs are generally found in tropical rainforests, including in Bolivia, Costa Rica, Brazil, Colombia, Ecuador, Venezuela, Suriname, French Guiana, Peru, Panama, Guyana, Nicaragua, and Hawaii (introduced).
Natural habitats include moist, lowland forests (subtropical and tropical), high-altitude shrubland (subtropical and tropical), moist montanes and rivers (subtropical and tropical), freshwater marshes, intermittent freshwater marshes, lakes and swamps. Other species can be found in seasonally wet or flooded lowland grassland, arable land, pastureland, rural gardens, plantations, moist savanna and heavily degraded former forest. Premontane forests and rocky areas have also been known to hold frogs. Dendrobatids tend to live on or close to the ground, but also in trees as much as 10 m (33 ft) from the ground.
Red-Eyed Tree Frogs
Habitat
First identified by herpetologist Edward Cope in the 1860s, the red-eyed tree frog is found in the lowlands and on slopes of Central America and as far north as Mexico. As with other amphibians, red-eyed tree frogs start life as tadpoles in temporary or permanent ponds. As adult frogs, they remain dependent on water to keep their skin moist, staying close to water sources such as rivers found in humid lowland rainforests. Red-eyed tree frogs can be found clinging to branches, tree trunks and even underneath tree leaves. Adults live in the canopy layer of the rainforest, sometimes hiding inside bromeliads.
Red-Eyed Tree Frogs, with their striking red eyes and vibrant green bodies, are the jewels of the Neotropical rainforests. They spend most of their lives in the trees, their coloration a dazzling display to ward off predators. By day, they rest with their eyes closed, blending into the foliage, only to awaken at night to hunt.
Diet
Red-eyed tree frogs are carnivores, feeding mostly on insects. They prefer crickets, flies, grasshoppers and moths. Sometimes, they will eat smaller frogs. For tadpoles, fruit flies and pinhead crickets are the meals of choice.
Threats
Frogs have historically been an indicator species, evidence of an ecosystem’s health or its impending vulnerability. Not surprisingly, the world’s amphibian population has experienced a decline in recent years; research indicates that factors include chemical contamination from pesticide use, acid rain, and fertilizers, the introduction of foreign predators, and increased UV-B exposure from a weakened ozone layer that may damage fragile eggs. Though the red-eyed tree frog itself is not endangered, its rainforest home is under constant threat.
The African Bullfrog
The African bullfrog (Pyxicephalus adspersus), also known as the giant bullfrog or the South African burrowing frog, is a species of frog in the family Pyxicephalidae. It is also known as the pixie frog due to its scientific name. It is found in Angola, Botswana, Kenya, Malawi, Mozambique, Namibia, South Africa, Tanzania, Uganda, Zambia, Zimbabwe, and possibly the Democratic Republic of the Congo. It has been extirpated from Eswatini. It has long been confused with the edible bullfrog (P. edulis), and species boundaries between them, including exact range limits, are not fully understood. Additionally, P. angusticeps of coastal East Africa only was revalidated as a separate species in 2013.
The natural habitat of the African bullfrog is moist to dry savanna, subtropical to tropical dry shrubland, intermittent freshwater lakes, intermittent freshwater marshes, arable land, pastureland, canals, and flooded ditches. It is among the largest anurans on the planet, sixth only to the goliath frog, the helmeted water toad, the Lake Junin frog, the Blyth’s river frog, and the cane toad.
The African Bullfrog is a behemoth, one of the heaviest frogs, known for its voracious appetite. It’s a species that doesn’t shy away from eating anything it can overpower, including other frogs. During the dry season, it burrows underground and enters a state of estivation, emerging with the rains to feed and breed.
Feeding and habits
The African bullfrog is a voracious carnivore, eating insects and other invertebrates, small rodents, reptiles, small birds, fish, and other amphibians that can fit in their mouths. It is also a cannibalistic species—the male African bullfrog is known for occasionally eating the tadpoles he guards,and juveniles also eat tadpoles.An African bullfrog kept at the Pretoria Zoo in South Africa once ate 17 juvenile Rinkhals snakes (Hemachatus haemachatus).
When exposed to dry conditions, they become dormant and may form a cocoon which covers the entire body surface except the external nostrils. The cocoon significantly decreases the rate of evaporative water loss. When it rains, the water softens the cocoon and the frog crawls out.
Glass Frogs
The glass frogs belong to the amphibian family Centrolenidae (order Anura), native to the Central American Rainforests. The general background coloration of most glass frogs is primarily lime green, the abdominal skin of some members of this family is transparent and translucent, giving the glass frog its common name. The internal viscera, including the heart, liver, and gastrointestinal tract, are visible through the skin. When active their blood makes them visible; when sleeping most of the blood is concealed in the liver, hiding them. Glass frogs are arboreal, living mainly in trees, feeding on small insects and only coming out for mating season. Their transparency conceals them very effectively when sleeping on a green leaf, as they habitually do. However, climate change and habitat fragmentation has been threatening the survival rates of the family.
Glass Frogs are named for their translucent abdominal skin, which reveals their internal organs. These delicate creatures are found in the rainforests of Central and South America. Their nearly invisible appearance provides perfect camouflage against the backdrop of rainforest foliage, making them elusive to both predators and researchers.
The Goliath Frog
The goliath frog (Conraua goliath), otherwise known commonly as the giant slippery frog and the goliath bullfrog, is a species of frog in the family Conrauidae. The goliath frog is the largest living frog.[3][4] Specimens can reach up to about 35 centimetres (14 in) in snout–vent length and 3.3 kilograms (7.3 lb) in weight.[5] This species has a relatively small habitat range in Cameroon and Equatorial Guinea.[6] Its numbers are dwindling due to habitat destruction, collection for food, and the pet trade.
The Goliath Frog of West Africa is the largest living frog species. These giants can leap up to 10 feet and weigh as much as a newborn human baby. They’re found near fast-flowing rivers and waterfalls, where they use their powerful legs to navigate the turbulent waters.
Habitat and distribution
The goliath frog is mainly found near waterfalls in Equatorial Guinea and Cameroon. Their habitat is divided into two main seasons: the dry season which occurs from November to April and the rainy season which occurs from May to October.
Due to its large size, the goliath frog has an extremely selective distribution. This species is primarily located in a dense equatorial forest fringe which is somewhat parallel to the coast and surrounded by rivers. The goliath frog has been located in Sanaga Basin (mainly appearing near the Nachtigal cascades and in the Sakbayeme rapids), Kienke Basin, Ntem Basin (mainly being located near the rapids of the Mensolo and Nsana), and Mbía Basin (where it was found to be very abundant in the rapids and cascades). These distribution patterns emphasize its limited environment which tends to have a clear preference for water territories.
American Bullfrog
The American bullfrog (Lithobates catesbeianus), often simply known as the bullfrog in Canada and the United States, is a large true frog native to eastern North America. It typically inhabits large permanent water bodies such as swamps, ponds, and lakes. Bullfrogs can also be found in manmade habitats such as pools, koi ponds, canals, ditches and culverts. The bullfrog gets its name from the sound the male makes during the breeding season, which sounds similar to a bull bellowing. The bullfrog is large and is commonly eaten throughout its range, especially in the southern United States where they are plentiful.
Their presence as a food source has led to bullfrogs being distributed around the world outside of their native range. Bullfrogs have been introduced into the Western United States, South America, Western Europe, China, Japan, and southeast Asia. In these places they are invasive species due to their voracious appetite and the large number of eggs they produce, which has a negative effect on native amphibians and other fauna. Bullfrogs are very skittish which makes capture difficult and so they often become established.
Other than for food, bullfrogs are also used for dissection in science classes. Albino bullfrogs are sometimes kept as pets, and bullfrog tadpoles are often sold at ponds or fish stores.
North America’s American Bullfrog is known for its deep, resonant croak that can be heard over long distances. These large frogs are opportunistic predators, eating anything they can fit into their mouths, including birds, small mammals, and even other frogs.
Tomato Frog
The common name comes from D. antongilii’s bright red color. When threatened, a tomato frog puffs up its body. When a predator grabs a tomato frog in its mouth, the frog’s skin secretes a thick substance that numbs up the predator’s eyes and mouth, causing the predator to release the frog to free up its eyes. The gummy substance contains a toxin that occasionally causes allergic reactions in humans. The allergic reaction will not kill a human and the frog secretes it only when frightened.
The lifespan of the tomato frog can be from 6 to 8 years.When adult, the colors may vary from yellowish orange to deep red. Tomato frogs will reach sexual maturity in 9–14 months. Females are larger than males and can reach 4 inches (10 cm) in length. Males can reach 2 to 3 inches (5 to 7.5) in length. Most females range from reddish-orange to bright dark red. The bellies are usually more yellowish, and sometimes there are black spots on the throat. But males are not as brightly colored but more of a duller orange or brownish-orange. Juveniles are also dull in color and develop brighter coloration as they mature. According to the Smithsonian National Zoo tomato frog’s conservation status has been updated to that of least concern. They breed in the rainy season and are nocturnal. They tend to eat small insects and invertebrates.
Madagascar’s Tomato Frog is an eye-catching species, with females sporting a bright red-orange color that warns predators of their toxicity. When threatened, they secrete a sticky substance that can act as an irritant, deterring would-be attackers.
Surinam Toad
The common Surinam toad, the Suriname toad, or star-fingered toad (Pipa pipa), is a fully-aquatic species of frog, in the family Pipidae, with a widespread range across much of tropical South America and the island of Trinidad. The females of this species are well-known for “incubating” their eggs on their backs, in honeycomb-like depressions directly within the skin, releasing fully-formed froglets after a period of 4–5 months. Pipa pipa is an ambush predator, lying in-wait underwater for prey to inevitably wander too close, swiftly inhaling the unsuspecting creature using suction feeding. Additionally, the Surinam toad’s rather flat body shape, combined with rather dark, dull coloration, serves as effective camouflage in the murky waters they inhabit, perfectly mimicking a dead leaf or piece of rotting wood as they await their next meal.
The Surinam Toad is one of the most unusual frogs, with a flat body and a peculiar method of reproduction. Females carry eggs embedded in the skin of their backs, where they develop into tadpoles and eventually emerge as tiny toads.
Habitat and distribution
The Surinam toad, despite its common name, is actually native to several South American countries; as well as Suriname, it is known from Brazil (primarily the states of Acre, Amazonas, Mato Grosso, Pará and Rondônia), Bolivia, Colombia, Ecuador, French Guiana, Guyana, and Venezuela, in tropical rainforest regions to the east of the Andes. Additionally, a small population may be found in the southwestern corner of the island of Trinidad, just north of Venezuela across the Columbus Channel.Pipa pipa has the largest geographic distribution within its genus.The Surinam toad inhabits warm, acidic, murky and slow-moving to still waterways, including streams, backwaters, ponds and seasonal pools after localized flooding; these rich waters often have a low pH due to a high concentration of organic matter and tannins.
Japanese Tree Frogs
The Japanese tree frog lives in a variety of habitats such as wetlands, forests, rivers, and mountains. They are generally located near vegetation near water sources and forests. They are carnivores that prey on insects and spiders. Their average litter size is around 340–1,500 eggs, and their lifespan is usually around six years. There is an estimated 100 million of these frogs in Japan, but the accuracy is limited due to difficulty in counting.
Japanese Tree Frogs are small, charming amphibians found throughout Japan, Korea, and parts of China. Their melodic calls are a familiar sound in rural areas, signaling the arrival of spring. These frogs have a special place in Japanese culture, often associated with good luck and prosperity.
European Common Frog
The common frog or grass frog (Rana temporaria), also known as the European common frog, European common brown frog, European grass frog, European Holarctic true frog, European pond frog or European brown frog, is a semi-aquatic amphibian of the family Ranidae, found throughout much of Europe as far north as Scandinavia and as far east as the Urals, except for most of the Iberian Peninsula, southern Italy, and the southern Balkans. The farthest west it can be found is Ireland. It is also found in Asia, and eastward to Japan. The nominative, and most common, subspecies Rana temporaria temporaria is a largely terrestrial frog native to Europe. It is distributed throughout northern Europe and can be found in Ireland, the Isle of Lewis and as far east as Japan.
Common frogs metamorphose through three distinct developmental life stages — aquatic larva, terrestrial juvenile, and adult. They have corpulent bodies with a rounded snout, webbed feet and long hind legs adapted for swimming in water and hopping on land. Common frogs are often confused with the common toad (Bufo bufo), but frogs can easily be distinguished as they have longer legs, hop, and have a moist skin, whereas toads crawl and have a dry ‘warty’ skin. The spawn of the two species also differs, in that frog spawn is laid in clumps and toad spawn is laid in long strings.
Lastly, the European Common Frog is a widespread species across the continent. These hardy frogs are known for their mass migrations to breeding ponds in the spring, a phenomenon that signals the awakening of the natural world after winter’s slumber.
the world of frogs is filled with astonishing species that showcase the incredible diversity of life on our planet. From the unique reproductive strategies of Darwin’s frog to the vibrant colors of the Madagascar tomato frog, these amphibians are not only remarkable in their adaptations but also serve as vital indicators of environmental health. Protecting these extraordinary creatures and their habitats is essential for maintaining the biodiversity of our ecosystems. By raising awareness about these lesser-known frog species, we can contribute to their conservation and ensure that future generations can appreciate their beauty and significance.