The first frog appeared in the Early Triassic period in Madagascar almost 265 million years ago. Today, these tailless amphibians can be found throughout the diverse climates of the world with the exception of Antarctica and some xeric deserts.
Both frogs and toads belong to the taxonomical order Anura meaning “without tail” and are by far the most diverse and widespread of the three extant amphibian orders. The ITIS (Integrated Taxonomic Information System) current records state that there are 47 families in the Anura order that contains over 6, 000 species. This order is further subdivided into three suborders which are Archaeobatrachia, Mesobatrachia, and Neobatrachia.
There is no taxonomic difference between toads and frogs; however, the term toad is typically employed unofficially to refer to warty frog species that prefer to live on land. While the name frog is reserved for the more aquatic species of anurans that tend to have smooth moist skin and long legs. The family Bufonidae are considered “true toads”; however other families including Bombinatoridae, Alytidae, Pelobatidae, Rhinophrynidae, Scaphiopodidae also contain some toad species.
Darwin’s frog (Rhinoderma darwinii)
Darwin’s frogs also called the Southern Darwin’s frog belong to the Rhinodermatidae family of the Anura. They have a characteristic triangular shaped head and long snouts as well as the appearance and colors – primarily brown, black, dark green of dead leaves, which provides exceptional camouflage allowing them to effectively hide from predators.
The Darwin’s frog is native to Chile and Argentina, where it can be found living in grasslands, forest floors, bogs, and streams. It appears that a mature native forest provides optimum habitat requirements, this environment provides best possible water retention while decreasing soil temperature and providing optimum coverage from predators.
Unfortunately, this species is currently classified as Vulnerable on the IUCN Red List and their decline is due to a range of factors including habitat loss, as well as amphibian diseases such as chytridiomycosis.
Poison Dart Frogs
Poison Dart Frogs, formerly called the poison arrow frog is the name given to a wide range of frog species within the Dendrobatidae family, which encompasses a further three subfamilies known as Colostethinae, Dendrobatinae, and Hyloxalinae. All of which are native to the tropical regions of Central and South America. Their name is given due to natives in these areas traditionally using their toxins to arm to poison their darts.
All species of Poison Dart Frogs are recognizable due to their vibrant colored skins, ranging from bright yellow to red, blue and green. For instance, the Golden poison frog taxonomically named Phyllobates terribilis is a bright yellow frog with black eyes. Interestingly, the brightness of the frog species is associated with the potency of its toxins, which is why the Golden poison frog is one of the most toxic, containing enough potent toxins to cause multiple human fatalities.
A group of frogs broadly named the Glass frog that belongs to the Centrolenidae family was named as such due to their largely transparent abdominals meaning vital organs such as the heart, liver and gastrointestinal tract can all be seen through the skin, as though looking through glass.
Other distinctive characterizes of the Glass frog include a relatively small size – ranges from 3 – 7 cm, as well as a green coloring, with the exception of the transparent skin and forward facing eyes.
The Centrolenidae family contains two subfamilies named Allophryninae and Centroleninae. The majority of species are arboreal (tree dwelling) and found in Central and South America, ranging from southern Mexico to northern Argentina. They tend to lay their eggs among the leaves of the trees they inhabit, which hang over a body of water which the hatching tadpoles will eventually be deposited into.
Goliath Frog (Conraua goliath)
The Goliath frog otherwise named the Goliath bullfrog is the world largest living frog, which can grow to a magnificent 32 cm in length. They have a distinctive dark green coloring and yellow to orange limbs.
The Goliath frog belongs to the Petropedetidae family of which the Goliath belongs to the genus Conrana. The Goliath frog can be found in a very limited habitat in central Africa, primarily in Cameroon and Equatorial Guinea where it lives amongst sandy floors of turbulent rivers.
Unfortunately, due to a range of threats, the Goliath frog is currently listed as an endangered species. This is largely due to hunting for food by natives, the pet trade as well as habitat loss and destruction.
Northern Leopard Frog (Lithobates pipiens)
The Northern Leopard Frog is native to Canada and the United States and due to their impressive size and reputation are the official amphibians of both Vermont and Minnesota.
The Northern Leopard Frog is a relatively large sized frog that can reach lengths of up to 11 cm. Their colors can vary dramatically, ranging from green to brown hues, yet the majority have large dark spots on the limbs, dorsal and backs, typically surrounded by an outer ring.
These frogs can be found in a wide range of habitats including ponds, swamps and marshes. They can be typically be found in bodies of water surrounded by vegetation and in summer prefer to migrate to lawns and grassy areas.
Interestingly, this species of frog is involved in cancer research as it produces a specific type of enzyme that may be a potential treatment for cancer.
Wood Frog (Lithobates sylvaticus)
The wood frogs belong to the Ranidae family and are found throughout North America. They are relatively small species of frog, typically reaching 70 mm in length and the females are considerably larger than the males. Adult wood frogs vary in coloration but tend to range from brown to an orange hue on their bodies and black masking around the eyes.
Wood frogs reside in forest and woodland areas where they are well camouflaged from predators, usually living in a body of water such as swamps and bogs. A key characteristic is their migration behavior as they will often migrate hundreds of meters to breed.
The wood frog has been the focus of intense research in recent years due to their ability to withstand freezing temperatures. It utilizes both urea and glycogen as cryoprotectants that have the ability to limit the damage freezing water crystals have on their tissues.
The tailed frogs are frogs in the genus Ascaphus in which there is only one family named Ascaphidae. This includes the mountain tailed frog (Ascaphus montanus) and the coastal tailed frog (Ascaphus truei).
These frogs have visible tails, which are actually an expansion of the male cloaca, making them a unique family amongst all other frog species. This trait also allows males the ability to perform internal fertilization, which is an advantage since sperm loss is significant in the fast flowing waters they reside in.
The tailed frogs are native to the Northwest United States and British Columbia. They share many characteristics with other primitive frog species, such as additional vertebrae and an absence of vocalization; for instance, the genus in New Zealand known as Leiopelma.
As previously mentioned, a true toad is any anuran belonging to the family Bufonidae. This family encompasses 45 genera and exceeds 500 species. The majority of the species of “true toads” have common features of what is typically referred to as toads, such as wart textured skin and lack teeth.
True toads are found dispersed everywhere in the world, except for the poles and Australia and have a wide range of habitats, including forests and deserts. True toads all have a pair of glands in their heads, these glands referred to as the parotoid glands secrete a poison when the toad in danger. These toxins are collectively termed Bufotoxin but are in fact quite diverse among the different species. For instance, the Psychedelic toad also called the Colorado River toad has been used recreationally by humans. Although it’s essential to remember that other species, such as the Bufo guttatus secretes toxins that are fatal to humans.
Common Midwife Toad (Alytes obstetricans)
The common midwife toad is a species of frog belonging to the family Alytidae and is native to many countries Western and Southern Europe including the United Kingdom, Spain, Belgium, France and the Netherlands.
This Midwife toad can grow up to 5.5 cm, making it a medium-sized anuran and the females are typically larger than the males. It has a substantial build, large head, and typical warty textured skin. The coloration of this species is quite diverse ranging from light grey to dark brown, while the warts are usually red or brown in color.
Similar to other species in the Alytes genus, the males transport their eggs on their backs until the point of hatching, hence why they are termed the “Midwife toad”.
European Fire-bellied Toad (Bombina bombina)
The European Fire-bellied toad is native to Europe and is characterized by their grey to dark brown bodies and red underbellies, responsible for their name. Their skin texture is in keeping with all toads and is moderately covered in warts and black spines, while their eyes are positioned high on their heads, an adaptation for their partially aquatic habitat.
Often a trait of bright colored species – they produce poison, however, it’s not fatal, instead, it acts as an irritant to deter predators, bacteria, and fungi. This species also periodically shed their skin, to do this they inflate themselves and remove the old skin by coughing, which they have then often been observed to ingest.
This species is often confused with the Oriental fire-bellied toad; however, they tend to be much darker in color so are relatively easy to differentiate.
Final Words on Frogs
This article is in no way a comprehensive list of all the different types of frogs in the world, as that would be simply impractical and a never-ending task. For this reason, we have listed and discussed some of the most popular types of frogs out of the 6,000 different species in accordance with the Integrated Taxonomic Information System (ITIS).
For an entire list of all of the currently recorded types of frogs check out the official Taxonomy and Nomenclature for Anura on the official ITIS website.