Túngara frog

The túngara frog (Engystomops pustulosus; formerly known as Physalaemus pustulosus) is a species of frog in the family Leptodactylidae.[2] Its local Spanish name is sapito de pustulas ("pustulated toadlet").

It is found in Belize, Colombia, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Trinidad and Tobago, Venezuela, and possibly Guyana. Its natural habitats are subtropical or tropical dry forest, dry savanna, moist savanna, subtropical or tropical dry lowland grassland, subtropical or tropical seasonally wet or flooded lowland grassland, freshwater marshes, intermittent freshwater marshes, pastureland, heavily degraded former forest, ponds, and canals and ditches.[1]

Túngara frog
Tungara frog (Physalaemus pustulosus)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Anura
Family: Leptodactylidae
Genus: Engystomops
E. pustulosus
Binomial name
Engystomops pustulosus
(Cope, 1864)

Physalaemus pustulosus (Cope, 1864)


Engystomops pustulosus is a small species of terrestrial frog growing to a length of between 25 and 35 mm (1.0 and 1.4 in).[3]


Engystomops pustulosus is nocturnal, emerging at night to feed on ants and termites and other small invertebrates among the plant litter on the ground. During the breeding season, the males group together at night at temporary pools and call to attract mates. When a female chooses one of the males, amplexus occurs at the edge of the water and the male creates a foam nest in which the eggs are laid; the tadpoles develop in the water and undergo metamorphosis into juvenile frogs in about four weeks.[3]


Female frogs will choose a mate based on the attractiveness of a male’s call. The females are able to recognize the species of the calling male[4] and will preferentially choose to mate with males of the same species. Female preference within her own species is based on complexity of call. Males produce a call that consists of a whine, and can also add up to seven short chuck sounds to their mating call. A call consisting of both a whine and a chuck is considered a complex call. The chuck portion of the call is produced by vibrations of a fibrous mass suspended near the frog's larynx. Larger fibrous masses allow a frog to produce more chucks for each whine.

Females usually prefer complex mating calls (whine and chucks) to simple mating calls.[5] One study found that females will choose a simple call from a member of her own species rather than a complex call from a foreign or different species.[4] Females prefer the mating call of frogs who produce chucks with lower frequencies. One explanation for this preference is that lower frequency calls are found in males of larger size. A larger body size usually correlates with a higher rate of fertilization.[6] If a female finds a male attractive, she will use his mating call, as well as ripples in the water caused by the production of his call, to locate her new mate.

Natural selection plays a role in the varying complexity of a male's advertisement call. Parasites as well as predators, such as the fringe-lipped bat (Trachops cirrhosus), are able to recognize species of frogs based on their mating calls. These predators, like females, prefer complex calls and will use these calls to locate and prey upon male túngara frogs. It is for this reason that males have been found to alternate between complex and simple calls depending on the situation at hand.[6] Males produce complex calls more often when there are other calling males nearby, forming what is known as a chorus. Males that use calling strategies such as this according to cost and benefits of call complexity are able to maximize the possibility of finding a mate and minimize the risk of predation.[7]

When mating, the male frog centers himself atop the female to do rhythmic mixing of a foam-producing solvent released by the female to generate a floating foam nest.[8] The foam nests are resistant bio-foams that protect the fertilized eggs from dehydration, sunlight, temperature, and potential pathogens until the tadpoles hatch. The nest degrades when the tadpoles leave after about four days, otherwise the nest can last for up to two weeks.

The foam is made up of a mixture of novel proteins (called ranaspumins) with unusual surfactant and carbohydrate binding properties that are thought to contribute to the formation and stabilization of the nest structure, resisting dehydration, predation and microbial degradation, whilst being compatible with developing eggs and embryos.[9][10]

One of the proteins present in the foam (ranaspumin-2) has been used by Carlos Montemagno, David Wendell, and Jacob Todd to create an artificial photosynthetic foam. Unlike chemical detergents the protein does not disrupt cell membranes allowing photosynthetic proteins to be positioned in the foam.[11] This new method for producing biofuel won a 2011 Earth Award.


  1. ^ a b Santos-Barrera, G.; et al. (2010). "Engystomops pustulosus". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 February 2014.
  2. ^ Frost, Darrel R. (2014). "Engystomops pustulosus (Cope, 1864)". Amphibian Species of the World: an Online Reference. Version 6.0. American Museum of Natural History. Retrieved 26 February 2014.
  3. ^ a b Leigh, Egbert Giles (1999). Tropical Forest Ecology: A View from Barro Colorado Island. Oxford University Press. p. 34. ISBN 978-0-19-509603-3.
  4. ^ a b Ryan, Michael, and Monica Guerra. (2014). The Mechanism of Sound Production in Tungara Frogs and Its Role in Sexual Selection and Speciation. Current Opinion in Neurobiology 28: 54-59.
  5. ^ Ryan, MJ. 1985. The túngara frog: a study in sexual selection and communication. University of Chicago Press, Chicago.
  6. ^ a b Page, R.A., Bernal, X.E. 2006. Túngara frogs. Current Biology. 23:R979-980
  7. ^ Baugh, A.T, Ryan, M.J. 2010. The relative value of call embellishment in túngara frogs. Behavioral Ecological Sociobiology. 65:359-367.
  8. ^ Dalgetty L. and M. W. Kennedy. (2010). Building a home from foam - túngara frog foam nest architecture and three-phase construction process. Biol. Lett. 6(3) 293-296.
  9. ^ Alan Cooper & Malcolm W. Kennedy, Biofoams and natural protein surfactants, 2010, Biophysical Chemistry, 151: 96-104. doi:10.1016/j.bpc.2010.06.006
  10. ^ Fleming, R. I., C. D. Mackenzie, A. Cooper, and M. W. Kennedy. 2009. Foam nest components of the túngara frog: a cocktail of proteins conferring physical and biological resilience. Proceedings of the Royal Society B: Biological Sciences 276: 1787-1795
  11. ^ Wendell, D.; Todd, J.; Montemagno, C. (2010). "Artificial photosynthesis in ranaspumin-2 based foam". Nano Letters. 10 (9): 3231–3236. Bibcode:2010NanoL..10.3231W. doi:10.1021/nl100550k. PMID 20205454. Free version Archived 2011-07-16 at the Wayback Machine

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Amphibians are ectothermic, tetrapod vertebrates of the class Amphibia. Modern amphibians are all Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arboreal or freshwater aquatic ecosystems. Thus amphibians typically start out as larvae living in water, but some species have developed behavioural adaptations to bypass this. The young generally undergo metamorphosis from larva with gills to an adult air-breathing form with lungs. Amphibians use their skin as a secondary respiratory surface and some small terrestrial salamanders and frogs lack lungs and rely entirely on their skin. They are superficially similar to lizards but, along with mammals and birds, reptiles are amniotes and do not require water bodies in which to breed. With their complex reproductive needs and permeable skins, amphibians are often ecological indicators; in recent decades there has been a dramatic decline in amphibian populations for many species around the globe.

The earliest amphibians evolved in the Devonian period from sarcopterygian fish with lungs and bony-limbed fins, features that were helpful in adapting to dry land. They diversified and became dominant during the Carboniferous and Permian periods, but were later displaced by reptiles and other vertebrates. Over time, amphibians shrank in size and decreased in diversity, leaving only the modern subclass Lissamphibia.

The three modern orders of amphibians are Anura (the frogs and toads), Urodela (the salamanders), and Apoda (the caecilians). The number of known amphibian species is approximately 8,000, of which nearly 90% are frogs. The smallest amphibian (and vertebrate) in the world is a frog from New Guinea (Paedophryne amauensis) with a length of just 7.7 mm (0.30 in). The largest living amphibian is the 1.8 m (5 ft 11 in) Chinese giant salamander (Andrias davidianus), but this is dwarfed by the extinct 9 m (30 ft) Prionosuchus from the middle Permian of Brazil. The study of amphibians is called batrachology, while the study of both reptiles and amphibians is called herpetology.


Engystomops is a genus of frogs in the family Leptodactylidae. They are known commonly as foam frogs or túngara frogs, though the latter name most commonly refers to Engystomops pustulosus. They are native to the Americas from southern Mexico south to the Amazon Basin.This genus was maintained on its own until 1970, when it was merged into Physalaemus, a genus of similar frogs. As studies progressed, there was increasing evidence that Physalaemus was not a monophyletic group; it was made up of several groups. One of those groups consisted of several frogs more closely related to each other than to the rest of the Physalaemus, and they were represented by P. pustulosus, now Engystomops pustulosus. This group was split off in 2005 on the basis of characters such as basic morphology and vocalizations, as well as allozyme and other genetic analysis. The group was given the revalidated name Engystomops. It included two newly described species.

Engystomops pustulatus

Engystomops pustulatus (common name: Guayaquil dwarf frog) is a species of frog in the family Leptodactylidae. It is known with certainty from western Ecuador, whereas the status of Peruvian records is ambiguous as they may refer to an undescribed species or possibly Engystomops puyango. Nevertheless, given that E. pustulatus is now known from Huaquillas in southern Ecuador, near the Peruvian border, it is likely to be found in Peru too.


A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (literally without tail in Ancient Greek). The oldest fossil "proto-frog" appeared in the early Triassic of Madagascar, but molecular clock dating suggests their origins may extend further back to the Permian, 265 million years ago. Frogs are widely distributed, ranging from the tropics to subarctic regions, but the greatest concentration of species diversity is in tropical rainforests. There are over 6,300 recorded species, accounting for around 88% of extant amphibian species. They are also one of the five most diverse vertebrate orders. Warty frog species tend to be called toads, but the distinction between frogs and toads is informal, not from taxonomy or evolutionary history.

An adult frog has a stout body, protruding eyes, anteriorly-attached tongue, limbs folded underneath, and no tail (except in tailed frogs). Frogs have glandular skin, with secretions ranging from distasteful to toxic. Their skin varies in colour from well-camouflaged dappled brown, grey and green to vivid patterns of bright red or yellow and black to show toxicity and ward off predators. Adult frogs live in fresh water and on dry land; some species are adapted for living underground or in trees.

Frogs typically lay their eggs in water. The eggs hatch into aquatic larvae called tadpoles that have tails and internal gills. They have highly specialized rasping mouth parts suitable for herbivorous, omnivorous or planktivorous diets. The life cycle is completed when they metamorphose into adults. A few species deposit eggs on land or bypass the tadpole stage. Adult frogs generally have a carnivorous diet consisting of small invertebrates, but omnivorous species exist and a few feed on fruit. Frog skin has a rich microbiome which is important to their health. Frogs are extremely efficient at converting what they eat into body mass. They are an important food source for predators and part of the food web dynamics of many of the world's ecosystems. The skin is semi-permeable, making them susceptible to dehydration, so they either live in moist places or have special adaptations to deal with dry habitats. Frogs produce a wide range of vocalizations, particularly in their breeding season, and exhibit many different kinds of complex behaviours to attract mates, to fend off predators and to generally survive.

Frogs are valued as food by humans and also have many cultural roles in literature, symbolism and religion. They are also seen as environmental bellwethers, with declines in frog populations often viewed as early warning signs of environmental damage. Frog populations have declined significantly since the 1950s. More than one third of species are considered to be threatened with extinction and over 120 are believed to have become extinct since the 1980s. The number of malformations among frogs is on the rise and an emerging fungal disease, chytridiomycosis, has spread around the world. Conservation biologists are working to understand the causes of these problems and to resolve them.

Illegitimate receiver

An illegitimate receiver is an organism that intercepts another organism's signal, despite not being the signaler's intended target. In animal communication, a signal is any transfer of information from one organism to another, including visual, olfactory (e.g. pheromones), and auditory signals. If the illegitimate receiver's interception of the signal is a means of finding prey, the interception is typically a fitness detriment (meaning that it reduces survival or reproductive ability) to either the signaler or the organism meant to legitimately receive the signal, but it is a fitness advantage to the illegitimate receiver because it provides energy in the form of food. Illegitimate receivers can have important effects on the evolution of communication behaviors.

Mating call

A mating call is the auditory signal used by animals to attract mates. It can occur in males or females, but literature is abundantly favored toward researching mating calls in males. In addition, mating calls are often the subject of mate choice, in which the preferences of one gender for a certain type of mating call can drive sexual selection in a species. This can result in sympatric speciation of some animals, where two species diverge from each other while living in the same environment.

There are many different mechanisms to produce mating calls, which can be broadly categorized into vocalizations and mechanical calls. Vocalizations are considered as sounds produced by the larynx and are often seen in species of birds, mammals, amphibians, and insects. Mechanical calls refer to any other type of sound that the animal produces using unique body parts and/or tools for communication with potential mates. Examples include crickets that vibrate their wings, birds that flap their feathers, and frogs that use an air sac instead of lungs.

Torus semicircularis

The torus semicircularis is a region of the vertebrate midbrain that contributes to auditory perception, studied most often in fish and amphibians. Neurons from the medulla project to the nucleus centralis and the nucleus ventrolateralis in the torus semicircularis, providing afferent auditory and hydrodynamic information. Research suggests that these nuclei interact with each other, suggesting that this area of the brain is bimodally sensitive. In the Gymnotiform fish, which are weakly electric fish, the torus semicircularis was observed to exhibit laminar organization. It receives afferent input, specifically electrosensory, mechanical, and auditory stimuli. In frogs, researchers have studied how neurons in the torus semicircularis prefer certain characteristics of sound differentially. Single neurons fire selectively based on the auditory parameters of a stimulus. Functionally, this can allow members of a species to distinguish whether a call is of the same (conspecific) or a different species. This has been observed to play a role in mate selection. In the Tungara frog, which produces a species-specific mating call, scientists studied responses in the laminar nucleus of the torus semicircularis to various parts of the call. They came to the conclusion that this part of the brain acts as a feature detector (a neuron/neurons that respond to a certain feature of a stimulus) for the parts of the auditory stimulus that are conspecific. From an evolutionary standpoint, research has been conducted in turtles to connect the distribution of calcium-binding proteins in the torus semicircularis among birds and mammals to a common reptile predecessor.

Trypanosoma tungarae

Trypanosoma tungarae is a species of giant trypanosome, a protozoal parasite, which infects the túngara frog and is thought to be transmitted by members of the midge genus Corethrella. It was discovered in 2016.


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