Glass Frog

The glass frog family is a Centrolenidae any of a group of tree frogs found in the New World tropics, some of which have transparent stomachs and chests. The viscera of glass frogs can be seen, and the heart can be seen pumping blood into the arteries and food flowing through the intestines. The translucency of the frogs is a form of camouflage in which an animal's edge blends in with the relative brightness or darkness of its surroundings. The line separating the colour of a frog's skin from the colour of its backdrop is softened by this phenomenon known as edge diffusion. The underside of not all species is a transparent frog. Most glass frogs seem bright green when seen from above. Their patterning mimics glass frog eggs and varies from a uniform green to green with white to yellow dots. Glass frogs have enlarged fingertips that help them climb, allowing them to reside in trees and shrubs near forest streams. There are around 120 species of glass frogs in around ten genera (with most species classified in the genera Centrolene, Cochranella, and Hyalinobatrachium). From tropical lowland forests to mid-elevation mountain forests, they can be found. Adults of most species are tiny, usually 20 to 30 mm (0.8 to 1.2 inches) in total length.

Glass Frogs

Glass frogs belong to the Centrolenidae family of amphibians (order Anura). While the bulk of glass frogs have a lime green background, the belly skin of certain members of this family is a transparent frog and translucent frog. Because the internal viscera, such as the heart, liver, and gastrointestinal system, are visible through the skin, the popular moniker "glass frog" is given. Glass frogs are arboreal, which means they spend large amounts of time in trees and only come out during the mating season.

Classification of Glass Frogs

The "large" Centrolene geckoideum, identified by Marcos Jiménez de la Espada in 1872 based on a specimen obtained in northern Ecuador, was the first Centrolenidae species documented. Different herpetologists (including G. A. Boulenger, G. K. Noble, and E. H. Taylor) described other species in succeeding years, but they were all grouped in with the tree frogs in the genera Hylella of Hyla. Edward H. Taylor suggested the Centrolenidae family in 1945. Most glass frog species were known from Central America in the 1950s and 1970s, mainly from Costa Rica and Panama, where Taylor, Julia F., and Jay M. Savage worked extensively, while just a few species were known from South America. In 1973, John D. Lynch and William E. Duellman published a thorough study of Ecuador's glass frogs, demonstrating that the Centrolenidae family's species richness was concentrated in the Andes. Authors such as William Duellman, John D. Lynch, Pedro Ruiz-Carranza, Juan Rivero, Savage, and José Ayarzagüena contributed later to increase the number of described species, particularly from Central America, Venezuela, Colombia, Ecuador, and Peru. The glass frog weight is between 73 and 180 pounds. The weight of adult males up to 220 pounds, though most average between 73 and 180 pounds.

Guayasamin studied centrolenid evolutionary links, biogeography, and character evolution.

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Glass frogs originated in South America and spread to Central America several times. With numerous gains and/or losses of humeral spines, diminished hand webbing, and total ventral transparency, character evolution seems to be difficult. The glass frogs' taxonomic classification has been a problem. The herpetologists Pedro Ruiz-Carranza and John D. Lynch submitted a proposal for a taxonomic taxonomy of the Centrolenidae based on cladistic principles and defining monophyletic groups in 1991, following a significant revision of the species and taxonomic features. Centrolene, Cochranella, Hyalinobatrachium, and Nymphargus have all been found to be polyphyletic or paraphyletic, and a new taxonomy has just been proposed.

1. Centrolene

The glass frog genus Centrolene belongs to the Centrolenidae family.

Mature males, like the majority of members of this family, have a humeral spine. The distinction between this genus and Cochranella is not entirely clear, and several species that were formerly classified as Centrolenella but are now syTo with Centrolene are now classified as Hyalinobatrachium.

"Giant glass frogs" is the common name for this genus. However, this is just in comparison to the rest of their family, which includes several extremely small species.

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2. Cochranella

Cochranella is a genus of glass frogs belonging to the Centrolenidae family. From Honduras to the Amazonian and Andean cloud forests of Colombia, Ecuador, Peru, and Bolivia, they may be found in Central America. Edward Harrison Taylor was the first to describe Cochranella in 1951. The current delimitation of this genus is based on research published in 2009 by Juan Manuel Guayasamin and colleagues (with some later adjustments). The genus' polyphyly was corrected by these authors, who divided it into numerous separate genera.

The following are the genus' diagnostic characteristics:

(1) There are no humeral spines (small spine present in C. litoralis)

(2) The lobed liver is covered by a transparent hepatic peritoneum and the digestive tract is white (translucent in Cochranella Nola).

(3) The ventral parietal peritoneum is white anteriorly and posteriorly.

(4) The webbing between fingers III-IV is moderate to extensive. 

(5) The bones are green in life.

(6) The dorsum is lavender in preserved specimens.

(7) The vomer and vomerine teeth have a dentigerous process (absent in C. litoralis).

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3. Espadarana

Glass frogs belong to the genus Espadarana.

They inhabit Central America (Honduras, Nicaragua, Costa Rica, and Panama) as well as northern South America (Venezuela, Colombia, and Ecuador). Espadarana is characterized by the presence of large humeral spines in adult males, as suggested by its name. Between the third and fourth fingers, there is some webbing. In preserved individuals, the dorsum is lavender and may have patches. Green bones (in living specimens), a lobed liver with a translucent hepatic peritoneum, and a ventral parietal peritoneum that is white in the anterior portion and transparent in the poster section. The intestines are transparent. Espadarana has vomerine teeth and a quadratojugal bone that expresses with the maxilla in terms of osteology.

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4. Nymphargus

Nymphargus is a glass frog genus that was discovered in 2007. It belongs to the Centrolenidae subfamily.

They may be found on Colombia's, Ecuador's, Peru's, and Bolivia's Andean hills. They are characterized by the absence of webbing between the fingers, the absence of humeral spines in mature males, and the presence of a lobed liver covered by a transparent hepatic peritoneum.

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5. Centroleninae

The Centrolenidae family has two subfamilies: Centroleninae and Centrolenidae. It is found throughout Central America, from Honduras south and east to northern and central South America, in nine species. It now has 117 species as of mid-2015. Centroleninae is classified by genetic and morphological traits that are not visible to the human eye. Males dangle by their feet and fight venter-to-venter; amplexus-like or wrestling on leaves has been observed in several species, which might indicate synapomorphy. Hyalinobatrachinae fighting is thought to be primitive behaviour. Their sister taxon is unclear it might be the genus Ikakogi or the Hyalinobatrachinae subfamily.

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6. Celsiella

Celsiella is a genus of glass frogs that are only found in Venezuela.

It was founded in 2009 and is named after Josefa Celsa Sedaris, a Venezuelan herpetologist who experimented with glass frogs and was nicknamed "Celsi."  The front part of the ventral parietal peritoneum is white, while the posterior part is transparent. The bones are either light green or green in colour. Female Celsiella lay their eggs on the bottom or upper surface of leaves, and male Celsiella call from them. Males appear to defend their eggs, based on circumstantial evidence.

Glass Frog Behaviour and Habitat 

Glass frogs are arboreal, nocturnal, and riparian frogs (living along streams).

Centrolenids are most usually seen in the night amidst the foliage of numerous forest streams and flowing water bodies in neotropical America, where they are active. Glass frogs may be found at altitudes ranging from sea level to over 3,800 metres (McDiarmid, 1983). The species is difficult to spot during the day because it sleeps in the foliage and terrestrial substrate near streams.

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Glass frogs have also been heard singing from vegetation above or near dried-up stream beds, probably expecting the arrival of rains that would deliver the water required for the larvae's survival and growth. The female’s non-breeding behaviours are unknown, though they are likely to specimens Throughout the night hours amid the foliage lining the forest's streams. Females have proved to be far more difficult to locate than calling males in the absence of amplexus. The presence of eggs visible through the translucent dermal layer of the lower abdomen is one means of identifying females in several species. In order to obtain any consistent data, more examination of the frogs about this notion of a feeding phase is required. Glass frogs eat a range of tiny arthropods that may be found in the plants along the stream's banks.

Glass Frog Reproductive Behaviour

In most places, save those without a definite dry season, glass frog species' reproductive activity is heavily influenced by the rainy season, and the species normally reproduce throughout the year. The male centrolenids may be heard making their mating calls along with the stream's vegetation on most humid evenings, especially after a rainfall or even during a drizzle. Mark Hayes discovered that specimens of H. Fleischmann have a substantially higher activity and calling propensity in relative-humidity levels over 93 per cent in a 1982 research.

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Male glass frogs' mating sounds vary per species, although they are often described as single, rising whistles that last less than a second, high-pitched trill, or a succession of brief, high-pitched peeps.

Males will call from certain locations along the stream that have qualities that are conducive to egg depositing right above the stream water. Male centrolenids are territorial and will not accept the presence of other males in direct range to their preferred calling places. The physical conflict between two males over a calling place is rare, although it does happen. Glass frogs' reproductive techniques vary by species, but in general, males call from predetermined locations, and when a female approaches within a few millimetres, the male hops atop her back and commences amplexus.

The female of some species, such as H. Fleischmann, nudges the calling male's side and climbs underneath him. The male then seizes the female and begins amplexus activity (Jacobson, 1985). Amplexus usually lasts several hours or longer, following which the pair will lay between 20 and 30 eggs on a suitable surface overhanging or near stream water if they are successful.

Characteristics of Glass Frogs

Glass frogs are typically tiny, ranging in length from 3 to 7.5cm (1.2 to 3.0). Except for the skin around the bottom portion of the body and legs, which is a transparent frog or translucent frog, they are mostly green in colour. Some green frogs of the genus Eleutherodactylus and some tree frogs of the family Hylidae resemble glass frogs in appearance. Hylid tree frogs, on the other hand, have eyes that face to the side, whereas glass frogs have eyes that face forward. Some green tree frog species (particularly juveniles), such as Hyloscirtus Palmeri and Hypsiboas pellucens, have the translucent abdominal skin of glass frogs, but they also have calcars on their heels, which are absent in any Centrolenidae species.

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When viewed with infrared colour photography, two members of the glass-frog family Centrolenidae (Centrolenella Fleischmann, C. prosoblepon) and the hylid subfamily Phyllomedusinae (Agalychnis moreletii, Pachymedusa technicolour) reflect near-infrared light (700 to 900 nanometers). These arboreal frogs may benefit from infrared reflectivity in both thermoregulation and infrared cryptic colouration.

Distribution of Glass Frogs

The Centrolenidae family includes species found in the Amazon and Orinoco River basins, the Guiana Shield region, southeastern Brazil, and northern Argentina, as well as species found in the Amazon and Orinoco River basins, the Guiana Shield region, southeastern Brazil, and northern Argentina.

Life of Glass Frogs

The majority of glass frogs are arboreal. During the mating season, they may be found along rivers and streams in Central and South America's montane cloud forests, while certain species may also be found in the Amazon and Chocóan rainforests and semi-deciduous forests. Hyalinobatrachium Valerio, or glass frogs, are predatory insects that eat crickets, moths, flies, spiders, and other small frogs.

The eggs are frequently hung from the leaves of trees or bushes that dangle over mountain streams, creeks, and small rivers. One species lays its eggs near waterfalls on rocks. Depending on the species, the way eggs are placed on the leaf varies.

Males frequently use leaves near their egg clutches to make their sounds. These eggs are less scared of humans than those laid in water, however, parasitic maggots from some fly species can damage them. As a result, some glass frogs look after their young.

Tadpoles are elongated, with strong tails and low fins, and are well-adapted to fast-moving water. Some species reside in the canopy outside of the mating season.

Diet of Glass Frogs

The reticulated glass frog, like its red-eye leaf frog companion, is a carnivore. Crickets, moths, flies, spiders, and even smaller frogs make up the majority of their food.

Conclusion

Any group of tree frogs found in the New World tropics is known as glass frog.

The bellies and chests of several animals are transparent. Their patterning resembles glass frog eggs and varies from a uniform green to green with white to yellow dots.

Because their internal viscera, such as the heart, liver, and gastrointestinal tract, can be seen through their skin, they've earned the nickname "glass frog." Most species are small, with adults ranging from 20 to 30 mm (0.8 to1.2 inches) in total length. Most glass frog species were known from Central America in the 1950s and 1970s, mainly from Costa Rica and Panama. Edward H. Taylor suggested the Centrolenidae family in 1945. The glass frog weight is between 73 and 180 pounds. The weight of adult males up to 220 pounds, though most average between 73-180 pounds.