Glassfrogs
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The glass frogs belong to the
amphibian Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...
family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
Centrolenidae (
order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...
Anura), native to the Central American and Colombian 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 In a multicellular organism, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to a ...
, including the heart, liver, and
gastrointestinal tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the Digestion, digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascula ...
, 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 Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...
, 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 have been threatening the survival rates of the family.


Taxonomy

The first described
species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
of Centrolenidae was the "giant" '' Centrolene geckoideum'', named by
Marcos Jiménez de la Espada Marcos Jiménez de la Espada (1831–1898) was a Spanish Zoology, zoologist, Herpetology, herpetologist, explorer and writer, born in Cartagena, Spain, although he spent most of his life in Madrid, where he died. He is known for participating i ...
in 1872, based on a specimen collected in northeastern
Ecuador Ecuador, officially the Republic of Ecuador, is a country in northwestern South America, bordered by Colombia on the north, Peru on the east and south, and the Pacific Ocean on the west. It also includes the Galápagos Province which contain ...
. Several species were described in subsequent years by different herpetologists (including G. A. Boulenger, G. K. Noble, and E. H. Taylor), but usually placed together with the
tree frog A tree frog (or treefrog) is any species of frog that spends a major portion of its lifespan in trees, known as an arboreal state. Several lineages of frogs among the Neobatrachia suborder have given rise to treefrogs, although they are not clos ...
s in the genera ''Hylella'' or ''
Hyla ''Hyla'' is a genus of frogs in the tree frog family Hylidae. As traditionally defined, it was a wastebasket genus with more than 300 species found in Europe, Asia, Africa, and across the Americas. After a major revision of the family, most of t ...
''. The family Centrolenidae was proposed by Edward H. Taylor in 1945. Between the 1950s and 1970s, most species of glass frogs were known from
Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...
, particularly from
Costa Rica Costa Rica, officially the Republic of Costa Rica, is a country in Central America. It borders Nicaragua to the north, the Caribbean Sea to the northeast, Panama to the southeast, and the Pacific Ocean to the southwest, as well as Maritime bo ...
and
Panama Panama, officially the Republic of Panama, is a country in Latin America at the southern end of Central America, bordering South America. It is bordered by Costa Rica to the west, Colombia to the southeast, the Caribbean Sea to the north, and ...
, where Taylor, Julia F., and Jay M. Savage extensively worked, and just a few species were known to occur in
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...
. In 1973, John D. Lynch and William E. Duellman published a large revision of the glass frogs from Ecuador, showing the species richness of Centrolenidae was particularly concentrated in the
Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...
. Later contributions by authors such as Juan Rivero, Savage, William Duellman, John D. Lynch, Pedro Ruiz-Carranza, and José Ayarzagüena increased the number of described taxa, especially from Central America,
Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...
,
Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...
,
Ecuador Ecuador, officially the Republic of Ecuador, is a country in northwestern South America, bordered by Colombia on the north, Peru on the east and south, and the Pacific Ocean on the west. It also includes the Galápagos Province which contain ...
, and
Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...
. The evolutionary relationships, biogeography, and character evolution of centrolenidae were discussed by Guayasamin et al. (2008) Glass frogs originated in South America and dispersed multiple times into Central America. Character evolution seems to be complex, with multiple gains and/or losses of humeral spines, reduced hand webbing, and complete ventral transparency. Researched by Santiago (2009), evolution and speciation on glass frogs has shown that ecological gradient and isolation have a role in speciation and divergence in glass frogs by comparing glass frogs Mitochondrial DNA. Glass frogs have expanded from the Guiana shield to other rainforest and diversified further. They evolved to be able to survive and fit in with their environment. The taxonomical classification of the glass frogs has been problematic. In 1991, after a major revision of the species and
taxonomic 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme of classes (a taxonomy) and the allocation ...
characters, the herpetologists Pedro Ruiz-Carranza and John D. Lynch published a proposal for a taxonomic classification of the Centrolenidae based on
cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...
principles and defining
monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...
groups.Ruíz-Carranza, P.M. and J. D. Lynch. 1991. Ranas Centrolenidae de Colombia I: propuesta de una nueva clasificación genérica. Lozania, 57, 1–30. That paper was the first of a series of contributions dealing with the glass frogs from Colombia that led them to describe almost 50 species of glass frogs. The genus ''Centrolene'' was proposed to include the species with a
humeral spine humerus, Humeral spines are ventrolateral extensions of the humerus, humeral crista ventralis. These structures are present in the humerus of some frogs (anura (frog), anurans). The majority of anura (frog), anuran species that present humeral spi ...
in adult males, and the genus '' Hyalinobatrachium'' to include the species with a bulbous liver. However, they left a heterogeneous group of species in the genus '' Cochranella'', defined just by lacking a
humeral spine humerus, Humeral spines are ventrolateral extensions of the humerus, humeral crista ventralis. These structures are present in the humerus of some frogs (anura (frog), anurans). The majority of anura (frog), anuran species that present humeral spi ...
and a bulbous liver. Since the publication of the extensive revision of the Colombian glass frogs, several other publications have dealt with the glass frogs from Venezuela, Costa Rica, and Ecuador. In 2006, the genus '' Nymphargus'' was erectedPDF of the abstract.
/ref> for the species with basal webbing among outer fingers (part of the previous ''Cochranella ocellata'' species group). Four genera (''Centrolene, Cochranella, Hyalinobatrachium, Nymphargus'') have been shown to be poly- or
paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...
and recently a new taxonomy has been proposed (see below).


Classification

The family Centrolenidae is a
clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...
of
anurans A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough skin texture due to ...
. Previously, the family was considered closely related to the family
Hylidae Hylidae is a wide-ranging family of frogs commonly referred to as " tree frogs and their allies". However, the hylids include a diversity of frog species, many of which do not live in trees, but are terrestrial or semiaquatic. Taxonomy and ...
; however, recent
phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...
studies have placed them (and their sister
taxon In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...
, the family
Allophrynidae The Tukeit Hill frogs are three species of frog in the genus ''Allophryne''. Originally erected for the species ''Allophryne ruthveni'', the genus was placed as the only member of the family (biology), subfamily Allophryninae, which was in turn p ...
) closer to the family
Leptodactylidae The southern frogs form the Leptodactylidae, a name that comes from Greek meaning a bird or other animal having slender toes. They are a diverse family of frogs that most likely diverged from other hyloids during the Cretaceous. The family has u ...
. The
monophyly In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent comm ...
of Centrolenidae is supported by morphological and behavioral characters, including: 1) presence of a dilated process on the medial side of the third
metacarpal In human anatomy, the metacarpal bones or metacarpus, also known as the "palm bones", are the appendicular bones that form the intermediate part of the hand between the phalanges (fingers) and the carpal bones ( wrist bones), which articulate ...
(an apparently unique
synapomorphy In phylogenetics, an apomorphy (or derived trait) is a novel Phenotypic trait, character or character state that has evolution, evolved from its ancestral form (or Plesiomorphy and symplesiomorphy, plesiomorphy). A synapomorphy is an apomorphy sh ...
); 2) ventral origin of the musculus flexor teres digiti III relative to the musculus transversi metacarpi I; 3) terminal phalanges T-shaped; 4) exotroph,
lotic River ecosystems are flowing waters that drain the landscape, and include the biotic (living) interactions amongst plants, animals and micro-organisms, as well as abiotic (nonliving) physical and chemical interactions of its many parts.Angelier ...
, burrower/fossorial tadpoles with a
vermiform Vermes (" vermin/vermes") is an obsolete taxon used by Carl Linnaeus and Jean-Baptiste Lamarck for non-arthropod invertebrate animals. Linnaeus In Linnaeus's ''Systema Naturae'', the Vermes had the rank of class, occupying the 6th (and last) ...
body and dorsal C-shaped eyes, that live buried within leaf packs in still or flowing water systems; and 5) eggs clutches deposited outside of water on vegetation or rocks above still or flowing water systems. Several molecular
synapomorphies In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to ...
also support the monophyly of the clade. The taxonomic classification of the Centrolenidae was recently modified. The family now contains two subfamilies and 12 genera.


Genera

* Subfamily Centroleninae ** Genus '' Centrolene'' Jiménez de la Espada, 1872 ** Genus '' Chimerella'' Guayasamin, Castroviejo, Trueb, Ayarzagüena, Rada, Vilá, 2009 ** Genus '' Cochranella'' Taylor, 1951 ** Genus '' Espadarana'' Guayasamin, Castroviejo, Trueb, Ayarzagüena, Rada, Vilá, 2009 ** Genus '' Nymphargus'' Cisneros-Heredia & McDiarmid, 2007 ** Genus ''
Rulyrana ''Rulyrana'' is a small genus of glass frogs. They are found in South America, on the Amazonian slopes of the Andes in Ecuador, Peru, and possibly Bolivia, as well as on the eastern slopes of the Cordillera Central (Colombia), Cordillera Central ...
'' Guayasamin, Castroviejo, Trueb, Ayarzagüena, Rada, Vilá, 2009 ** Genus ''
Sachatamia ''Sachatamia'' is a small genus of glass frogs. They are found in Central America (Honduras, Nicaragua, Costa Rica, Panama) and northern South America (Colombia and northwestern Ecuador) at altitudes below above sea level. The generic name ''S ...
'' Guayasamin, Castroviejo, Trueb, Ayarzagüena, Rada, Vilá, 2009 ** Genus '' Teratohyla'' Taylor, 1951 ** Genus ''
Vitreorana ''Vitreorana'' is a genus of glass frogs that are native to South America, from the Atlantic Forest of Brazil and Argentina to the Amazon rainforest of Colombia and Ecuador and to the Venezuelan Coastal Range and the Guianas The Guianas, ...
'' Guayasamin, Castroviejo, Trueb, Ayarzagüena, Rada, Vilá, 2009 ** Genus incertae sedis *** "''Centrolene''" ''acanthidiocephalum'' (Ruiz-Carranza and Lynch, 1989) *** "''Centrolene''" ''azulae'' (Flores and McDiarmid, 1989) *** "''Centrolene''" ''guanacarum'' Ruiz-Carranza and Lynch, 1995 *** "''Centrolene''" ''medemi'' (Cochran and Goin, 1970) *** "''Centrolene''" ''petrophilum'' Ruiz-Carranza and Lynch, 1991 *** "''Centrolene''" ''quindianum'' Ruiz-Carranza and Lynch, 1995 *** "''Centrolene''" ''robledoi'' Ruiz-Carranza and Lynch, 1995 *** "''Cochranella''" ''duidaeana'' (Ayarzagüena, 1992) *** "''Cochranella''" ''euhystrix'' (Cadle and McDiarmid, 1990) *** "''Cochranella''" ''geijskesi'' (Goin, 1966) *** "''Cochranella''" ''megista'' (Rivero, 1985) *** "''Cochranella''" ''ramirezi'' Ruiz-Carranza and Lynch, 1991 *** "''Cochranella''" ''riveroi'' (Ayarzagüena, 1992) *** "''Cochranella''" ''xanthocheridia'' Ruiz-Carranza and Lynch, 1995 * Subfamily Hyalinobatrachinae ** Genus '' Celsiella'' Guayasamin, Castroviejo, Trueb, Ayarzagüena, Rada, Vilá, 2009 ** Genus '' Hyalinobatrachium'' Ruiz-Carranza & Lynch, 1991 – "True" Glass Frogs * Subfamily incertae sedis **'' Ikakogi'' Guayasamin, Castroviejo, Trueb, Ayarzagüena, Rada, Vilá, 2009 File:Glass frog2.jpg, '' Cochranella albomaculata'' from Costa Rica File:Glass frog CR.jpg, '' Cochranella granulosa'' from Costa Rica


Camouflage

The evolutionary advantage of a partly clear skin and an opaque back was a mystery, as it did not seem to be effective as camouflage. It was found that the colour of the frog's body changed little against darker or lighter foliage, but the legs were more translucent and consequently changed in brightness. By resting with the translucent legs surrounding the body, the frog's edge appears softer, with less brightness gradient from the leaf to the legs and from the legs to the body, making the outline less noticeable. This camouflage phenomenon, in which the frog's edges are softened to match the relative brightness of its surroundings, is referred to as edge diffusion. Herpetology researchers study the pros and cons of transparency in glass frogs, it was established that the transparency offers more than regular color changes in the skin itself through limited pigments. Experiments with computer-generated images and gelatine models of opaque and translucent frogs found that the translucent frogs were less visible, and were attacked by birds significantly less often. Photographs of the frogs were taken both at nighttime and during the day, results showed little to no visibility of the frogs on any leaves in the daytime or nighttime. It was found in 2022 that these frogs have the ability to conceal red blood cells concentrated inside their livers, increasing transparency when they are vulnerable. While this would cause massive clotting in most animals (including humans), glass frogs are able to regulate the location, density, and packing of red cells without clotting. The findings could advance medical understanding of dangerous blood clotting. This source has a photograph showing frogs that are almost invisible sleeping on a green leaf.


Characteristics

Glass frogs are generally small, ranging from in length. They appear light green in color over most of their bodies, except for the skin along the lower surface of the body and legs, which are transparent or translucent. The glass frog's transparent skin allows an external view of the viscera—the internal organs present in the body's main cavity—making it so observers can witness the frog's internal processes, such as the heart beating and pumping blood through its arteries. Patterning of glass frogs is varied amongst different species, while some appear as a uniform green color, others display spots that range from yellow to white, mimicking the coloration of their eggs. Their digit tips are expanded, allowing them to climb, thus allowing most to live in elevated areas along forest streams, such as trees and shrubs. Glass frogs are similar in appearance to some green frogs of the genus ''
Eleutherodactylus ''Eleutherodactylus'' is a genus of frogs in the family Eleutherodactylidae.Hedges, S. B., W. E. Duellman, and M. P. Heinicke . 2008. New World direct-developing frogs (Anura: Terrarana): molecular phylogeny, classification, biogeography, and c ...
'' and to some tree frogs of the family
Hylidae Hylidae is a wide-ranging family of frogs commonly referred to as " tree frogs and their allies". However, the hylids include a diversity of frog species, many of which do not live in trees, but are terrestrial or semiaquatic. Taxonomy and ...
. However, hylid tree frogs have eyes that face to the side, whilst those of glass frogs face forward. Two members of the glass-frog family Centrolenidae: ''Centrolenella fleischmanni'', now called '' Hyalinobatrachium fleischmanni'', and '' C. prosoblepon'', and of the hylid subfamily
Phyllomedusinae Phyllomedusinae is a subfamily of hylid tree frogs found in the Neotropics commonly called leaf frogs. Formerly, they were often considered as their own family, Phyllomedusidae. The subfamily is considered to be the sister group to the Austral ...
: ''Agalychnis moreletii'' and ''Pachymedusa dacnicolor'', reflect near-infrared light (700 to 900 nanometers) when examined by infrared color photography. Infrared reflectance may confer adaptive advantage to these
arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...
frogs both in thermoregulation and infrared cryptic coloration. An endangered species of glass frog found in Peru was compared to the N. mixomaculatus species and the following results were recorded: no humeral spine, no webbed fingers between II and III, finger I shorter than II, no vomerine teeth, no ulnar and tarsal tubercles or folds, no white pigment in the visceral or hepatic peritonea, and differing coloration and spots.


Lifecycle


Mating

Mating begins by the call of a male tree frog, who is perched either on the underside or top of a leaf over a lake edge or a stream. Once a female has responded to the male's call, mating begins on the leaf in the amplexus physical position, in which the male wraps his arms around the female and attaches himself to her back. Once the physical mating process has concluded, the female produces her eggs onto the leaf before departing, leaving the male to defend the newly-laid eggs against predators. Centrolenidae is a species that has long-term parental care, males guard the clutch for various days after the eggs are laid. Environmental aspects also play into the amount of time the male glass frog tends to the young, such as rainfall or wind. Female post-oviposition care is most often based on body conditions, whether or not she is able to fend for herself will tell how long after her eggs are laid that she will remain by the clutch. Males will occasionally call for and mate with other females on the same leaf, establishing a multitude of different developmentally-staged egg clutches to guard.


Tadpoles

Once the tadpoles, the frog aquatic larval stage, have been hatched, they fall from their original position on the leaf into the water below. When living in the water the tadpoles feed on the
leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall, or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that has fallen to the ground. This detritus or dead organic material and its constituen ...
and streamside detritus until undergoing metamorphosis to become a froglet.


Conservation


Predators

A main predator on the glass frog in its tadpole stage are "frog flies", which lay their eggs within the frog eggs; after hatching the maggots feed on the embryos of the glass frogs. Glass frog behaviors to avoid predation vary from species to species as well as circumstances. ''Hyalinobatrachium iaspidiense'' was observed having a flattened body posture to avoid predation, after disturbing the frog it propped up into a sitting position. Another male ''H. iaspidiense'' was observed protecting an egg clutch with a body positioning of extending all limbs and lifting its body from the leaf.


Habitat Loss

In addition to predation, glass frog populations are experiencing declines due to habitat loss. Deforestation has been increasing in South America, the natural habitat of the glass frog. This has lead to less tree cover and nowhere for these frogs to go. Furthermore, deforestation may also result in alterations to local climate patterns. As a result, researchers have proposed that these frogs be classified as critically endangered rather than merely endangered.


Protection

All glass frogs are protected under the
Convention on International Trade in Endangered Species Convention may refer to: * Convention (norm), a custom or tradition, a standard of presentation or conduct ** Treaty, an agreement in international law ** Convention (political norm), uncodified legal or political tradition * Convention (meeting ...
(CITES) meaning that international trade (including in parts and derivatives) is regulated by the CITES permitting system.


Distribution

The Centrolenidae are a diverse family, distributed from southern
Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...
to
Panama Panama, officially the Republic of Panama, is a country in Latin America at the southern end of Central America, bordering South America. It is bordered by Costa Rica to the west, Colombia to the southeast, the Caribbean Sea to the north, and ...
, and through the Andes from
Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...
and the island of
Tobago Tobago, officially the Ward of Tobago, is an List of islands of Trinidad and Tobago, island and Regions and municipalities of Trinidad and Tobago, ward within the Republic of Trinidad and Tobago. It is located northeast of the larger islan ...
to
Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...
, with some species in the
Amazon Amazon most often refers to: * Amazon River, in South America * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon (company), an American multinational technology company * Amazons, a tribe of female warriors in Greek myth ...
and
Orinoco River The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers approximately 1 million km2, with 65% of it in Venezuela and 35% in Colombia. It is the List of rivers by discharge, f ...
basins, the
Guiana Shield The Guiana Shield (; ; ; ) is one of the three cratons of the South American Plate. It is a 1.7 billion-year-old Precambrian geological formation in northeast South America that forms a portion of the northern coast. The higher elevations on ...
region, southeastern
Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...
, and northern
Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...
. The biggest threats they have are deforestation, invasive species, pollution, habitat loss and illegal pet trade. These many threats have led to a decline in the population of this species.


Biology

Glass frogs are mostly
arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...
. They live along rivers and streams during the breeding season, and are particularly diverse in montane
cloud forest A cloud forest, also called a water forest, primas forest, or tropical montane cloud forest, is a generally tropical or subtropical, evergreen, Montane forest, montane, Tropical and subtropical moist broadleaf forests, moist forest characteri ...
s of Central and South America, although some species occur also in
Amazon Amazon most often refers to: * Amazon River, in South America * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon (company), an American multinational technology company * Amazons, a tribe of female warriors in Greek myth ...
and Chocóan
rainforest Rainforests are forests characterized by a closed and continuous tree Canopy (biology), canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropi ...
and
semideciduous Semi-deciduous or semi-evergreen is a botanical term which refers to plants that lose their foliage for a very short period, when old leaves fall off and new foliage growth is starting. This phenomenon occurs in tropical and sub-tropical woody s ...
forests. '' Hyalinobatrachium valerioi'' glass frogs are carnivores, their diet mainly including small insects like crickets, moths, flies, spiders, and other smaller frogs. The eggs are usually deposited on the leaves of trees or shrubs hanging over the running water of mountain streams, creeks, and small rivers. One species leaves its eggs over stones close to waterfalls. The method of egg-laying on the leaf varies between species. The males usually call from leaves close to their egg clutches. These eggs are less vulnerable to predators than those laid within water, but are affected by the parasitic
maggot A maggot is the larva of a fly (order Diptera); it is applied in particular to the larvae of Brachycera flies, such as houseflies, cheese flies, hoverflies, and blowflies, rather than larvae of the Nematocera, such as mosquitoes and cr ...
s of some fly species. Some glass frogs show parental care: in many species, glass frog females brood their eggs during the night the eggs are fertilized, which improves the survival of the eggs, while in almost a third of species, glass frog males stay on guard for much longer periods. After they hatch, the
tadpole A tadpole or polliwog (also spelled pollywog) is the Larva, larval stage in the biological life cycle of an amphibian. Most tadpoles are fully Aquatic animal, aquatic, though some species of amphibians have tadpoles that are terrestrial animal, ...
s fall into the waters below. The tadpoles are elongated, with powerful tails and low fins, suited for fast-flowing water. Outside of the breeding season, some species live in the
canopy Canopy may refer to: Plants * Canopy (biology), aboveground portion of plant community or crop (including forests) * Canopy (grape), aboveground portion of grapes Religion and ceremonies * Baldachin or canopy of state, typically placed over an a ...
. The majority of amphibians use cutaneous respiration, or the process of breathing through the skin. Due to the importance of the skin, amphibians are very sensitive to what goes through their permeable skin, the stratum corneum is the main skin barrier which is much thinner than other classes such as mammals or birds. Chemicals and high amounts of elements in water or rainfall may disturb frogs' health and possibly lives.


References

* Kubicki, Brian. Ranas De Vidrio – Costa Rica – Glass Frogs (2007). In Spanish and English. .. * Barnet et al. (2020). ''Imperfect transparency and camouflage in glass frogs. PNAS. 117, 23.''


External links


Amphibian Species of the World



Centrolenidae in AmphibiaWeb

Glassfrogs (Centrolenidae) Project

Centrolenidae in the Tree of Life site

Centrolenidae in ITIS



Centrolenidae in Livingunderworld.org







Various Frog Species
{{DEFAULTSORT:Glass Frog Fauna of the Neotropical realm