Darwins frog

Rhinoderma darwinii

Darwin's frog , also called the southern Darwin's frog is a rhinodermatid frog native to the forest streams of Chile and Argentina. It was first described by the French zoologist André Marie Constant Duméril and his assistant Gabriel Bibron in 1841, and is named after Charles Darwin, who had previously discovered it in Chile during his world voyage on HMS ''Beagle''.

The most striking feature of this frog is the tadpoles' development inside the vocal sac of the male.
Darwins Frog (Rhinoderma darwinii) from Southern Chile. Darwin’s Frogs (Rhinoderma darwinii) were "discovered" by Charles Darwin on his famous Beagle voyage - folks had known of them prior but this was the first biologist that brought them into focus with regard to western science. Both species of Darwin’s Frogs employ a unique reproductive behavior. Males brood their developing tadpoles inside of their vocal sacs. Female Darwin’s frogs deposit eggs on the damp forest floor of the temperate rainforests of Chile and Argentina. Males fertilize the eggs and remain nearby. Just after the eggs hatch, the male takes the tadpoles into his mouth and manipulates them through a hole below his tongue and into his vocal sac. They will remain there and pass all the way through development and into small frogs in Rhinoderma darwinii. When the babies are ready to live on their won, the male literally “coughs” up fully developed miniatures of the adults. Rhinoderma rufum “coughs” up late stage tadpoles into pools of water. These frogs are endangered. R. rufum has not been observed in over 30 years. Rhinoderma darwinii’s range has declined owing to emergent infectious disease and habitat loss. This individual was photographed in Southern Chile. This is one of the focal species for the collaboration between the San Antonio Zoo, the Austral University, and the National Zoo of Chile in Santiago. The program is the "Chilean Amphibian Conservation Center" and works to develop captive husbandry methods for the most endangered of Chile's frogs. The project also monitors emergent infectious disease in wild populations of amphibians in Chile. Chilean rainforest species,Cycloramphidae,Darwins frog,Darwin’s Frogs,Patagonia,Rhinoderma darwinii,Rhinodermatidae,declining amphibian,emergent infectious amphibian diseases,habitat loss,imperiled species IUCN VU vulnerable,parental care,temperate rainforest endemic,vocal sac brooding

Appearance

Darwin's frog is brown or green with a snout-to-vent length of 2.2 to 3.1 cm . The snout is elongated into a fleshy proboscis which gives the head a triangular shape. The limbs are relatively long and slender. The front feet are not webbed, but some of the toes on the back feet usually are. The dorsal surface is either uniform brown, tan, or reddish brown, uniform pale or dark green, or some combination of brown and green with variable patterning. The ventral surface is black and white, with large blotches.
Darwins Frog (Rhinoderma darwinii) from Southern Chile. Darwin’s Frogs (Rhinoderma darwinii) were "discovered" by Charles Darwin on his famous Beagle voyage - folks had known of them prior but this was the first biologist that brought them into focus with regard to western science. Both species of Darwin’s Frogs employ a unique reproductive behavior. Males brood their developing tadpoles inside of their vocal sacs. Female Darwin’s frogs deposit eggs on the damp forest floor of the temperate rainforests of Chile and Argentina. Males fertilize the eggs and remain nearby. Just after the eggs hatch, the male takes the tadpoles into his mouth and manipulates them through a hole below his tongue and into his vocal sac. They will remain there and pass all the way through development and into small frogs in Rhinoderma darwinii. When the babies are ready to live on their won, the male literally “coughs” up fully developed miniatures of the adults. Rhinoderma rufum “coughs” up late stage tadpoles into pools of water. These frogs are endangered. R. rufum has not been observed in over 30 years. Rhinoderma darwinii’s range has declined owing to emergent infectious disease and habitat loss. This individual was photographed in Southern Chile. This is one of the focal species for the collaboration between the San Antonio Zoo, the Austral University, and the National Zoo of Chile in Santiago. The program is the "Chilean Amphibian Conservation Center" and works to develop captive husbandry methods for the most endangered of Chile's frogs. The project also monitors emergent infectious disease in wild populations of amphibians in Chile. Chilean rainforest species,Cycloramphidae,Darwins frog,Darwin’s Frogs,IUCN VU vulnerable,Patagonia,Rhinoderma darwinii,Rhinodermatidae,declining amphibian,emergent infectious amphibian diseases,habitat loss,imperiled species,parental care,temperate rainforest endemic,vocal sac brooding

Distribution

Darwin's frog is found in Chile and Argentina. In Chile, its range extends from Concepción Province to Palena Province and in Argentina from Neuquén Province and Río Negro Province. It is found in glades and forested areas at altitudes of up to about 1,100 m above mean sea level. It is also found in bogs and near slow-moving streams. It is found in a variety of vegetation types and it appears that a mixture of grassland, mossy areas, coarse woody debris, and young trees and bushes in a mature native forest provides its optimum habitat requirements. Short vegetation increases the retention of water while decreasing the temperature of the soil and provides concealment from predators. The population is fragmented and this frog has poor dispersal ability.Darwin's frog has undergone significant population declines due to habitat loss and degradation, largely from conversion of native forests to tree plantations. The amphibian disease chytridiomycosis, caused by ''Batrachochytrium dendrobatidis'' fungal infection, is also a probable factor, "particularly from the northern part of their historical range". Populations on Chiloé Island were found to be considerably more abundant than on the mainland.

The species is classified as Vulnerable on the IUCN Red List, and a 2013 study reported results of a population survey conducted from 2008–2012, which found the species at just 36 of 223 previously recorded habitat sites, with small populations at those sites. The study recommended IUCN Red List reclassification "at least as Endangered,” and provides a basis of comparison with future population surveys for further reclassification.

Status

Darwin's frog has undergone significant population declines due to habitat loss and degradation, largely from conversion of native forests to tree plantations. The amphibian disease chytridiomycosis, caused by ''Batrachochytrium dendrobatidis'' fungal infection, is also a probable factor, "particularly from the northern part of their historical range". Populations on Chiloé Island were found to be considerably more abundant than on the mainland.

The species is classified as Vulnerable on the IUCN Red List, and a 2013 study reported results of a population survey conducted from 2008–2012, which found the species at just 36 of 223 previously recorded habitat sites, with small populations at those sites. The study recommended IUCN Red List reclassification "at least as Endangered,” and provides a basis of comparison with future population surveys for further reclassification.

Behavior

Darwin's frog feeds on insects and other arthropods. It not only has to hunt, but also needs to hide from its predators. It relies on camouflage to avoid predators, lying on the ground looking like a dead leaf until the predator passes by. Another defensive position is turning on the back and exposing the boldly patterned ventral surface.

The female Darwin's frog lays up to forty eggs among the leaf litter. The male guards them for about three to four weeks until the developing embryos begin to move, and then he ingests the eggs and holds them in his vocal sac. They hatch about three days later and he continues to carry the tadpoles around in his vocal sac where they feed off their egg yolks and secretions produced by the wall of the sac until metamorphosis. At this stage, they hop out of the male's mouth and disperse.

Habitat

Darwin's frog is found in Chile and Argentina. In Chile, its range extends from Concepción Province to Palena Province and in Argentina from Neuquén Province and Río Negro Province. It is found in glades and forested areas at altitudes of up to about 1,100 m above mean sea level. It is also found in bogs and near slow-moving streams. It is found in a variety of vegetation types and it appears that a mixture of grassland, mossy areas, coarse woody debris, and young trees and bushes in a mature native forest provides its optimum habitat requirements. Short vegetation increases the retention of water while decreasing the temperature of the soil and provides concealment from predators. The population is fragmented and this frog has poor dispersal ability.

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Status: Vulnerable | Trend: Down
EX EW CR EN VU NT LC
Taxonomy
KingdomAnimalia
DivisionChordata
ClassAmphibia
OrderAnura
FamilyRhinodermatidae
GenusRhinoderma
SpeciesR. darwinii
Photographed in
Chile