Kalimantan barburula [1] ( lat. Barbourula kalimantanensis ) is one of two species of the genus Barburula , which is found in the western part of the island of Kalimantan (Borneo). This is the only hitherto known species of frogs that does not have lungs [2] (although the absence of lungs is also known among representatives of the orders Tailed amphibians ( salamanders of the Plethodontidae family) and Legless amphibians (species Atretochoana eiselti ).
| Kalimantan Barbourula |
| Scientific classification |
|---|
| No rank : | Bilateral symmetrical |
| Squad: | Tailless Amphibians |
| Suborder : | Archaeobatrachia |
| View: | Kalimantan Barbourula |
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| International scientific name |
|---|
Barbourula kalimantanensis Iskandar , 1978 |
| Range on about. Kalimantan |
|---|
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| Security status |
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Endangered speciesIUCN 3.1 Endangered : 54444 |
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Content
Kalimantan barbula reaches up to 40 mm in length; color golden brown with small dark spots. The body and head are flattened, on the extremities the skin hangs in folds, which increases its surface and, thus, facilitates skin respiration. The eyes are large, directed forward. This toad secretes a very large amount of mucus over the entire surface of the body, so it is very difficult to hold in your hands [3] .
Kalimantan barbula lives in fast flowing cold mountain rivers and streams in the central part of the island of Kalimantan . Apparently, the loss of lungs has become an adaptation that makes it easier to stay in such an environment: this reduces the buoyancy of the body, and it is easier for the animal to stay in order not to be demolished by the stream of water. In this case, breathing is ensured by gas exchange on the skin: since oxygen dissolves better in cold water than in warm water, and the rapid flow accelerates gas exchange between the skin of the animal and water, this type of adaptation becomes quite acceptable in the environment familiar to the frog [4] . Usually these frogs spend most of the time hiding under the stones at the bottom of the streams, which is facilitated by the flat shape of the body and head; the absence of lungs also facilitates the contraction of the body when the animal is hiding under stones [3] [4] .
The main threat to the species is illegal gold mining by the so-called "mercury method", which destroys and streams with toxic metals the natural mountain streams (the only environment acceptable for this species), as well as deforestation , which negatively affects the water cycle , thus destroying the natural regulation of water flow in mountainous areas [4] .
The Kalimantan barbula was discovered in 1978 by the Indonesian zoologist Jock Iskander, who found it in the Pinoch River, a small tributary of the Kapuas River . This species became the second in the genus Barbourula: until then, the genus included only one species, the Philippine flat- headed frog ( Barbourula busuangensis ) from the Philippine islands of Palawan and Busuanga (a small island north of Palawan) [5] . Over the next thirty years, only one more specimen of the Bornean flat-headed frog was obtained; both specimens were kept intact in the museum. Despite the X-ray , no lungs were found in them; the surgical section was not carried out, given the extreme rarity of the samples [3] .
In August 2007 , an international expedition led by Singaporean zoologist David Bickford, which also included Jock Iskandar, was able to catch 9 frogs in the same area where they were found for the first time. The first of the frogs caught died quickly, although it was planted in a bucket of water, which led researchers to the idea of the presence of some very specific features in the functioning of the organism of this species. Therefore, this and the other 8 copies found during the expedition were delivered to the laboratory, where they were opened. Only then did it turn out that these frogs lack lungs, as well as the larynx and trachea [4] . Moreover, a related species, the Filipino flat-headed frog, has lungs [5] .
The data collected during the 2007 expedition and subsequent laboratory studies of this species were published on May 6, 2008 in the journal Current Biology [6] .
