Otton frog

The Otton frog (Babina subaspera), is a species of frog in the family Ranidae. It is endemic to the islands of Amami Ōshima and Kakeromajima in the Ryukyu Islands, Japan. Its natural habitats are subtropical or tropical moist lowland forests, freshwater marshes, and intermittent freshwater marshes. Once considered a delicacy as a source of food, it is now threatened by habitat loss through deforestation, and predation by introduced mongooses.

It is one of only two species (the other being Babina holsti) to possess a "pseudothumb" on the forelimbs.[2]

Otton frog
Scientific classification
B. subaspera
Binomial name
Babina subaspera
(Barbour, 1908)

Rana subaspera Barbour, 1908

Physiology and morphology

The Otton frog has been denoted the 'wolverine frog' due to hidden retractable claws, which are sharp and shoot out from under their thumbs. Both male and female Otton frogs have these claws, with male claws being typically longer than those of the females.

Like the five-fingered Hypsiboas rosenbergi frogs of Latin America, the Otton frog has five fingers.[3]


This rare frog uses its switch-blade claws to fight and in mating. Although both sexes have claws, apparently only the males use them, probably to anchor the female to the male during mating.[4]

During fighting, two male Otton frogs wrestle each other until in an embrace. They then impale their opponent on their retractable spikes.[4]


  1. ^ Yoshio Kaneko; Masafumi Matsui (2004). "Babina subaspera". The IUCN Red List of Threatened Species. 2004: e.T19172A8847183. doi:10.2305/IUCN.UK.2004.RLTS.T19172A8847183.en. Retrieved 27 December 2017.
  2. ^ Masayoshi Tokita & Noriko Iwai (2010). "Development of the pseudothumb in frogs". Biology Letters. 6 (4): 517–520. doi:10.1098/rsbl.2009.1038. PMC 2936208. PMID 20147308.
  3. ^ Briggs, Amy (2012-10-19). "The Deadly Thumbs of Japanese Flick Knife Frogs". National Geographic Society (blogs). Retrieved 2016-08-28.
  4. ^ a b Iwai, N. (2013-02-01). "Morphology, function and evolution of the pseudothumb in the Otton frog". Journal of Zoology. 289 (2): 127–133. doi:10.1111/j.1469-7998.2012.00971.x. ISSN 1469-7998.
Babina (frog)

Babina is a genus of frogs in the family Ranidae from southeastern and eastern Asia. Most of the species were originally placed in genus Rana, and Babina has been considered as a subgenus of Rana.

Hairy frog

The hairy frog (Trichobatrachus robustus) is also known as the horror frog or Wolverine frog. It is a Central African species of frog in the family Arthroleptidae. It is monotypic within the genus Trichobatrachus. Its common name refers to the somewhat hair-like structures on the body and thighs of the breeding male.

List of endangered amphibians

As of September 2016, the International Union for Conservation of Nature (IUCN) lists 848 endangered amphibian species. 13% of all evaluated amphibian species are listed as endangered.

No subpopulations of amphibians have been evaluated by the IUCN.

For a species to be considered endangered by the IUCN it must meet certain quantitative criteria which are designed to classify taxa facing "a very high risk of exintction". An even higher risk is faced by critically endangered species, which meet the quantitative criteria for endangered species. Critically endangered amphibians are listed separately. There are 1393 amphibian species which are endangered or critically endangered.

Additionally 1567 amphibian species (24% of those evaluated) are listed as data deficient, meaning there is insufficient information for a full assessment of conservation status. As these species typically have small distributions and/or populations, they are intrinsically likely to be threatened, according to the IUCN. While the category of data deficient indicates that no assessment of extinction risk has been made for the taxa, the IUCN notes that it may be appropriate to give them "the same degree of attention as threatened taxa, at least until their status can be assessed."This is a complete list of endangered amphibian species evaluated by the IUCN.

Ryukyu Islands

The Ryukyu Islands (琉球諸島, Ryūkyū-shotō), also known as the Nansei Islands (南西諸島, Nansei-shotō, lit. "Southwest Islands") or the Ryukyu Arc (琉球弧, Ryūkyū-ko), are a chain of Japanese islands that stretch southwest from Kyushu to Taiwan: the Ōsumi, Tokara, Amami, Okinawa, and Sakishima Islands (further divided into the Miyako and Yaeyama Islands), with Yonaguni the westernmost. The larger are mostly high islands and the smaller mostly coral. The largest is Okinawa Island.

The climate of the islands ranges from humid subtropical climate (Köppen climate classification Cfa) in the north to tropical rainforest climate (Köppen climate classification Af) in the south. Precipitation is very high and is affected by the rainy season and typhoons. Except the outlying Daitō Islands, the island chain has two major geologic boundaries, the Tokara Strait (between the Tokara and Amami Islands) and the Kerama Gap (between the Okinawa and Miyako Islands). The islands beyond the Tokara Strait are characterized by their coral reefs.

The Ōsumi and Tokara Islands, the northernmost of the islands, fall under the cultural sphere of the Kyushu region of Japan; the people are ethnically Japanese and speak a variation of the Kagoshima dialect of Japanese. The Amami, Okinawa, Miyako, and Yaeyama Islands have a native population collectively called the Ryukyuan people, named for the former Ryukyu Kingdom that ruled them. The varied Ryukyuan languages are traditionally spoken on these islands, and the major islands have their own distinct languages. In modern times, the Japanese language is the primary language of the islands, with the Okinawan Japanese dialect prevalently spoken. The outlying Daitō Islands were uninhabited until the Meiji period, when their development was started mainly by people from the Izu Islands south of Tokyo, with the people there speaking the Hachijō language.

Administratively, the islands are divided into Kagoshima Prefecture (specifically the islands administered by Kagoshima District, Kumage Subprefecture/District, and Ōshima Subprefecture/District) in the north and Okinawa Prefecture in the south, with the divide between the Amami and Okinawa Islands, with the Daitō Islands part of Okinawa Prefecture. The northern (Kagoshima) islands are collectively called the Satsunan Islands, while the southern part of the chain (Okinawa Prefecture) are called the Ryukyu Islands in Chinese.


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