The Rare Frogs Hoofed Like Wolverine

Some kind of a rare frog discovered in Japan appeared to have a weapon like the Wolverine-character in the movie X-Men. The combat-ready spikes which shoot straight from the fingers, like that of a comic book hero, says a Japanese scientist.

The Otton frog is native to southern Japan's Amami islands. (Picture from: http://www.livescience.com/)

The Otton Frog (Babina subaspera) was found in the Amami Islands, southern Japan. Unlike other frogs which have four fingers, Otton has additional structure on his feet, like those of the Hypsiboas rosenbergi frog from Latin America. The discovery, which is published in the Journal of Zoology.

The spike shooting from a male Otton frog's pseudo-thumb. (Picture from: http://www.livescience.com/)

"Why these 'fifth fingers' exist in some species remains an evolutionary mystery, but the extra digit of the Otton is in fact a pseudo-thumb," said Dr Noriko Iwai of the University of Tokyo. "The digit encases a sharp spine which can project out of the skin, which fieldwork demonstrates is used for combat and mating."

Iwai has studied the rare frogs since 2004 in order to understand the species distribution, breeding habits and range -- all factors which will contribute to any conservation strategy, according to a Tokyo statement.

Although the male and female both have sharp nails, but only the male frogs who use it. The male's thumb is bigger than the female. Iwai sure that thumb-dagger evolved as a way for the male to hold the female during mating.

Figure 1. Comparison of prepollex morphology between the Otton frog, Babina subaspera and other anuran species. (a) An adult Otton frog in the field of Amamioshima, Japan. (b) Radiograph of an adult male B. subaspera (snout-vent length ¼ 132.9 mm), focusing on completely ossified prepollical spine (arrowhead). (c) Ventral view of right-hand skeleton stained with Alcian blue (for cartilage) and Alizarin red (for bone) of Glandirana rugosa at stage 45. (d) Ventral view of right-hand skeleton of B. subaspera at the same ontogenetic stage. (Picture from: http://novataxa.blogspot.com/)

"While the pseudo-thumb may have evolved for mating, it is clear that they're now used for combat," Iwai explained in a statement. "The males demonstrated a jabbing response with the thumb when they were picked up, and the many scars on the male spines provided evidence of fighting."

Otton frog combat techniques rather complex, like a wrestling match that lasted long interspersed with spurs jabbing motion into the back of the opponent. They also have to be careful not to stab theirself in the struggle.

The conditions on the Amami islands make combat, and the need for weaponry, a key factor for the frogs mating success. Individuals fight over places to build nests, while the chances of a male finding a mate each night are rare, thus the ability to fight off competitors may be crucial. *** [LIVESCIENCE | ERWIN Z | KORAN TEMPO 4034]
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