The Deadly Thumbs of Japanese Flick Knife Frogs
by Amy Briggs
The Japanese Otton frog (Babina subaspera) may look harmless, but don’t be fooled by its ordinary green, warty appearance. This frog carries concealed weapons.
A new study has discovered that the Otton frog has sharp retractable claws that shoot out of its thumbs. The rare frog, native to the Amani islands of Southern Japan, uses these “switchblades” to fight and to mate. Conducted by Dr. Noriko Iwai from the University of Tokyo, the new study is published in the Journal of Zoology.
Since 2004, Dr. Iwai has been studying rare frogs to understand the species’ distribution, breeding habits, and range in order to craft sound conservation strategies. Frogs with five digits on their front limbs are uncommon (most have four); the Otton frog’s shares this rare trait with the five-fingered Hypsiboas rosenbergi frogs of Latin America.
“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. Iwai. “The digit encases a sharp spine which can project out of the skin, which fieldwork demonstrates is used for combat and mating.”…
(read more: National Geo) (photos: N. Iwai)