Bornean Flat-headed Frog

A remarkable and highly unusual frog, one of only two species in its genus and the only frog known to have completely lost its lungs, breathing entirely through its skin — an adaptation linked to life in cold, fast-flowing, oxygen-rich streams. Flattened body and head help it hug the streambed against strong current.

Almost entirely aquatic, rarely if ever leaving the water, and known from only a handful of clear Kalimantan streams. Extremely poorly documented and a genuine scientific rarity rather than a realistic sighting target on a standard visit.