ABOVE: From left to right: a tadpole attaches its mouth to the water’s undersurface, initiates bubble-sucking, pinches off an air bubble from the surface, and breathes out a bubble.

Tadpoles use a bubble-sucking behavior to breathe before they are big enough to breach the water’s surface, researchers reported on February 19 in Proceedings of the Royal Society B. Video revealed that tadpoles overcome the obstacle of surface tension by pinching off air bubbles, which are then compressed and forced into the lungs.

“To our knowledge, air-breathing by bubble-sucking has not previously been described for any aquatic vertebrate,” the authors write in the paper. “Given that small tadpoles attempt to breach the water’s surface, but cannot, and that the same tadpoles when larger do breach to breathe, we conclude that bubble-sucking is a larval adaptation to circumvent the physical constraint of surface tension.”...

A gray tree frog (Hyla versicolor) tadpole attaches to the undersurface of the water in preparation for bubble-sucking.
Kurt Schwenk

K. Schwenk, J.R. Phillips, “Circumventing surface tension: tadpoles suck bubbles to breathe air,” Proceedings of the Royal Society B, doi:10.1098/rspb.2019.2704, 2020.

Amy Schleunes is an intern at The Scientist. Email her at aschleunes@the-scientist.com

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