Human parents can get into a huge lather about keeping their kids safe. So why should some species of frog be any different? Male Tungara frogs (Engystomops pustulous) will huff and puff and literally kick up a huge clump of foam that serves as a nest to shelter his mate’s eggs. The floating foam nests sound flimsy, but they’re actually incredibly durable–surviving the sun, high temperatures, infections, and parasites for four whole days until the eggs housed inside mature into tadpoles.
While scientists already knew of these foam nests, they didn’t know quite how the frogs made them. Now research (pdf) published in the Royal Society’s journal Biology Letters provides some answers. New footage filmed of an amorous pair of Tungara frogs foaming up a nest in the West Indies shows a carefully calibrated approach to nest-building that’s part yoga, part physics.