Ants are pretty awesome. They clump up into islands to survive floods . They construct ginormous colonies . They even do acrobatics to build bridges (above) -- and now scientists have figured out exactly how.

Army ants construct complex bridges from their own bodies to span crevices as they move across tropical forest floors in Central America, and they adjust their bridges for efficiency based on a cost-benefit trade-off, according to a study published in the Proceedings of the National Academy of Sciences on Monday.

"For the first time, we show how army ants can build long suspended bridges between locations that cannot be spanned by one or two ants only," Simon Garnier, a researcher at New Jersey Institute of Technology and a co-author of the study, said in an email.