Like most creatures, hippos do not fancy being followed around by humans as they poop. But a robot boat carefully disguised as a crocodile? Why not.
The Mara River in Kenya, home to 4,000 hippos, is also home to a lot of hippo poop. Scientists have worried that the brown slosh is flowing down river, where bacteria feeding on the waste suck ups all the oxygen in the water, to the harm of local fish.
To actually study the river's water quality, scientists had to get close to the hippos—but not too close. So at the suggestion of a local Maasai guide, the scientists outfitted a little autonomous airboat with sensors, green paint, and a fake crocodile head. The remotely driven crocodile-boat zoomed around the hippos, quietly collecting data on the depth of poop deposits, oxygen levels, water temperature, and more.
But you're probably wondering: What about crocs v. hippos, right? For the most part, the two creatures actually coexist peacefully. The crocodile-boat researchers did, however, have a heart-pounding 30 seconds when a hippo gave chase to the little boat. You can watch the full hippo chase, which starts at about 1:30 below. [Carnegie Mellon via Popular Science]