Tracking sharks and dolphins in order to study their habits is tough. Doing so requires researchers to attach some sort of sensor or robot to the animal, but it has to be able to stay on underwater and withstand fast swimming speeds as well as twists, turns and bends. So far, that's been hard to accomplish. But researchers at Beihang University, Harvard University and Boston College have developed a robot that hang on to slick skin underwater and withstand high speeds and sharp movements. They did so by modeling it after an animal that does those things naturally -- the remora.
Cameras attached to blue whales have inadvertently revealed the behaviour of the remora fish that hitch a ride on larger marine animals. Among other things, the footage shows that remoras move around much more than was thought, skimming along just above the skin of whales to minimise drag. "No one else has looked to see what remoras are doing before," says Brooke Flammang at the New Jersey Institute of Technology. There are eight species of remora fish, which have suction discs that they use to cling to larger animals such as whales. The disc is on the on the top of their head, so the remoras cling up on upside down to sharks, mantas and rays. The remoras let go when they see a chance to feed, grab the food and then reattach.
While a scuba diver was swimming off the coast of Hurghada, Egypt, a remora fish mistook him for a shark and tried to latch onto him in the water. In a recently released video of the encounter, the diver is alerted to the fish's presence by the person rolling the camera. The diver looks down, surprised, as the remora swims around him and pecks gently at his diving suit, trying to find a good spot to attach itself to the diver's body. The remora kept up with the diver as he swam through the coral reef, persistently trying to find a place on the diver's body to latch on using the suction cup it has on its head. Enric Sala, a marine biologist and National Geographic Explorer-in-Residence, says he has seen this happen a few times before.
Who are you calling a sucker? Underwater robots could soon hitch rides on sharks and whales thanks to a fish-inspired suction cup that clamps on to shark skin and other surfaces. "Scientists could record data by attaching this robot to animals without hurting them," says Li Wen at Beihang University in China, whose team developed the sucker. It is designed to cling to a moving surface, like a shark, even as it twists and turns at high speed. The design for Wen's robotic suction cup is inspired by the slender sharksucker – a marine fish that attaches itself to sharks, rays and turtles using a sucking disc on its head.