Ever heard of the remora? It’s a suckerfish famous for hitchhiking on the backs of larger marine animals for food and shelter.
The remora has a funky appearance compared to other fish, which largely comes down to the fact that it has a flattened head covered in ridges. Beneath that strange-looking head are wildly modified dorsal fins that function as suction discs, allowing the remora to hitch a ride on whales.
Although we know this much about the remora, scientists have never observed how remoras behave on their hosts in the wild over any prolonged period of time. But now, thanks to cameras that were appropriately suction-cupped to a whale, scientists have footage of the remora’s mighty sucking power in action.
In a study published in the Journal of Experimental Biology, researchers described how they observed 27 remoras hanging out in 61 different places on the back of a blue whale. However, three specific spots on the blue whale were found to be the most popular: behind the blowhole, around the tiny back dorsal fin, and tucked right above its pectoral fin. Why? Because the drag from the water was reduced by 71 to 84 percent in those spots, allowing the remora to hitchhike with ease. This finding is important because it can help researchers design better trackers for whales and fish that actually stick as the remora does.
The newly captured footage also provided some wild insights into the remora’s behavior while hitchhiking. Apparently, they move about the surface of the whale — which can move much faster than the remora can — by “surfing” and “skimming” along the whale’s skin. The researchers say that closer to the whale is a thin layer of water with over 70 percent less drag than the water directly above it; by surfing in this narrow band and skimming along the surface, attaching and detaching its suction disc as it goes, the remora can move around freely without getting blown away.
“We learned that the remora’s suction disk is so strong that they could stick anywhere, even the tail fluke where the drag was measured strongest, but they like to go for the easy ride,” said Erik Anderson, a biofluid dynamics researcher at Grove City College. “This saves them energy and makes life less costly as they hitchhike on and skim over the whale surface like a NASA probe over an asteroid or some mini-world.”