Bubble-net hunting. It’s a sophisticated technique that humpback whales use to scoop themselves up a tasty mouthful or two of krill, and it’s what’s happening in the photo above, captured by a whale-watching drone from the Marine Robotics and Remote Sensing Lab at Duke University in the USA.
A pair of whales – one seen in the centre of the image, having just surged to the surface to fill its mouth with thousands of litres of water from which it will strain a feast of tiny crustaceans, and the other lurking just above it – have worked together to build a trap. By swimming around in a closing spiral, releasing columns of bubbles through their blowholes at carefully timed intervals, they create a barrier that herds the krill into close quarters with one another. When the time is right, the whales turn and head up through the dense cloud of krill to collect their dinner.
The picture was taken off the Antarctic coast, where the whales spend summer fattening up before heading north to breed in warm, tropical waters.