Read our COVID-19 research and news.

Watch humpback whales trick thousands of fish into becoming dinner

The humpback whale has one of the biggest mouths on the planet—and the appetite to match. The bus-size mammals can eat up to 2500 kilograms of fish a day, and a new study reveals one way they snag these huge numbers: They make the fish come to them.

Humpbacks were already known to have a few hunting tricks up their sleeve. They blow bubbles in giant circles around herring to herd them into tightly grouped schools that can be swallowed whole. They also “power thrust” into dense balls of young herring, catching the fish by surprise.

Now, biologists from the Marine Education and Research Society in Port McNeill, Canada, have added a new skill to this repertoire. When seabirds like auklets or murres dive into the water to catch herring, whales off the northeast coast of Vancouver Island in Canada open their mouths half out of the water to make small ponds. Many of the fish mistake the artificial pools as refuges, and once enough have gathered in the whales’ mouths, the whales clamp their jaws shut on an easy snack. Sometimes they even usher a few stragglers in with their pectoral fins, the researchers report in Marine Mammal Science.

The scientists first observed this behavior in a humpback whale in 2011. Since then, they have observed more than 20 individuals doing it. The rapid spread of the technique, often among whales that spend a lot of time together, may indicate that the giant mammals are learning it from each other—possibly as a form of culture, the researchers say. And this, in turn, may help the whales learn new feeding strategies to adapt to future shifts in climate or food availability.