Despite its size, the large humpback whale can catch small fish by 'stalking' them. American and Italian biologists describe this this week in the scientific journal PNAS .

Humpback whales swim as fast as a man jogs and their prey, small fish, is shy and can quickly shoot away when a large hungry animal arrives. Biologists therefore wanted to know how the animals succeed in collecting food.

Humpback whales feed themselves by shooting themselves at a plaice, opening their mouths and sucking a large sip of water containing their prey. Then they only spit out the water and hold their prey in their mouths, to then swallow it.

To find out what these small fish, such as anchovies, react to, the animals were observed in a laboratory. They were shown a dot that grew larger and larger to imitate an approaching predator. This looked at how long it takes for the animals to flee.

Based on this, the biologists discovered that the fish only fled the moment the humpback whistle opened to swallow the plaice. However, the moment the mouth opens, it is already too late for most fish.

The scientists conclude from this that humpback whales time exactly when they open their mouths, so that they can finish their meals too quickly. They 'sneak' at their prey.