How predatory whales are able to hunt down tiny fish

STANFORD, CALIFORNIA — New research has found that the rorqual whale species, particularly humpback whales, are able to use stealth and deception to prey on tiny fish.

In a Stanford University news release, scientists said they were curious as to why the small fish weren't able to escape from their predator.

The study, published in the journal Proceedings of the National Academy of Sciences, suggests that the precise timing of the whale opening its mouth to engulf the fish allows it to avoid triggering an escape response in them.

When researchers monitored anchovies' escape reaction to a virtual whale, they found that by the time the fish responded to the whale's predatory behavior, it had already expanded its jaw to capture them.

The study suggests that humpback whales wait to open their jaws until they are extremely close to tiny fish in order to engulf them, a method called lunge-feeding.

When whales lunge after tiny fish, their jaws expand to consume a volume of water larger than their own bodies. They then filter out the excess water before swallowing the fish they caught.

This technique allows humpback whales to capture 30 to 60 percent of the school of fish at once.

Scientists did not see the whales doing the same when pursuing other prey such as krill. According to the news release, this is due to krill being less responsive to predators.

David Cade, a researcher involved in the study, explained in the news release that in terms of evolution, lunge-feeding is a comparatively new eating technique for the whales.