Whales seen disguising themselves as ponds

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Credit: Science

Humpback whales (Megaptera novaeangliae) off the coast of Canada’s Vancouver Island have been caught on film tricking fish into becoming their lunch.

They do it by opening their mouths half out of the water to create what looks like a pool that would make a safe haven from predator seabirds.

Fish that fall for it find themselves quickly clamped between powerful jaws. The stragglers might even be ushered in with a pectoral fin.

Researchers from Canada’s Marine Education and Research Society have been observing the practice since 2011, and they say it is becoming more common. Two humpbacks were confirmed trap feeders at the start of their study, and this had risen to 16 by 2015.

In a paper published in the journal Marine Mammal Science, Christie McMillan and her colleagues say the rapid spread of the technique is significant and may indicate that whales are learning from each other.

Trap feeders seek the same kind of fish in the same kind of places as traditional lunge feeders.

“These results suggest that trap‐feeding may be a culturally transmitted foraging innovation that provides an energetically efficient method of feeding on small, diffuse prey patches,” the researchers write.

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 and “power thrust” into dense balls of young herring, catching the fish by surprise.

Mind you, if you eat – and thus have to catch – up to 2500 kilograms of fish a day, you’re likely to give anything a try.

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