The attack came on a beautiful day off the Spanish coast. The terrified crew watched black and white shapes rise from the deep and ram the ship. A pod of orcas - named after the Roman god Orcus: ruler of the dead.

The killer whales pulled off the rudder and then vanished. This behaviour is "completely extraordinary", says biologist Hanne Strager. They have never killed anyone in the wild. But after 500 similar incidents since 2020, there is talk of an "orca uprising".

The rebel leader is called White Gladis, one of fewer than 50 critically endangered Iberian orcas. Scientists believe she was pregnant when she began her campaign and has trained her offspringChildren. to follow her.

And last month, a whale rammed a fishing boat off Shetland, 3,200km from Gibraltar. Expert Conor Ryan says it is "possible" that this "fad" is spreading across Europe. Killer whales are highly social, with "grandmothers" playing a key role in passing on learned behaviour.

But why are they doing it?

"It's a game," says orca specialist Renaud de Stephanis. A three-tonne whale playing with a yacht feels aggressive to those onboard. But "if they wanted to wreck the boat," he argues, "they would break it in 10 minutes."

Play is important for social bonding and learning skills. Individual pods develop their own language, hunting techniques and even fashion. For one summer in 1987, wearing a dead salmon as a hat was all the rage in the northeast Pacific.

But ramming boats is a riskier hobby than fishy headgear. The orcas may hurt themselves and it is unclear what they gain from the encounter. Researcher Alfredo Lopez Fernandez suggests White Gladis may have been "traumatised" in an interaction with a boat. This "triggering event" led her to treat them as a threat.

But do animals seek revenge? A captive killer whale called Tilikum has killed three people. But in the wild, animals mostly avoid humans.

Research shows animal attacks are increasing as their habitat is reduced.¹ Meanwhile, around one million species are on the brink of extinctionCompletely dying out..² Hanne Strager says we will never know why the orcas are hitting boats. But the fact it feels like revenge may say something about our sense of guilt.

Yes: We should be very afraid. For too long, we have mistreated our fellow creatures and taken the natural world for granted. The more harm we cause, the more we should expect animals to fight back.

No: Using the language of revenge and war is dangerous and harmful. Other animals do not share our sense of right and wrong.

Or... This is not animal revenge but it is human guilt. People are ultimately responsible for these encounters and we should do everything we can to lessen our impact on wildlife and the natural world.