Scientists witness sperm whales using excrement to defend themselves against orcas

Orcas are some of the most fearsome predators in nature, known to kill great white sharks, but the sperm whale may well have discovered a way to deter them through "defensive defecation".

That's right, sperm whales could be pooing in order to prevent attacks from killer whales.

This development was observed by a group on a whale watching trip in Bremer Bay, Western Australia [via Discover Wildlife].

Marine biologists on the trip included Jennah Tucker from Naturaliste Charters, who saw something first hand which she described as “mind blowing”.

Sperm whales are 'almost double the size' of their attackers, but orcas are incredible hunters and it seems that the animals could be taking unexpected evasive action to avoid killer whale attacks.

After being hunted by a group of orcas, sperm whales looking to defend a calf released a huge torrent of excrement into the water – which observers initially mistook for a cloud of blood.

iStock

While things were hard to observe given that orcas were diving deep in order to stalk the sperm whales, the events seen on the trip could change perceptions about their behaviour.

“The orcas just took off into a surge,” Tucker said, recounting what the group saw. “You end up with this whitewash coming off their bodies,” she says.

“We were expecting a beaked whale to surface. That’s what this population of orcas is most commonly sighted targeting for prey,” Tucker added.

However, they soon realised it was actually a sperm whale which the group of orcas was targeting.

“A huge tail fluke of a sperm whale appeared,” she recounted, saying that it was a group of four sperm whales and a calf. “They appeared really exhausted and the orcas were swimming in these really tight circles around them.”

At the critical moment in the hunt, Tucker observed a dark cloud rising to the surface which turned out to be excrement.

Sperm whales are roughly the size of orcasiStock

“We initially thought it was blood, because, quite often, with a successful mammal predation you tend to get a big blood bubble. That’s how you know it’s all over.”

The orcas moved away from the group of sperm whales after this – and while more research is certainly needed, as there could have been other reasons for the orcas to withdraw on this occasion – it’s certainly an unexpected development.

“Defecation in sperm whales has previously been observed in association with behaviours that indicate distress. However, it’s not known, for example, whether this is a stress response or an offensive technique to deter predators,” Tucker said.

“Because this type of interaction has been recorded so rarely, there definitely could be other drivers for the orcas’ response.”

Meanwhile, scientists in Canada have discovered what they believe to be a whole new type of orca, and these ones like hunting other whales.

The researchers, based at the University of British Columbia (UBC), identified the group as a new population, after watching them hunt the likes of sperm whales in the open ocean off the west coast of the US.

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