Few animals in the sea are up to taking on the mighty orca. Like a pack of wolves, a pod of these black-and-white dolphins can team up and tear down large prey like seals, porpoises, blue whales, and great white sharks. Even sperm whales, the largest predators on Earth, are thought to be 'largely helpless' in the face of an orca attack.

Researchers on a tour boat off the southwestern tip of Australia have discovered a secret whale weapon these elusive creatures hide up their sleeves – or, rather, up their bowels – in use against an orca onslaught.

The new footage shows that when sperm whales (Physeter macrocephalus) are threatened by orcas (Orcinus orca) they can shoot a poop slushy into the faces of their attackers. A big, red bomb of explosive diarrhea is apparently like kryptonite for killer whales. And who can blame them?

According to marine biologist Jennah Tucker, one of the orcas positioned behind the sperm whale when it 'let loose' was assaulted by a cloud of liquid feces. As Tucker told ABC News Australia, the orca on the receiving end of the seriously off-putting defense "moved off really suddenly". Others in its pod soon followed suit.

Red Whale Poo
An example of whale poo, tinged red by prey like krill and squid. (izanbar/Getty Images)

The orcas "put on an intense pursuit which showcased their power and elite hunting techniques, allowing them to herd the ocean's largest toothed predator into the shallows," reads a Facebook post from the Naturaliste Charters Bremer Canyon Killer Whale and Pelagic Expeditions.

"But it seemed that today they were no match for the defence tactics of the sperm whales, whose incredibly strong bonds helped them to withstand an attack from the apex of apex predators."

Sperm whales are known to use 'defensive defecation' to their advantage, but this may be one of the first times, if not the first, that a whale's 'poonado' has been observed in use against orcas.

The rare event was recently recounted for Whale Watch Western Australia's website. Tucker and those on board the Naturaliste Charters tour boat had followed the orcas that frequent Bremer Bay, southeast of Perth, for a "solid three hours", while the pod clearly stalked something beneath the waves.

The matriarch of the orca pod, named Cookie, was leading the chase. At some point, she zoomed ahead, and then stopped, waiting for the rest of the pod to catch up.

"[W]e finally could see what she had been moving towards… " reads the online account of the attack.

"… it was a pod of young sperm whales."

As the whales regrouped while keeping a wary eye on the orcas, Cookie "suddenly came flying through the water like a rocket at them all."

As is usual when faced by an orca attack, the sperm whales huddled together in a 'rosette' circle, with their tails pointed outwards and the youngest and most vulnerable member tucked in the middle.

Sperm Whale Rosette
Example of a sperm whale rosette. (Tim Cole/NOAA)

No matter how many times the orcas hurled themselves at the defensive structure, the whales held strong.

Then, something unexpected happened. A big, dark bubble of reddish fluid broke the surface of the ocean near the largest whale in the circle and covered an orca named Wonks, who "peeled away quickly".

Only later when employees were pouring over the footage did they realize this was not blood from the bite of an orca. It was poop. And a lot of it.

Next up for attack was an orca named Shredder. She, too, was met with the same fate as Wonks. The large sperm whale had once again emptied its bowels on its attacker.

Shredder apparently slapped her tail one more time in a way that "seemed to reflect her frustration". Then, the orcas regrouped and left.

The entire battle lasted over an hour.

Preying on the world's largest toothed predator is not unheard of for orcas, but it is thought to be relatively rare. Since at least 1997, however, researchers have argued that this behavior is likely underestimated.

To that point, a study published just this month claims to have found a population of orcas off the west coast of the United States, half a world away, that also prey on sperm whales. It's unknown if these sperm whales also use the defecation defense against their attackers.

"During previous encounters with the Bremer Bay orca and sperm whales we have seen a few halfhearted attempts from the orca to approach/hassle the sperm whales but never with this much focus and intensity before," reads the account on the Whale Watch Australia website.

"We know that today both the orca and sperm whales learnt many lessons from such an intense interaction… "

Wonks and Shredder better hope they never find themselves on the bad side of a sperm whale again.