Orcas use high-speed ramming to butcher sunfish off Baja California

When a killer whale butchers a fish it needs to use its head, preferably as a ram and at high-speed.

That's the unique behaviour marine scientist Kathryn Ayres saw as she filmed a small group of orcas (Orcinus orca) slam into one of the world's largest fish off the coast of the Baja California Peninsula in 2024.

In her video, a female orca holds a dead sharptail sunfish (Masturus lanceolatus) by its pronounced rudder-like behind, known as a clavus, in her mouth.

Wounds on the sunfish indicate some of its organs have already been eaten by the orcas.

But in this moment, the female orca doesn't eat the fish, instead she holds it steady as a male comes charging in.

She lets go of the sunfish a second before the male orca collides snout-first into the fish with a water-muffled crunch.

In the water, Dr Ayres repeatedly cries out "Oh my God" as the scene unfolds.

Orcas can reach more than 40km/h in short bursts. The impact in this instance creates an explosion of scales, collagen and viscera.

The cooperative behaviour, which was also captured in a second video in the Gulf of California in late 2025 by herpetologist Héctor Franz, has been described and published today in the journal Frontiers in Ethology.

In both events, senior study author Erick Higuera, a marine biologist and cinematographer, said a mostly intact fish carcass was left behind.

"What is being fragmented is just internal anatomy, organs, flesh, the internal structure," he said.

Recorded observations of the behaviour indicate smaller scraps created by the fish explosion are mostly eaten up by juvenile orcas, while adults prefer to chew on the carcass and extract organs.

The hunting technique adds to a growing catalogue of orca behaviour witnessed in the Gulf of California.

One particular pod from the region, led by a male orca called Moctezuma, are specialist hunters of sharks and rays and are known to herd schools of Mobula rays into tight groups to pick them off one by one.

Orcas blow up sunfish for food and fun

Mr Higuera, from the science and conservation organisation Conexiones Terramar, first witnessed the hold-to-ram behaviour in 2021.

He hypothesised that there were two purposes behind the strategy which were interconnected.

The first was that it could be a more practical way to access the fish's insides compared to just biting.

That was because sunfish, a big disc with two large fins that could weigh more than 2 tonnes and reach 3 metres in length, had outer layers that were dense, rubbery and hard to tear apart.

"So fragmenting the carcass via high-impact ramming breaks the prey into smaller manageable portions," Mr Higuera said.

"Which facilitates ingestion, particularly for juvenile or sub-adult members of the pod … who lack maybe the jaw leverage of adults."

The second part of the equation was social play and learning.

Mr Higuera said big-brained orcas were frequently engaged in object manipulation and cat-and-mouse-like play behaviour.

"[Sunfish] present a low-risk opportunity for the pod, especially sub-adults, to practise strike precision and reinforce social bonds," he said.

"The behaviour provides a practical energetic benefit by facilitating communal feeding while simultaneously serving as a mechanism for play and juvenile learning."

Field biologist John Totterdell from WA's Cetacean Research Centre, who wasn't involved in the study, thought the behaviour was primarily for a feeding purpose.

"These Molids [sunfish] have abrasive skin like sharks, and it's highly likely killer whales prefer to open them up instead of wearing down their teeth," Mr Totterdell said.

"[It's] certainly a highly precise foraging technique these guys have learned."

The technique is another example of how sophisticated killer whale hunting strategies are, according to marine scientist Bec Wellard, from Project ORCA and Curtin University, who wasn't involved in the study.

"The ramming behaviour is really fascinating because it appears to be a coordinated hunting strategy, rather than simply an individual whale striking a sunfish," Dr Wellard said.

"Killer whales are incredibly adaptable predators, and we know that different populations have developed very specialised ways of hunting and processing prey."

"This study highlights just how much we still have to learn about killer whale behaviour … their interactions with unusual prey like sunfish may be much more sophisticated than we currently understand."

Orcas seen 'booping' sunfish in Australia

There's a limited record for how orcas interact with sunfish around the globe.

Forty-two out of 71 orca-sunfish interactions collated in a review, from between 1961 and 2022, involved predation.

There was only one orca involved in the majority of the cases.

There are other instances where the sunfish gets away or the orcas don't eat them.

While sunfish might appear sluggish, marine biologist Marianne Nyegaard, a research associate with Auckland Museum, said they had various evasive manoeuvres believed to be attempts to protect vulnerable body parts like the head and belly.

"The evasive behaviours even include turning themselves upside down at the sea surface so the belly area is above water for the time it takes for the orca to pass," Dr Nyegaard said.

"We do not know how successful these behaviours are … it may be that if an orca is just out to harass a sunfish, these behaviours may help them survive orca harassment."

Dr Wellard said she had seen sunfish swim extremely fast away from research boats in the past in Western Australia.

And, although she hadn't witnessed a predation event by orcas on sunfish, she had seen "booping" interactions.

"From what I've observed during my research voyages, here in WA, killer whales do interact with sunfish at the surface, and I've seen them pushing them around, smacking them and what looks like 'booping' them with their rostrums [snouts]," Dr Wellard said.

"They could potentially represent investigation, play, prey handling, or something else entirely."

"Observations of ramming behaviour and other sunfish versus orca interactions documented worldwide does make me wonder whether some of the interactions we see here in Australia could be part of a broader behavioural repertoire that we haven't yet fully documented."