The tentacles of the massive cephalopod left golf ball-size suction marks on the skin of the shark, a seven-foot oceanic whitetip.
This is the first scientific evidence ever found of a shark interacting with a giant squid or any other similarly large species of squid, which live at depths of more than a thousand feet, researchers say in a new study.
The epic tussles between deep-diving sperm whales and giant squid are famous, but until now, no one had proof of a shark encountering a huge cephalopod. (Read about giant squid that could be bigger than a school bus.)
It started in summer 2019, when photographer Deron Verbeck noticed a shark off Hawaii’s Kona coast with a railway pattern of white dots on its flank. Knowing that scientists identify sharks based on their scars, he snapped some pictures.
Back on his computer, he zoomed in on the dots and was surprised to see a series of large suction rings.
“I was like, holy crap!” says Verbeck, who posted the photo on Facebook.
Yannis Papastamatiou, a shark ecologist at Florida International University, in Miami, saw the photograph and immediately contacted Verbeck.
“He told me, Pull that thing off the internet! Nobody’s ever seen that before,” Verbeck recalls.
Papastamatiou and colleagues described the apparent interaction in research published this week in the Journal of Fish Biology. They can’t say which species of squid made the marks—there are several squid large enough to have left them—but, Papastamatiou says, “it had to be something pretty big.”
Such discoveries are especially useful for conserving oceanic whitetips, which are critically endangered because of commercial fishing and the shark fin trade. For instance, knowing that whitetips may hunt in deeper waters can help scientists advise policymakers on which part of the ocean to protect.
Unseen battle of the deep
Papastamatiou cautions that it’s difficult to draw conclusions based on a photograph. “My main regret is that we never got to see what happened,” he says.
A scuffle may have broken out if the two predators bumped into each other, but, he speculates, it’s more likely that the shark went after the squid—possibly in pursuit of a meal.
Oceanic whitetips are unfussy when it comes to diet, preying on a number of different fish and smaller squid species. Though whitetips can make deep dives, they mostly hunt near the surface. (Watch a video of a deep-sea squid grappling with an owlfish.)
It’s also possible that the squid started the fight, but study co-author Heather Bracken-Grissom, a biologist at Florida International University, says she knows of no accounts of squid hunting sharks.
“It is more likely this squid was being attacked by the shark and defending itself,” she said in an email, adding that based on the sucker scars left on the shark, the squid’s mantle, its body, was at least 3.2 feet long. (The tentacles of such a squid could increase its length by some 27 feet.) The white dots are likely smaller suction scars, from the narrower part of the tentacles.
Grace Casselberry, a doctoral candidate in marine science at the University of Massachusetts Amherst, who was not involved in the study, says she’s never heard of sharks clashing with large squid before, nor seen suction marks on a shark. (Read: How big can a squid really get?)
While it’s common to see sharks bearing scars, “it’s not common to be able to figure out what actually caused this,” she says. “This is a really cool interaction to be able to document just through markings on the skin.”
Calamari at the "white shark café"
The research may unveil other shark mysteries.
Shaili Johri, a postdoctoral research fellow at the Hopkins Marine Station of Stanford University, in California, has long wondered why great white sharks hang out in an apparently empty part of the ocean she and colleagues call the “white shark café.”
One of their theories is that great whites may be hunting giant squid in the deep water.
“This finding about oceanic whitetips is significant and goes along with what we are thinking about white sharks,” Johri says. (Read why great whites are still a mystery.)
Johri adds that analyzing DNA from water samples that may contain traces of creatures that have passed through or live in the area could reveal what species of squid are in that part of the ocean, narrowing down the potential victim (or culprit) in this skirmish.
What this shark-squid encounter highlights “is how three-dimensional the ocean is,” Casselberry says. “We don’t always think about how species that occupy different depths interact.” (See photos of deep-sea creatures.)
Animals living in surface and deep-sea ecosystems, once thought relatively isolated from one another, may have previously unknown relationships, Papastamatiou adds.
Such unexpected run-ins between sea creatures can illuminate how oceanic food webs are connected—and yield insights as to how to help protect them.