How This Zombie Foot is Helping Scientists Fight Stingray Strikes

Stingrays regularly cruise the California coastline, but this year they are so abundant they blanket the sea floor like a leathery carpet. That’s because El Niño has brought warmer waters to the West Coast's beaches. California’s Bolsa Chica and Huntington State Beaches reported 3,100 stingray incidents as of August—roughly twice the total for all of 2025.

“Stingray injuries spike with water temperature and especially during El Niño years,” says Chris Lowe, who leads California State University, Long Beach’s Shark Lab. His research team is studying the increase in Southern California’s injury rates over the last four years. “Based on our discussions with lifeguards, injury reports are up for this year at this time,” he says.

Beachgoers, who are similarly descending upon warmer-than-average beaches, have been getting pierced by a small species of stingray called a round ray.

"Round rays like nice, warm, calm water and so do humans,” says Ben Perlman, who runs the STABB (Stingray and Butterfly Biomechanics) Lab, also at California State University, Long Beach. With higher ocean temperatures due to El Niño, “more people are flocking to the beach for all the right reasons, and that's exactly where the round rays are."

Round rays aren’t the only species expanding their habitat as El Niño warms California’s waters. Sea turtles, a whale shark, hammerheads, and mahi-mahi have also been spotted this year. But rays have been the most injurious. That risk may continue into winter—or when ocean temperatures eventually decrease. Water temperatures have been smashing records from prior El Niños. “We are in uncharted territory,” says Nate Jaros, vice president of animal care at the Aquarium of the Pacific in Long Beach.

When waters are warmer, animals that prefer warmer temperatures tend to increase in numbers. “Round rays happen to be one of those species that thrives at the warmer end of that range, so there are just more of them out there,” says Jaros.

And as Earth’s climate warms over the coming years, this year’s marine heat wave may become the norm. Perlman expects to see these rays moving northward as a result.That’s why he’s on a quest to help current and future beachgoers avoid these painful stings.

Perlman leads a group of undergraduate researchers at the STABB lab. The team has investigated the quick mechanics of a stingray’s tail strike and the venom they inject. Now, the lab is wondering how warmer waters might influence their strikes. To test this, last month they deployed two of their go-to tools: a high-speed camera and a silicone foot connected to a wooden pole. To glean insights, they watch footage of the foot slowly lowering into a tank. It steadies, readies, and then—stomp. The foot lands on its target, a stingray hidden in the sand. The zombie-styled foot, purchased from a Spirit Halloween store, mimics a human foot walking through the shallow waters of the nearby coastline.

Perlman is comparing how they react in water that’s 54°F to 56°F, typical during winter, to 68°F to 72°F, temperatures more common during in summer. More tests are needed to show a clear pattern, but Perlman thinks higher temperatures result in harder hits. "If the water's warmer, they could presumably contract their muscles a little bit faster, and that should potentially translate to a faster tail strike."

When round rays sting, they lash their tail in an arc and slam a barb into their attacker’s body. That barb is covered in a venom-producing sheath, which enters the puncture wound. People who have been stung describe pain as ranging from a bee sting to the worst pain they have ever experienced. The most effective treatment is to put the sting in a bag of hot water, which slowly breaks down the venom over the course of an hour.

Using his lab observations, Perlman is working with a company called DragonSkin to make sting-resistant wetsuit booties. The surfers who might wear them are among those most likely to get injured by rays. In the STABB Lab, machines ram barbs through various iterations of these booties to see how much venom could reach someone’s foot and how much force it takes to get there. “If we can demonstrate that most of the sheath doesn't go through this stingray resistant surf bootie material or even just a regular neoprene surf bootie,” he says, “then that will at least show less venom is getting through.”

In addition to creating ray resistant booties, scientists are also studying where along beaches people tend to get stung. If they know when and where risk is highest, they can issue more precise warnings to visitors.

So far, they know the odds of getting stung are higher at beaches with sandy bottoms or near estuaries, says Felicity Erikkson. She’s a master’s student at CSULB working with Lowe to study lifeguard records of stingray incidents dating back to the 1960s.These records use data from parking lots and overhead photos, but that doesn’t give them an exact visitor count.  “That's one of the hardest parts of looking at stingray injuries. We don't have great data on how many people are using the beach at a certain time,” she says.

In the meantime, Perlman recommends doing the “stingray shuffle,” surfer wisdom that his lab has scientifically verified. Rays bury themselves in the sand and can feel what disturbs the sand around them. By taking tiny, side-swiping steps, a surfer can warn a ray they are coming and reduce their risk of getting stung.

To help both species share the beach, Perlman’s lab will keep collecting rays from the nearby waters and gently stomping on them to understand their secrets. "As much as people fear a [great] white shark,” he says, “it's really the round stingray that you need to be mindful of."