They're probably not all seeing an orca and saying, 'time to leave'
Beneath the surface of three isolated tanks at Oregon State University, a quiet revolution in our understanding of ocean life unfolded: bat rays, members of an ancient lineage of cartilaginous fish, were found to warn one another of danger through invisible chemical signals carried on the current. This marks the first documented evidence that sharks, rays, and their kin — long studied as apex predators — possess a form of collective fear, a chemical language that binds individuals into a community of shared survival. The discovery invites us to reconsider not only how these creatures navigate threat, but how deeply the impulse to protect one another runs through the fabric of life in the sea.
- Researchers at Oregon State discovered that a frightened bat ray releases chemical signals into the water that trigger evasion behavior in other rays with no visual or acoustic contact — rewriting what science thought possible in cartilaginous fish.
- The finding disrupts a long-standing gap in marine biology: while bony fish have been known to use chemical alarm systems for decades, sharks and rays were assumed to lack this form of communication entirely.
- The implications ripple outward — white sharks fleeing orca attacks en masse may be responding not to sight, but to a chemical distress broadcast from a single panicked individual.
- Scientists still do not know what the chemical signal is — hormone, metabolite, gill secretion — leaving a critical piece of the puzzle unresolved and future research urgently needed.
- Beyond the laboratory, the discovery carries a conservation warning: disturbing one ray or shark in the wild may send waves of fear through an entire population, with consequences far beyond the single animal in front of you.
In a series of isolated tanks at Oregon State University, graduate researcher Joshua Bowman staged something deceptively simple: he chased a bat ray, simulating a predator attack, while two other rays sat in separate tanks connected only by flowing water. The rays that saw and heard nothing began to swim faster, their bodies shifting into unmistakable postures of escape. The only explanation was chemistry — something the frightened ray had released into the current.
This marks the first time a chemical disturbance cue has been documented in cartilaginous fish, the ancient group that includes rays, sharks, and skates. The behavior is well established in bony fish, but had never been proven in these species. "The animals could not see each other, and they were acoustically isolated," Bowman said, "so our work shows the response was induced by a chemical alert from the frightened ray."
Bowman's deeper curiosity lies with white sharks. Orcas hunt them, and past research has shown white sharks fleeing en masse when orcas appear — even individuals that couldn't have seen the threat. A chemical alarm broadcast by one panicked shark, traveling through the water to others, would explain what no other mechanism has. Bat rays, smaller and more manageable, served as a practical stand-in for testing the hypothesis.
The exact nature of the chemical signal — hormone, metabolite, something shed through skin or gills — remains unknown. But the discovery already carries weight beyond the laboratory. As Bowman noted, disturbing a single animal in the wild may send fear cascading through an entire population. One frightened ray does not suffer alone. It speaks, and the ocean listens.
In a series of tanks at Oregon State University, researchers watched something no one had seen before in sharks or rays: one frightened animal warning others of danger through nothing but chemistry.
Joshua Bowman, a graduate researcher, set up three separate tanks, each holding a single bat ray. The tanks were sealed off from one another—no sight lines, no sound could travel between them. But water could flow from one tank to the next. After the rays settled into their new environment, Bowman chased the ray in the first tank, simulating a predator attack. He didn't harm the animal, just pursued it long enough to trigger genuine fear.
Within seconds, something remarkable happened in the other two tanks. The rays that had seen nothing, heard nothing, began to move differently. They swam faster, their bodies tense with the unmistakable posture of escape. Overhead cameras captured the shift in real time. The only thing connecting these tanks was water—and whatever the frightened ray had released into it.
This discovery marks the first time researchers have documented what scientists call a chemical disturbance cue in cartilaginous fish, the group that includes rays, sharks, and skates. The behavior itself is well understood in bony fish—many species release alarm chemicals when threatened, triggering flight responses in nearby animals. But until now, no one had proven it happened in these ancient, efficient predators. "The animals could not see each other, and they were acoustically isolated, so our work shows the response was induced by a chemical alert from the frightened ray," Bowman said.
The finding opens a window onto how some of the ocean's most formidable hunters actually navigate danger. Bowman's real interest lies with white sharks. Most people don't think of them as prey, but orcas hunt them. Past research has documented white sharks fleeing when orcas appear—but not all of them can see the orca. Something else must be triggering the escape. "They're probably not all seeing an orca and saying, 'Okay, time to leave,'" Bowman noted. "That suggests there's probably some other signal they are responding to."
Bat rays made ideal research subjects. They're smaller and more manageable than white sharks, and the Oregon Coast Aquarium in Newport provided the animals for the study. Because rays are closely related to sharks, understanding how they communicate can illuminate shark behavior too. "Disturbance cues have never been described in sharks or rays, so these findings provide new insights into the communication pathways and behavioral complexities of these critically important marine species," said Taylor Chapple, an associate professor and co-director of the Big Fish Lab.
The exact nature of the chemical signal remains unknown. It could be a hormone, a metabolite, something released through the gills or skin. Future research may identify it. But Bowman emphasized something else: the discovery carries a practical message. "This behavior evolved to help the animals survive in the wild," he said. "But it also serves as a reminder to people that if they disturb these animals, in the wild or in controlled settings, they may be impacting more animals than just the one in front of them." A single frightened ray doesn't just experience fear alone. It broadcasts that fear to every animal downwind, triggering cascades of response across an entire population.
Citações Notáveis
The animals could not see each other, and they were acoustically isolated, so our work shows the response was induced by a chemical alert from the frightened ray.— Joshua Bowman, lead researcher
If they disturb these animals, in the wild or in controlled settings, they may be impacting more animals than just the one in front of them.— Joshua Bowman
A Conversa do Hearth Outra perspectiva sobre a história
Why does it matter that we found this in rays and not just fish?
Because sharks and rays are fundamentally different animals—older, in evolutionary terms, with different sensory systems. If they're using the same chemical warning system as bony fish, it suggests this is a really ancient, reliable strategy. And it changes how we think about shark behavior.
You mentioned white sharks fleeing from orcas. How does this discovery help explain that?
Right now we don't know how a white shark "knows" an orca is nearby if it can't see or hear it clearly. This chemical cue system suggests they might be detecting distress signals from other sharks in the area—essentially, the ocean is passing along warnings through the water itself.
What is the chemical, exactly?
That's the honest answer: we don't know yet. It could be a stress hormone, something released through the gills, something in the mucus. The experiment proved the signal exists and works. Identifying what it actually is—that's the next phase.
Does this change how we should treat these animals in captivity?
It should. If you stress one ray in a tank, you're potentially stressing every ray connected to the same water system. A single disturbance ripples outward in ways we couldn't see before.
Could this apply to other cartilaginous fish—skates, other ray species?
That's a logical next step. The researchers chose bat rays because they're accessible, but the mechanism might be widespread across the whole group. We're probably just at the beginning of understanding how these animals actually talk to each other.