"Disturbing one animal may affect more than just that individual."
Bat Rays Send Chemical Distress Signals, a First for Cartilaginous Fish
Researchers at Oregon State University have discovered that bat rays produce a chemical cue when frightened, effectively warning other rays of danger. This groundbreaking finding, published in the Journal of Experimental Zoology Part A, marks the first documented case of a chemical disturbance cue in cartilaginous fish—a group that includes sharks and rays. Previously, this type of communication was only known in bony fish.
The Experiment: How the Warning Works
The study's design was elegantly simple, isolating the chemical signal from other senses.
- Three interconnected tanks were used: one "signaler" tank and two "receiver" tanks.
- The tanks were visually and acoustically isolated, but connected by water flow.
- A mock predator (a harmless chase) was introduced into the signaler tank.
The results were immediate and clear. Receiver rays showed distinct behavioral changes—specifically, increased swimming velocity—within seconds of receiving water from the signaler tank. This rapid reaction confirmed that a chemical cue, not sight or sound, was triggering the alarm.
Broader Implications for Sharks and Marine Life
The discovery has significant implications for understanding predator-prey dynamics in the ocean.
- Co-author Taylor Chapple noted that disturbance cues have "never been described in sharks or rays before." This suggests that similar chemical communication systems may exist in other elasmobranchs, including sharks.
- Lead author Joshua Bowman emphasized the broader ecological impact: "Disturbing one animal may affect more than just that individual." The stress of a predator encounter can ripple through a population via these chemical warnings.
Study Details
- The rays were borrowed from the Oregon Coast Aquarium for the research.
- The study was part of Bowman's master's degree thesis at OSU's Big Fish Lab.