As wind farms spread across coastal oceans, blacktip sharks can still detect underwater sounds from nearly 250 feet away and turn sharply from the source
A blacktip shark glides through shallow, sunlit waters off Palm Beach County, Florida — unhurried, with nothing visible nearby to disturb it. Then a low-frequency pulse from an underwater speaker nearly 250 feet away cuts through the water. The shark abruptly changes course.
Scientists have long known that sharks use sound to navigate their environment. But direct evidence of how far a free-swimming shark can hear in open ocean — and whether it can pinpoint where a sound originates — has been surprisingly hard to establish. A new study from Florida Atlantic University is starting to fill that gap.
A sense hiding in plain sight
Sharks are famous for acute senses — electroreception, smell, vision — but hearing has received far less scientific attention, at least under natural conditions. Most of what researchers knew about shark acoustics came from tank experiments, which carry a built-in problem: sound bounces off the walls, creating a tangle of reflections that makes it nearly impossible to know what an animal is actually responding to.
That higher frequency sits well outside the known hearing range of sharks, so any reaction would signal that something other than hearing was driving the response.
“It is like being in a house of mirrors,” said Caroline Sullivan, lead author of the new study. That acoustic confusion is exactly why open-ocean testing matters.
Out in open water, the sound environment is far cleaner. Blacktip sharks off Palm Beach County were ideal subjects — they gather in large numbers along the coast each winter, and the clear, shallow water let researchers observe individual animals from above without disturbing them.
How researchers set up the experiment
The team anchored a boat and placed an underwater speaker in the water, letting it drift with the current up to 51 feets from the vessel. That drift was intentional — it reduced the chance that the boat itself would influence shark behavior.
Three bands of low-frequency sound were played: 100–200 Hz, 200–400 Hz, and 400–800 Hz. A fourth sound, at 10 kHz, served as a control. That higher frequency sits well outside the known hearing range of sharks, so any reaction would signal that something other than hearing was driving the response. A drone flew 40 to 50 meters above the water, recording shark movements frame by frame, while calibrated hydrophones measured exact sound levels at different distances.
What the sharks did — and what it reveals
The results were clear. Sharks responded to all three low-frequency ranges and showed zero reaction to the 10 kHz control, confirming that what researchers were measuring was genuinely hearing-based.
Detection occurred at distances up to 74 meters — roughly 243 feet — farther than previously demonstrated in free-swimming sharks. When sharks reacted, they made rapid, sharp turns away from the speaker rather than veering randomly. That oriented response suggests the animals could identify where a sound was coming from, not merely that one existed nearby. More than 70 percent of recorded responses occurred in the acoustic far field, and sharks proved most sensitive to the lowest frequencies, detecting those from greater distances and at lower sound levels.
How sharks hear without a swim bladder
What makes this capability particularly interesting is that sharks lack the gas-filled swim bladder found in many bony fish — a structure that plays a key role in detecting sound pressure for those species. Sharks simply don’t have that option.
Instead, they rely primarily on their inner ears. One key structure is the macula neglecta, a specialized sensory patch thought to detect particle motion — the physical displacement of water molecules as a sound wave passes through. The new findings suggest sharks can pick up this particle motion at considerable distances. As senior author Stephen Kajiura put it, that’s “something we have not previously been able to demonstrate in free-swimming sharks.”
What comes next for shark acoustics research
The immediate question researchers want to answer is how the shark sensory system processes these distant signals. Detecting particle motion from nearly 250 feet away is one thing; the neural and mechanical pathway that makes it possible is another matter entirely.
Broader implications loom as well. Human-generated ocean noise — from shipping traffic, sonar operations, and offshore construction — has grown substantially in recent decades. As wind farms expand across coastal oceans, understanding how that acoustic backdrop affects shark behavior becomes increasingly relevant. Whether chronic noise exposure alters how sharks hunt, navigate, or avoid threats remains an open question. The methodology itself may prove as valuable as the findings, offering a replicable framework applicable to other marine species.
Learn more about this discovery here: C L Sullivan, E R Gerstein, S M Kajiura. Orientation of Blacktip Sharks (Carcharhinus limbatus) to Underwater Sound. Integrative Organismal Biology, 2026; 8 (1) DOI: 10.1093/iob/obag033
Daniel García is an Editor-in-Chief with strong expertise in structural work and engineering principles. He combines this technical foundation with deep knowledge of energy, spatial design, and emerging technologies, bringing a forward-thinking and analytical approach to editorial leadership.
