BLACKTIP SHARKS HEAR DISTANT SOUNDS: WHAT A NEW STUDY REVEALS

The shark is already swimming past when an underwater speaker switches on. It turns abruptly and moves away. Seen from a drone, that change of course becomes a measurable clue: the animal has detected something it cannot see and has information about where it came from.

A 2026 field study shows blacktip sharks responding to low-frequency sound at distances reaching 74 metres. Its importance is more specific than the claim that every shark can hear far more than previously thought. The research strengthens evidence for distant sound detection and directional responses in one species. It does not reveal ultrasonic hearing or establish a universal shark hearing range. Sullivan, Gerstein and Kajiura: original 2026 study

THE STUDY BEHIND THE HEADLINE

Caroline L. Sullivan, Edmund R. Gerstein and Stephen M. Kajiura of Florida Atlantic University published Orientation of Blacktip Sharks (Carcharhinus limbatus) to Underwater Sound in Integrative Organismal Biology on June 30, 2026. The university highlighted the findings on September 24. This is a field experiment with wild sharks, rather than an aquarium test or a new claim based only on anatomy. Sullivan, Gerstein and Kajiura: original 2026 study Florida Atlantic University: September 2026 research announcement

The team worked in shallow waters off southeastern Florida near the Jupiter, Palm Beach and Pompano Beach inlets. An underwater loudspeaker delivered controlled sounds; hydrophones measured pressure levels and helped model propagation. A drone filmed the sharks, with the boat’s known length providing a scale for measuring response distance. Ambiguous reactions and trials affected by other disturbances were excluded. Sullivan, Gerstein and Kajiura: original 2026 study

WHAT THE SHARKS RESPONDED TO

The experimental sounds were irregularly pulsed noise in three bands: 100–200 Hz, 200–400 Hz and 400–800 Hz. A 10,000 Hz control elicited no observed responses. The sharks’ average response distances were 40.7, 41.0 and 30.0 metres respectively. The greatest recorded distance, 74.0 metres, occurred in the lowest band. It is an observed maximum under this experiment’s conditions, not a hearing limit for the species. Sullivan, Gerstein and Kajiura: original 2026 study

THE SURPRISE IS DISTANCE, NOT A NEW FREQUENCY RANGE

Most recorded responses occurred beyond the study’s acoustic near-field boundary. The researchers defined that boundary using three wavelengths, so its location varied with frequency. The far field is a physical region of the sound field, not a single distance that applies to all sounds or a place where water particles stop moving. Sullivan, Gerstein and Kajiura: original 2026 study

Previous work had already shown shark responses to low-frequency sound. This study adds measured distances and directional behavior in free-swimming blacktips. Turning away from the speaker supports the inference that they obtained directional information. It does not show a shark mentally mapping a sound source with human-like precision, and it was not an experiment in locating prey. Sullivan, Gerstein and Kajiura: original 2026 study Chapuis and Collin: peer-reviewed hearing review

HOW AN ANIMAL WITHOUT VISIBLE EARS HEARS

Sharks have inner ears inside the head. Sensory hair cells convert mechanical movement into neural signals. In several inner-ear organs, relatively dense mineral particles lag behind movement of surrounding tissue, bending the hair-cell bundles. The ears also help with orientation and balance; semicircular canals detect rotational movement. Nieder and colleagues: three-species hearing comparison Sauer and colleagues: shark inner-ear variation

Underwater sound includes pressure fluctuations and particle motion. Unlike many bony fish, sharks lack a gas-filled swim bladder that can convert pressure fluctuations into motion for the ear. Evidence generally supports particle-motion detection. A specialized inner-ear region, the macula neglecta, may contribute to directional hearing, but its precise role remains unresolved. Chapuis and Collin: peer-reviewed hearing review Sauer and colleagues: shark inner-ear variation

The field experiment did not directly measure particle motion at every shark’s position or isolate a sensory organ. The authors propose mechanisms involving the inner ear, including possible specializations of the macula neglecta. Their behavioral evidence does not settle whether one proposed mechanism explains the response. Measuring pressure around the speaker is not equivalent to proving that sharks sense pressure directly. Sullivan, Gerstein and Kajiura: original 2026 study

HEARING, THE LATERAL LINE AND ELECTRORECEPTION

The lateral line is another mechanosensory system. Its receptors detect local water movements and flow patterns, helping an animal respond to nearby disturbances and wakes. It is distinct from the inner ear, even though both involve mechanical sensing. A distant acoustic response should not automatically be called lateral-line detection. Gardiner and colleagues: multisensory prey tracking

DIFFERENT SHARKS, DIFFERENT SENSORY WORLDS

A 2023 physiological comparison illustrates why one species cannot stand for all sharks. Researchers measured auditory evoked potentials in New Zealand carpet sharks, rig sharks and school sharks. Under their tank-test protocol, the upper detected frequency was 300 Hz for carpet sharks and 800 Hz for rig and school sharks. Those endpoints describe that method and those animals, not immutable species-wide limits. Nieder and colleagues: three-species hearing comparison

Anatomical research also documents differences in inner-ear structures across shark species. Such variation can generate hypotheses about habitat and hearing, but a larger sensory organ does not independently establish a particular detection distance. Blacktips are not great whites, and the new field results should not be transferred to the species depicted in this article’s hero. Sauer and colleagues: shark inner-ear variation

PREY, ORIENTATION AND WHAT SOUND MIGHT REVEAL

Sound can provide information about activity outside an animal’s immediate visual field. Earlier experiments found both attraction and avoidance, depending on the stimulus and its intensity. This explains why the new sharks swimming away does not contradict a possible role for sound in feeding. A sudden, intense artificial noise is not the same cue as a struggling prey animal. Sullivan, Gerstein and Kajiura: original 2026 study Chapuis and Collin: peer-reviewed hearing review

Orientation toward or away from sound can contribute to movement decisions, but this study did not demonstrate long-distance migration guided by acoustic landmarks. Nor does it show echolocation, sonar-like image formation or the detection of prey from miles away. For another example of a very different sensory and cognitive system, see our feature on the octopus mind. Gardiner and colleagues: multisensory prey tracking

WHY UNDERWATER NOISE MATTERS

If sharks detect sound over a wider area than a near-field-only assumption would suggest, noise assessments need to account for their acoustic environment. That is a conservation implication, not a measured population impact from this experiment. Shipping, construction and other activities differ in spectrum, duration and intensity; these artificial pulses cannot be used to assign one universal disturbance radius. Sullivan, Gerstein and Kajiura: original 2026 study Chapuis and Collin: peer-reviewed hearing review

A separate 2025 study exposed adult female Port Jackson sharks to ambient and human-generated sound recordings. During anthropogenic playback, shelter use increased and respiration changed. These results suggest effects that visible swimming behavior alone may miss, but they do not quantify injury or mortality in wild blacktip populations. Species, setting and outcome must remain distinct. Robins and colleagues: Port Jackson sharks and noise

The practical research priorities are broader species sampling, better particle-motion measurements and studies connecting exposure to feeding, habitat use and physiology. PRESDA’s analysis is that hearing deserves attention alongside other threats, while management decisions still require evidence of real-world exposure and consequences.

WHAT WE NOW KNOW, AND WHAT WE DO NOT

We have stronger quantified evidence that free-swimming blacktip sharks respond directionally to distant low-frequency sounds. We do not yet have a complete explanation of the mechanism, a new hearing range for every shark or proof that every detectable noise harms an animal. The discovery expands an experimentally documented sensory world while leaving important biological questions open. Sullivan, Gerstein and Kajiura: original 2026 study

The hero is an AI-generated editorial illustration of a great white shark. It is not a study photograph, and the research described here tested blacktip sharks.