Watch Your Back: Sharks Can Detect Human Field of Vision, Will Approach from Behind

New research from the Shark Research Institute and the University of West Florida reports that sharks are able to comprehend body orientation and use that information to their advantage when on the hunt.

The research, published in the journal Animal Cognition, suggests that sharks' ability to detect body orientation enables them to initiate attacks on prey from a blind side, which is an effective hunting technique.

Research leaders Erich Ritter of the Shark Research Institute and Raid Amin of the University of West Florida say the takeaway from their research is simple: Don't turn your back on a shark.

The researchers used human subjects for their tests, observing the pattern of approach the sharks took as they neared the subjects. Caribbean reef sharks, the species used in the tests, were chosen because it is a type of shark frequently encountered by divers in the Bahamas, though it is not considered to be a dangerous species regarding incidents with humans.

Ritter and Amin designed a test to evaluate whether sharks show a measurable preference based on body orientation when approaching a person and if they choose a certain swimming pattern when close to a human being. In one test, they instructed a scuba diver to kneel on the seafloor looking forward with his back exposed. In another two divers were asked to kneel back-to-back to eliminate a blind area.

When compared to the back-to-back divers, the single, back-exposed diver was approached from behind by the sharks at significantly higher rates, which Ritter and Amin took as evidence that sharks can identify human body orientation.

While the researchers suggest sharks are capable of identifying body orientation, the factors affecting the distance of the approach remain unclear.

"Our discovery that a shark can differentiate between the field of vision and non-field of vision of a human being, or comprehend human body orientation, raises intriguing questions not only about shark behavior, but also about the mental capacity of sharks," Ritter said in a press statement.

"The more research is conducted on how sharks sense and interpret humans, the better we will understand how to cope with them in their habitat," Amin added.