The mystery of the Hammerhead sharks

14 marzo 2007

Hammerhead sharks form really large schools of over 500 specimens. This habit is not at all common shark behaviour, and shark experts still do not know the reason. And what makes it even more interesting is the fact that they school in large groups around underwater mountains.

Peter Klimley, from the University of California, has been studying hammerheads and their behaviour for more than 20 years. He is looking closely at this curious tendency of hammerheads, and thinks that the behaviour is related to the magnetic polarity of seamounts.

According to National Geographic, Klimley speculates that hammerheads follow magnetic patterns, using them almost like roads to guide their travel.

According to this, when it comes time for the sharks to continue their migration, the animals may follow magnetic "highways" across the ocean floor—swimming from landmark to landmark using the seamounts as "stepping stones."

Another classic mystery about these sharks is their bizarrely shaped head. Some experts think that the wide lobes of the hammerheads allow them to have longer electro-receptors. In fact, Klimley thinks that these electro-receptors allow them to detect the magnetic fields.

Other interesting fact is that hammerheads schools only exist during daytime. In the evening, each hammerhead shark leaves the school and spends the night alone. One clue to this behaviour might be found in the fact that really big hammerhead sharks hardly ever take part in these schools. Schooling might therefore be a way for small and medium sized hammerhead sharks to avoid being preyed upon by large predators.

More info and sources: 1, 2, 3, 4, 5