Grey reef shark
Grey reef shark. Photo courtesy of Flickr Creative Commons/PacificKlaus

PERTH (AUSTRALIA)- The diving behaviour of sharks could be influenced by the moon, water temperature and time of day, new research by the University of Western Australia’s Oceans Institute and the Australian Institute of Marine Science has revealed.

Grey reef sharks
Scientists of the two institutes studied about 40 grey reef sharks – commonly found on coral reefs in northern Australia and in the Indo-Pacific – and found they stayed in deep water during a full moon and moved to shallow water with the new moon.

Diving behavior
The sharks were tagged near Palau, east of the Philippines, and followed for two years using acoustic telemetry. The group of mostly adult females were recorded diving to an average depth of 35m in winter and 60m in spring.

Deeper water
In winter, when deeper waters were colder, the sharks remained closer to the surface where the water was warmer, but moved around to a range of depths in summer.

Researchers suggest that because sharks are cold blooded, they may prefer warmer water to conserve their energy.

To their knowledge, the researchers say, it  is the first time such patterns have been observed in detail for reef sharks.

Source: The Australian News