Sydney, Aug 2 (IANS): Researchers have found hammerhead sharks to be just like lazy human swimmers by choosing to swim on their side in a bid to conserve energy, a study published in the journal Nature Communications showed.

An international team of scientists observing endangered great hammerhead sharks in Australia, Belize and Bahamas originally thought one of the predators was sick, but on closer observation they found it would switch from one side to the other, Xinhua news agency reported.

Further observations using underwater cameras and accelerometers led them to discover the predators spend up to 90 percent of their time swimming rolled at angles between 50 and 70 degrees using their large dorsal fin to generate lift.

Hydrodynamic modelling with a physical model of a great hammerhead shark found the animal would suffer the least amount of drag, and therefore expend the least amount of energy, at precisely that angle range.

"The animals reduce the cost of transport by about 10 percent by using the side-swimming method" compared with traditional upright swimming, the study's co-author, James Cook University researcher Adam Barnett said in a statement on Tuesday.

"It just goes to show how much we don't know about what goes on in the ocean."

Great hammerhead sharks are solitary predators; however, due to overfishing and other human-related factors, they are disappearing from oceans at an alarming rate.