Hygienic sharks visit cleaner fish
Sat, 19 Mar 2011 18:26:45 GMT
A recent study suggests that thresher sharks are very hygienic and repeatedly visit undersea mountains to get rid of their parasites and dead skin.
Scientists, who filmed over 1,000 hours of footage of the sharks at a seamount off the northern tip of Cebu in the Philippines, observed that the predators swam slowly around tropical seamounts so that cleaner fish could nibble off their parasites.
"They visit the site very regularly," lead researcher Simon Oliver of UK's Bangor University told the state-funded BBC. "A huge dive tourism site has evolved around them."
"They pose, lowering their tails to make themselves more attractive to the cleaners," he explained.
"And they systematically circle for about 45 minutes at speeds lower than one meter per second." This is about half the speed at which the sharks usually swim.
According to the study published in the journal PLoS One, this is the first time that such behavior has been seen in the species and researchers believe it to show the significance of cleaner fish for sharks.
Oliver, who has been studying thresher sharks for more than five years and founded the Thresher Shark Research and Conservation Project, says the undersea mountains, where the cleaner fish live, are vital for the sharks' health.
"It's like us going to our local GP if we had a head full of lice," said Oliver. "If we weren't able to get them treated, they could cause infections and other complications.
"Our findings underscore the importance of protecting areas like seamounts which play an important part in [the sharks'] life strategy to maintain health and hygiene."
Oliver also noted that the site of his research had been badly damaged by dynamite fishing.
"The work uniquely describes why some oceanic sharks come into coastal waters to perform an important life function which is easily disturbed by man," said Bangor University marine biologist, Dr. John Turner, who also took part in the research.