With a reputation as one of the ocean's more ruthless carnivores, you'd think a tiger shark would have little hesitation in taking on live prey. But a new study has revealed that when presented with a ready-to-eat-meal even these predators can't resist the easy option, with the animals preferring to chow down on dead sea turtles rather than tracking and killing their healthy brothers and sisters.
The waters around Raine Island, off the northern coast of Australia's Great Barrier Reef, play host to as many as 12,000 green sea turtles each time nesting season rolls around. These animals flock to lay eggs on the beach, but after long nesting periods they can become exhausted and weakened, with many then dying throughout the night and washing into the ocean.
All this sea turtle activity and feeding opportunity draws hungry tiger sharks to the area. By using satellite tagging to monitor the behavior of these sharks, researchers from the University of Miami discovered something a little surprising about their feeding habits. The data captured over the five-year study revealed that the tiger sharks were swimming right past large amounts of live prey in search of something that puts up less of a fight.
"The sharks are probably having to go out of their way to avoid hundreds of live turtles to find the dead and weakened ones," explains the study's lead author Neil Hammerschlag. "It is energetically more advantageous and also safer for sharks to scavenge on carcasses rather than have to chase down live turtles. In this way, tiger sharks are similar to terrestrial carnivores, such as hyenas and polar bears, which will selectively scavenge when the opportunity arises."
Interestingly, this behavior seems to remove a lot of tension in the water, with the data also revealing that the turtles swim freely amongst the scavenging sharks and don't perceive them as a threat.
The team's research was published in the journal Behavioral Ecology and Sociobiology and you can hear from Hammerschlag in the video below.
Source: University of Miami