Tiger sharks stalk the world’s tropical and temperate waters, where they have the second-highest rate of attacks on humans on record. Together with the great white and bull shark, tiger sharks are part of the formidable “Big Three”. Since the year 1580, at least 34 people have been killed by tiger sharks and another 95 have escaped with their lives.
The International Shark Attack File of Florida Museum said: “Tiger sharks are often curious and unaggressive when encountered yet are one of the three species most commonly implicated in shark attacks and fatalities and should be treated with extreme caution and great deal of respect.”
Therefore, researchers at The University of Western Australia, Australian Institute of Marine Science and Murdoch University may have been surprised to discover tiger sharks tend to live life in the slow lane.
A study published today (August 19) in Royal Society Open Science, has challenged the widely held belief tiger sharks are swift and deadly predators stalking their prey.
Instead, the sharks appear to yo-yo through the water at a leisurely pace.
Shark news: Tiger sharks have the second highest rate of attacks on humans
Shark news: Tiger sharks appear to live life in the slow lane
Led by Dr Samantha Andrzejaczek from the University of Western Australia’s Oceans Institute, researchers deployed 21 camera tags on sharks in the Ningaloo Reef, Western Australia.
The sharks were tracked for a period of 24 to 48 hours, recording data 20 times every second.
The instruments tracked the sharks’ tailbeat movements in the same way a fitness tracker records footsteps during a run.
The researchers used this data to calculate how much energy the sharks on the reef spent in search of prey.
Surprisingly, the sharks took their time, moving from the surface to the bottom.
They were conserving energy by moving up and down
Professor Charitha Pattiaratchi of the Oceans Graduate School said: “These tigers actually had accelerometers, they had video, so you could actually see the behaviour of the tiger sharks as they moved around migrating, looking for food, etc.
“So we wanted to find out a little bit more about how do they move.
“What was very common was that the sharks didn’t swim at a very particular depth.
“They were always moving up and down, so they were conserving energy by moving up and down the water column.”
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Shark news: Tiger sharks are among the three deadliest species
Shark news: The sharks conserve energy when on the prowl for food
Dr Andrzejaczek added: “We could see the environment they swam through, and more importantly, begin to understand why they are swimming the way they do, and why they may be choosing particular habitats.”
According to Dr Mark Meekan, from the Australian Institute of Marine Science, the up-and-down movement helps the sharks reduce energy, compared to swimming at the same depth.
Event larger predators like the tiger shark have no guarantee of catching a meal.
It is, therefore, critical they save energies while on the hunt.
Tiger sharks are among the largest species of shark, growing up to 18ft (5.5m) long.
They typically feed on most marine animals, sea birds and even some land animals.
Tiger sharks also have a reputation for eating human rubbish.
Unfortunately, the sharks are considered a near-threatened species and are being targetted for their fins, flesh and oil.
Florida Museum said: “Shark fishery catches of tiger sharks are documented from the western Atlantic, Australia, India, Papua New Guinea, Brazil, and Taiwan.
“In the United States, tiger sharks are the third most common of the large, coastal sharks caught.”