Cameras fitted to tiger sharks are giving scientists an unprecedented* look into the life and death struggles of the predators and their prey.
Small video cameras have been attached to the fins of tiger sharks at Ningaloo Reef in Western Australia.
And for the first time, this footage has been combined with knowledge about the structure of the eyes of tiger sharks to develop a “virtual* visual system” that provides a view of life under water as the sharks see it.
It has also provided new understanding into the behaviour of sea turtles and how they avoid becoming a meal for a tiger shark.
“When watching the raw* camera footage of tiger sharks approaching sea turtles it seemed strange that often tiger sharks swam directly over a turtle sitting on the reef, a potentially easy meal,” said lead study author Dr Laura Ryan, from the School of Natural Sciences at Macquarie University.
“However, when we look at the visual cues* through the visual system of the tiger shark it is in fact extremely difficult to detect the turtle and, particularly when they remain motionless, blending into the background can allow them to camouflage* themselves from attack.”
This shark’s-eye view has provided some surprise insights* into the behaviour of tiger sharks, including how they hunt.
Dr Ryan said a tiger shark’s eyesight was much less clear and sharp than a human’s vision and the vision of the video cameras, which meant they had to rely on the sea turtles moving in order to see them.
“For sea turtles, their best form of defence from attack may be to simply remain still in the presence of the predator,” Dr Ryan said.
Tiger shark cam
The video tags fitted to the sharks also contained sensors to track even their smallest movements, allowing swimming behaviour and the shark’s reaction to turtles to be monitored.
The study by scientists from Macquarie University, the Australian Institute of Marine Science, University of Western Australia, Murdoch University, Stanford University and Oregon State University, is the first to look at camera footage through the visual capabilities of the animal they are mounted on.
The research, published in Royal Society Interface, found that although the sharks’ eyesight was poor, their vision was still important.
The researchers noticed the sharks’ behaviour changed when they saw a sea turtle. The sharks slowed down and performed lots of turns, suggesting they had entered a search mode for their prey.
“The picture that emerges through the eyes of the shark is one of almost slow-motion pursuit of a slow-moving prey, rather than a high-velocity* ambush* that we tend to think of when we see other big predators in action, such as white sharks,” said study co-author Dr Samantha Andrzejaczek, from the Hopkins Marine Station at Stanford University.
She said the sharks’ slow-motion hunt was probably the result of a lack of food in the environments they lived in, meaning they had to be careful not to use too much energy chasing prey.
The team now hopes to use its approach to study how other species see their world.
- unprecedented: never done or experienced before
- virtual: created by computer technology and appearing to exist but not existing in reality
- insights: clear and deep understandings
- raw: unchanged, not edited
- cues: signals or hints to begin doing something
- camouflage: hide by blending in with the surrounds
- high-velocity: operating at high speed, with great force
- ambush: sudden and surprising attack
- What type of sharks were the cameras fitted to?
- What did the scientists combine the footage with to come up with the “virtual visual system”?
- What did the footage reveal about the behaviour of sea turtles?
- How did the sharks’ behaviour change when they saw a sea turtle?
- Why do the scientists believe these sharks conducted “slow-motion” hunts?
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1. Tiger shark fact file
Make a list of top five interesting facts you learnt about tiger sharks from this news article.
Identify one more thing you would like to know about them and then do some research to find out.
Time: allow 25 minutes to complete this activity
Curriculum Links: English; Science
The final sentence of the news article tells us that the team now hopes to use its approach to study how other species see their world. If you were part of the team, which animal would you want to study next and why?
Time: allow 10 minutes to complete this activity
Curriculum Links: English; Science
New VR experience
Imagine if the footage of the tiger shark was sold to Google Expeditions so it could be turned into a virtual experience. You could put on a VR headset and play the video to see through the eyes of a shark. Wouldn’t that be amazing?
What other animals would you like to experience?
Make a pitch to Google about which animal you would love to have a non-invasive 360-degree camera attached to, so that they could create a unique wildlife experience for us.
Try and include any educational benefits you can think of to really enhance the value.
Share your pitch with a classmate to see what they think.