Shark Sensors Show Underwater Behavior [Video]


While tracking a shark is common for scientists, attaching video cameras, accelerometers, magnetometers, and other sensors to the sharks is new.  The cameras and sensors allowed researchers to not only see through video where the sharks were swimming, but also to precisely track their behavior.  What scientists discovered was that the sensors on the sharks showed some rather unexpected underwater behavior.

The instruments were attached to reef sharks living in Hawaii and were used to record exact details of the animal’s position in the water and movements such as acceleration.  The sensors also provided information on the ambient water temperature and magnetic field.  Until now, sharks were tracked with only satellite tags.  The satellite tags provided details on the whereabouts of the animals but did not provide comprehensive data as to what they were doing.

Surprisingly, it was discovered that several different species of shark schooled together.  There was a mixture of sandbar sharks, hammerheads, and oceanic blacktips.  Carl Meyer, a researcher at the University of Hawaii, believes that the sharks were banding together to fend off any possible attacks from tiger sharks.  A tiger shark can grow over 12 feet long and are the largest common coastal sharks in Hawaii.  They regularly consume other sharks.  Because the hammerheads, blacktips, and sandbar sharks are considerably smaller, they may be swimming together in an effort to keep from being eaten.

The sensors on the sharks did not just show unexpected behavior.  The instruments are used to determine how much energy the animals use while swimming as well as exactly how they swim.  Some of the technology attached to the sharks is sensitive enough for researchers to construct three-dimensional models.  This will greatly enhance the knowledge base that has already been gathered.

The end result of the studies will be a much deeper understanding of the ecological function of these sharks.  Determining the role of each creature in the ocean can only increase comprehension of how each species affects the health of the entire ecosystem.  More projects are underway to round out the data being gained with the current sensor array.  Future instruments may be manufactured specifically to be ingested by sharks and other animals.

The future sensors, after being ingested, will provide insight into various feeding habits.  The instruments will likely track digestion rates as well as record what the animals are eating.  By using electrical measurements, the sensors will also provide information on when feeding occurs as well as how much is being consumed.

For now, studies continue on the reef sharks.  The cameras and sensors already deployed are being retrieved and the data will be analyzed.  Additional instrument packages will be attached to other shallow water sharks to further the information which is already being gathered.  More sensors are being put on deep-sea sharks like the bluntnose sixgill shark to show their underwater behavior.  The past several decades have allowed scientists to track where the sharks roam.  Now they will be able to have a better understanding about why they go where they go as well as what they actually do when they get there.

By Dee Mueller

National Geographic
Wildlife Extra
e! Science News

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