Scalloped Hammerhead and Bonnethead Sharks Have 360 Degree Vision
Posted on January 11th, 2010
The Netherlands – The old saying “to have eyes in the back of your head” holds somewhat true for scalloped hammerhead and bonnethead sharks (Sphyrna tiburo). A new study, published in the Journal of Experimental Biology, found these sharks possess a 360 degree field of vision. Virtually nothing can escape their view. The study also helps to explain why hammerhead sharks have such unusual shaped heads.
“Everyone wants to understand why they have this strange head shape,” says Michelle McComb from Florida Atlantic University, who worked on the study. “Perhaps their visual field has been enhanced by their weird head shape.”
With colleagues Stephen Kajiura and Timothy Tricas, she fished for juvenile scalloped hammerheads off Hawaii and looked for bonnethead sharks in the waters around Florida. The sharks were quickly transported back to the lab so McComb’s team could test the catch’s field of vision.
Like optometrists, the researchers swept light in front of each shark’s eyes. But as they did so, they recorded the eye’s electrical activity. When compared to other sharks with odd-shaped heads, the scalloped hammerhead turned out to have the highest measurements. Here’s the list of super see-ers, in order based on their visual skills:
#1. Scalloped hammerhead
#2. Bonnethead
#3. Blacknose (tied)
#3. Lemon shark (tied)
Other tests revealed the scalloped hammerheads and bonnetheads also possess stereo rear-view vision and incredible depth perception. Part of this is due to their head shapes.
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You can watch a video with hammerheads here.
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