"Unlike short-haul terrestrial fiber cables or old copper cables where the fiber did not emit noticeable fields, undersea cables must carry high voltage power to the undersea repeaters, which result in both electric and magnetic fields around and along the cable ... Some sharks mistaken the electric fields for distressed fish and attempt to feed on the cable," a report studying the phenomenon has noted.
"Just a little bite is enough to get through the jacket and damage the fibres," Chris Lowe, a professor who runs shark lab at California State University, Long Beach, was quoted as saying.
Google, however, ensures its cable is sheathed in a Kevlar-like protective coating to keep the sharks from chomping through the line, Network World reported, quoting Google product manager Dan Belcher from a Google marketing event in Boston last week.
Since fiber is made of fragile glass, its casing is built to protect it from breaking. A fiber-optic cable often includes (listed from the outer layer inward): An outer polyurethane jacket, a protective layer (made from a material like kevlar), a plastic coating (in different colors, so technicians can follow the path of each strand), and enclosed in all of these, a glass fiber.
At the event, Belcher also played a video of a shark attempting to eat some undersea fiber optic cables.