The Cookiecutter shark (Isistius brasiliensis). NOAA/Public Domain The cat-sized shark in the picture to the right doesn't look that intimidating, but it has the power to take down an entire nuclear submarine. The fish's strange bite can get at the softer areas of the submarines, National Geographic's Ed Yong reports:

The fearless cookie-cutters have even disabled the most dangerous ocean creature of all—the nuclear submarine. They attacked exposed soft areas including electrical cables and rubber sonar domes. In several cases, the attacks effectively blinded the subs, forcing them back to base for repairs. They later returned, fitted with fibreglass coverings.

The attacks happened in the 1970s and the problem seems to have been taken care of, though in several cases the sharks did enough damage to the vessel's sonar equpiment that the oils inside that transmit sound would leak out of the ship and break the equipment — the subs could no longer see what was around them, according to the ReefQuest Centre for Shark Research.

Nuclear subs obviously aren't all that tasty, but they seem to bite just about anything — even research equipment in the ocean. The distinctive bites have been found in all kinds of fish and other sharks, and even a human has been attacked by the little guys.

See the rest of Yong's blog post for more fascinating facts about the cookiecutter shark and the analysis of a new paper out in Pacific Science this month, detailing cookiecutter bites on a great white shark. Here are some more images:

Pomfret with damage from a cookiecutter shark (Isistius brasiliensis) NOAA/Public Domain