This terrifying mouth belongs to the cookiecutter shark, which gets its name from the circular-shaped chunks of flesh it removes from its victims. A horrifying visual, yes, but these sharks are actually parasites, which means they harm — but do not kill — other fish or marine mammals.
As far as sharks go, these are on the smaller side, measuring up to 19 inches. They prefer warm water and live in oceans near the equator at depths of 1,000 feet.
Previously, cookiecutter sharks were called cigar sharks for two reasons: First, their bodies are long and cylindrical like a cigar, and second, they have a dark collar around their gills that looks like the band on a cigar.