South Korea sees your 'dog eat dog' idiom and raises you 'shark eat shark'.

This female sand tiger shark, which can grow up to more than 10ft long, decided that the food it was being provided in the aquarium wasn't good enough and chowed down on a 4ft male banded houndshark and proceeded to digest it over the next 21 hours until only the tail was left visible. Not the most subtle way of asserting your authority but definitely clear.

Via Twitter