Anglerfish have the most extreme difference between sexes in the Animal Kingdom. The condition is scientifically known as sexual dimorphism. It’s where the two sexes of the same species exhibit different characteristics beyond the differences in their sexual organs.

Even more bizarre than their extreme physical differences is the way they mate which is explained in the BBC video above. If you haven’t already, be sure to check out the Oatmeal’s legendary comic strip: How the Male Angler Fish Gets Completely Screwed