Some additional examples: http://www.businessinsider.com/scariest-parasites-in-the-world-2012-6?op=1 http://www.businessinsider.com/scariest-parasites-in-the-wo

Some additional examples: http://www.businessinsider.com/scariest-parasites-in-the-world-2012-6?op=1 http://www.businessinsider.com/scariest-parasites-in-the-wor... The Sacculina genus of parasitic barnacles--which has dozens of species--is spectacularly creepy: http://en.wikipedia.org/wiki/Sacculina http://en.wikipedia.org/wiki/Sacculina They infect both female and male crabs and completely subvert their biochemistry, to the extent of feminizing the males. They then lay their own eggs in the crab's carapace, the way the crab normally would, and the crab--male or female--behaves as if it was carrying its own eggs.