Humans think of bondage as kinky. For some animals however bondage has become a biological necessity. Today I bring you a couple of examples of bondage in the animal kingdom. Life for a blood fluke is a real gamble. First it has to find a host, in fact three hosts. Firstly its eggs hatch and the fluke larva infests a water snail. Then it takes up residence in a fish. Then a human eats the fish and it infests his or her blood stream. So with all this moving about how does it find time f...