A new species of mosquito fish has been discovered. What is so unusual and strange about the discovery is that the fish has hook like barbs on the males penis. The first thing I thought of when I read that was why does it matter, female fish lay eggs and the male fish follows with spreading its sperm over the newly laid eggs, no sexual intercourse like animals is performed. That was until I found out that the mosquito fish are live bearers, so they do have intercourse. You can read more about the new fish here.
If you are not aware, there are many species of animals that have barbs on their penis', males cats are one. Their purpose is to cause the female cat to ovulate after intercourse, since female cats do not ovulate until they are bred and not when they come into heat like most other mammals.