THE OCEAN IS A GAMETE SOUP

Those of you who love to swim in the ocean and consider it your happy space should quit reading now.  I’m only going to ruin it for you (perhaps).  Many aquatic organisms release their gametes (eggs and sperm) into the ocean waters and hope they meet up and form babies.  This makes the ocean a bit like a gamete soup.  All those sperm and eggs floating around in the ocean currents…so this begs a question.  How does an egg make sure only the sperm of the correct species fertilizes it?  Barriers!  Most of these eggs have a barrier that chemically recognizes the correct species sperm and allows it in.  Once a sperm has entered, the egg forms a chemical barrier that prevents other sperm from entering.  It is a chemical lock and key system!