He who has the bigger mouth, wins!
Photo and caption by Ron Watkins
These two small pike blennies face off in a territorial battle or for the rights to a female. They hyper-extend their jaws as wide as they can to make themselves look bigger than they really are. I was able to watch them fight for almost a minute and eventually the bigger one in the foreground won out. It is usually difficult to get an image of a pike blenny completely out of the hole, so this behavior was a real treat to experience.
Location: Mexico in the Sea of Cortez, Madriff Islands