A large olive ridley turtle rests peacefully on the sea bed as it is manicured by an eager group of reef fish. Turtle shells are often populated by epibionts, or tiny ocean hitchhikers, who use the shell as a home and a way of spreading their gene pool to new areas. They do not harm the turtle in small numbers, but should their presence grow too great, the turtle will be uncomfortably encumbered. To prevent this from happening, turtles have been known to recruit the services of fish, who feed on these epibionts in a mutually beneficial, symbiotic relationship. Even so, this behaviour is rarely witnessed by divers, and I was delighted to find this scene upon dropping in for a dive at Cabo Pulmo National Park, where strict marine protection measures have resulted in a safe haven for marine life.