Lending a Hand, or a Fin

By Sydney O’Brien, Wheaton College

Some people believe that helping someone in need is their duty, it is simply human nature to help others to obtain vital resources that they need to survive; almost anywhere you visit you will find food banks, soup kitchens, or people asking for donations. You might think this is a trait only found in humans, however a fish species off the coast of Australia believes they deserve a helping hand, and some of their neighbors agree! 

The coral trout off of Lizard Island in Australia spends his (or her) time searching for acquaintances to ask for a favor. Not every fish in the community will help him with what he needs so he must remember which individuals have helped him in the past, or risk rejection from asking someone new. Once he finds a reef octopus that he recognizes he approaches to get their attention and ask for their help in catching a small fish hidden in a crevice that he cannot reach. The fish uses “sign language” by pointing at the crevice to show the octopus where the fish is hidden. The octopus then removes the fish from the coral and one of them eats it. This behavior is beneficial to both species, they obtain more food working together than them hunting separately because they can both search to find more prey. 

This behavior is known as mutualism, a symbiotic relationship that benefits both participants. Many species choose to be mutualistic in situations where resources can be harder to obtain alone, such as in a coral reef where the larger fish cannot reach inside cracks and crevices, however the octopus can with its tentacles. Sometimes mutualism even exists across different species, which can be amazing to witness because they break a communication barrier and use signs to communicate. Fish, birds, insects, and humans all use mutualism in different ways to survive. By studying these interactions humans can gain insight into how the natural world works, and perhaps learn techniques for survival.