Clever fish 'use tools to open shells'

Yellowhead wrasse was one of the the fishes seen using tools to get food

A new study has found fish using tools to open shellfish.

Tool use is when creatures use an item to achieve to a goal, like getting food or water, communicating, grooming or as a form defence.

Many years ago people thought tools were something only humans used, but since then there have been studies on other mammals and birds that use tools too.

Now scientists have shown that it's not just mammals and birds, but also fish that have this clever skill.

Wrasses are type of colourful fish that live near coral reefs

Dr Juliette Tariel-Adam from the School of Natural Sciences at Macquarie University in Australia led a project tracking tool use in multiple species of wrasses, a type of colourful reef fish.

The study, which is published in the journal Coral Reefs, showed that several species of fish used hard surfaces, like rocks, to crack open shellfish like crabs or molluscs so they could eat them.

The researchers found the first examples of this sort of tool use from several species of wrasses, suggesting the behaviour is much more common than previously thought.

"Tool use is typically associated with humans, but this behaviour is proof that fish are far cleverer than they get credit for," said Dr Juliette.

Part of the project used citizen science to gather video and photo evidence.

Divers, snorkelers, and marine enthusiasts were encouraged to report what they saw.

This shows a screenshot from a video of a yellowhead striking a brittle star (similar to a starfish) arm on a hard surface to break it open

The study found that wrasses are flexible in their tool use, selecting different types of hard surfaces to crack open different types of prey.

"For a long time, tool use was thought to be exclusive to primates and birds," said Professor Culum Brown, head the Fish Lab at Macquarie University and senior author of the study.

"Our findings add to a growing body of research showing that fish are just as intelligent."