Watch these predatory fish use fast color ch

Striped marlin are some of the fastest animals on the planet and one of the top predators in the ocean. When hunting in groups, individual marlin will take turns attacking schools of prey fish one at a time. Now a new study is reported in the journal Current Biology on February 5 helps explain how they can coordinate this turn-taking style of attacking their prey to avoid hurting each other. The key, according to the new work, is rapid color change.

“We have documented for the first time rapid color change in a group-hunting predator, the striped marlin, as groups of marlin hunt schools of sardines,” said Alicia Burns of Humboldt University in Berlin, Germany. “We found that the attacking marlin ‘lighted up’ and became brighter than its peers during its attack before quickly returning to its ‘dim’ color after its attack.”

Burns and his colleagues, including Jens Krause, explained that using drones in their research gave them new insight into how marlins move and hunt. As they analyzed the video footage they captured via drone, they noticed something unexpected: the stripes on individual marlins visibly brightened as a fish moved in for an attack. As they swam, those lines faded again. Do fish change color to communicate with each other?

To explore this question in the new study, researchers analyzed 12 high-resolution video clips, each containing two separate attacks on a school of sardines by two different marlin. They also determined the contrast of stripes on two attacking marlin compared to a randomly selected non-attacking marlin. Their analysis confirms that predatory fish change color rapidly, suggesting that color change can serve as a reliable signal of an individual’s motivation to come in for an attack.

“Color change in predators is rare, but especially in group hunting predators,” Burns said. “Although it is known that marlin can change color, this is the first time it has been linked to hunting or any social behavior.”

The discovery indicates that marlins have more complex communication channels than previously thought. The researchers suggest that the color changes may serve the dual purpose of confusing their prey.

They now hope to explore this idea, among other questions. For example, they want to know if marlins use their color-changing abilities in other contexts. They want to know if they still change color when hunting alone and how the changes affect their prey. They also observe similar color changes in other predatory fish species.

“We now have footage of the hunting behavior of sailfish and mahi mahi where we see clearer and more color changes than marlin,” Burns said.

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Current Biology, Burns et al. “Rapid color change in a group-hunting pelagic predator when attacking schooling prey” https://www.cell.com/current-biology/fulltext/S0960-9822(23)01740-2

Current Biology (@CurrentBiology), published by Cell Press, is a bimonthly journal featuring papers in all areas of biology. Current Biology strives to stimulate communication in various fields of biology, both by publishing important findings of general interest and through highly accessible front matter for non-specialists. Visit http://www.cell.com/current-biology. To receive Cell Press media alerts, contact [email protected].