A signal for conspecifics
For striped marlin, color change involves the exposure of iridophores, resulting in a change from blue-grey to highly contrasting lateral stripes. While it is known that marlin can change color, this is the first time this has been linked to hunting or any social behaviour. “Colour change in predators is rare, but especially so in group-hunting predators. In this case, the colour change seems to act like a traffic light for conspecifics. Something like this: Stop, now it’s my turn to hunt,” said researcher Alicia Burns from the Humboldt University of Berlin, lead author of the study.
The discovery suggests that marlins have more complicated communication channels than previously suspected. “The colour changes may even serve a second purpose, namely to confuse the prey,” added IGB researcher Matthew Hansen, who led the study.
The team now wants to find out whether marlin also use their colour-changing abilities in other contexts; and whether they also change colour when hunting solo, and how these changes affect their prey. Following their discovery, the researchers have also observed similar colour changes in other predatory fish species: “We already have footage of hunting behaviour of sailfish and mahi mahi, where we have seen even more pronounced and variable colour change than in marlin,” said IGB researcher and SCIoI PI Jens Krause, one of the heads of the Cluster of Excellence and co-author of the study.