Disruptive colouration in reef fish

Yay – new research published today in the Journal of Experimental Biology from my PhD work with members of the Sensory Neurobiology Group at QBI and the Ecology of Vision Group at the University of Bristol.

Our work looked into the barred body patterns of a little fish called a three-barred humbug (Dascyllus aruanus). We aimed to see how these fish appeared to predators – by literally asking two different fish – the coral trout (Plectropomus leopardus) and the slingjaw wrasse (Epibulus insidiator) whether they could find the humbug against different backgrounds.

Trout + humbugs. Dream photo?

We predicted that when the background was very similar to the humbug, the predators would have a hard time finding the prey.

We designed a range of backgrounds that either matched the humbugs’ patterns, or were slightly different in terms of the bar frequency (how many bars were within the background). We also tested whether the width of coral branches affected how easily the humbugs were found by the two predators – this would help us understand whether particular corals might be better for the humbugs to live in.

I stalk these guys for a living. I love them.

The predators did the experiments well which was a relief! They showed us that although matching the background made it harder for them to find the humbugs, it was hardest when the background was slightly more complex (more bars or thin coral branches) than the humbug’s body pattern.

So, to conclude:

  1. Match your background to reduce predator detection.
    To get to next level crypsis, slightly mis-match your background – this will hopefully increase the disruptive elements of your body pattern and make it much harder for the predator to identify you as a tasty prey item.

There’s a link to the PDF here. If you’re stuck behind a paywall, contact me for a copy.

Also, be sure to check out fellow visual ecologist, Dr. David Wilby’s paper which landed the cover image!

Big fishy love,