Stripey Damselfish Use ‘Motion Dazzle’ As An Anti-Predator Strategy

How to hide from one’s enemies in plain view? Dazzle them with your brilliant stripes!

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Humbug damselfish (Dascyllus aruanus) on a reef in Lembeh, Indonesia. (Credit: Rickard Zerpe / CC BY 2.0)

I’ve written about why some reef-dwelling fishes, particularly clownfish or anemonefish, are striped and how the direction of their stripes — vertical or horizontal — predicts their aggressiveness (read more about that here). However, stripes on different species of reef-dwelling fish can serve other purposes.

For example, take the case of the whitetail dascyllus, Dascyllus aruanus. These small marine reef fish are often known by the peculiar common name, the humbug damselfish (Figure 1). These handsome shoaling fish have brilliant black and white vertical stripes. These stripes seem to act as camouflage that allows the fish to blend in with the corals in the background as long as they remain motionless. But humbug damselfish are very active during the day as they search for a meal. What is the purpose of these highly contrasting stripes if the fish are zooming around almost constantly?

Figure 1: Banded humbug damselfish in branching coral habitat. Banded humbug damselfish (Dascyllus aruanus) within branching corals. (Credit: iStock / doi:10.7717/peerj.18152)