Animals use all manner of techniques to camouflage and conceal themselves from predators and prey. One species of fish does something particularly clever. Trumpetfish hide behind bigger, harmless fish to avoid detection by prey.
They are the first non-human predator we know of that hides behind other animals to sneak up on prey. What makes the trumpetfish even more impressive is their choice of concealment: the stoplight parrotfish. These parrotfish do not feed on other fish, so do not spook the prey species.
Known to divers
Divers have observed this unusual behavior and it is even mentioned in guidebooks, but until recently, it was never studied. But it reminded zoologist Samuel Machete of how humans creep up on waterfowl by hiding behind cattle and horses. Machette’s team used 3D models of both parrotfish and trumpetfish to determine whether the shadowing behavior helped the trumpetfish hunt in a similar way.
Researchers placed a pulley system of the trumpetfish and parrotfish models into the ocean. They pulled it past colonies of damselfish, a common prey species. When the trumpetfish were pulled by themselves, the damselfish fled. When it was just the parrotfish, the damselfish did not react to its presence.
They then tried attaching the smaller trumpetfish on the blind side of the parrotfish. The damselfish only fled when the models were much closer to the model.
“[This] shadowing behavior likely reduces detection of trumpetfish by their prey and allows trumpetfish to approach closer,” the team wrote in the new study.
It is the first study that attempts to measure the advantage such concealment gives the fish. Trumpetfish also have methods to hide from prey. They can change color to blend into their background, lurk behind vegetation, and attack from above.
The models used by the research team. Photo: Sam Matchette
No one has observed this technique in other predators, though it is very possible that some use it. As climate change continues to impact coral reefs, it is likely this behavior will become more common. Dead coral can’t conceal predators, which will need to use other methods to hide themselves.
“We might see this behavior becoming more common in the future,” said co-author James Herbert-Read.
