Studies have found that spotted pipefish stealthily hunt by camouflaging themselves behind other fish, such as parrotfish, to trick their prey, a novel survival strategy that is likely to become more common due to the degradation of coral reefs.
An experiment conducted on a coral reef demonstrated for the first time that predators use the movement camouflage of other animals to approach their prey without being detected.
A new study is the first to provide experimental evidence that the spotted pipefish (Aulostomus maculatus) can hide itself by swimming closely behind another fish while hunting, reducing the likelihood of being spotted by prey.
In this "shadow" behavior, the long, thin spotted mouth fish uses non-threatening fish such as green parrot snapper as a camouflage to get close to its dinner.
This is the only known example of a non-human animal utilizing another animal as a covert form. The study consisted of several hours of diving in the Caribbean, pulling hand-painted model fish along power lines.
The elongated spotted mouth fish uses larger, non-threatening fish such as the green parrot snapper as a camouflage in order to get close to its dinner without being detected. Image Credit: Sam Marchette
Dr Sam Marchett, a researcher in the Department of Zoology at the University of Cambridge and lead author of the study, said: "When a spotted nozzle fish swims against another fish, it is either completely hidden by its prey or seen by its prey but cannot be identified as a predator because of its different shape. "
Deep-split orbital damselfish (Stegastes partitus) forms colonies on the seafloor and is a common food for spotted pipefish. In a coral reef near Curaçao in the Dutch Caribbean, researchers set up an underwater system to pull a 3D-printed model of a spotted pipemouth fish with nylon thread through a colony of damselfish and film their reactions.
The deep-split orbital saw damselfish will quickly flee from this predator to avoid being eaten. Source: Sam Marchett
When the spotted muzzle fish model swam by alone, the deep-split orbital saw damselfish swam over to observe and quickly flee back to shelter to deal with the threat of predation.
When a model of the herbivorous green parrot (Sparisoma viride) swam by alone, the deep-split orbital saw damselfish had far fewer viewing movements and reactions.
When the spotted muzzle fish model is attached to the side of the green parrot model – to replicate the shadow behavior of a real spotted muzzle fish – the deep-split orbital sawfish reacts in the same way they react to a separate green parrot model: they find no threat.
"I was amazed at how different fish react to different fish species, and it's great to be able to observe this in real time," Marchet said. "
The study, which was carried out by collaborators from the University of Bristol, was published in the journal Current Biology.
When the two passed together, the deep-split orbital saw damselfish did not find a threat. Image courtesy of Sam Matchette
Professor Andy Radford of the University of Bristol's School of Biological Sciences is a co-author of the study.
Marchet and his co-author, dive buddy Christian Drerup, spent hours underwater, experimenting almost motionless.
Their earlier survey of divers working at dive shops in the Caribbean Sea revealed that spotted pipemouth fish often swim with green parrot and other reef fish, but the reason for this extraordinary behavior has not been verified.
In addition, divers are more likely to see this shadow behavior on degraded, less structurally complex reefs.
The researchers spent hours underwater pulling model fish along a tightrope past schools of fish and filming their reactions. Image courtesy of Sam Matchette
Coral reefs around the world are being degraded due to a warming climate, pollution, and overfishing. Strategies for hiding behind other moving fish may help animals adapt to the effects of environmental changes, the researchers say.
"The shadow behavior of the spotted nozzle appears to be a useful strategy to increase the success rate of hunting. Dr James Herbert-Read, senior author of the study and a professor of zoology at the University of Cambridge, said: "As there are fewer structures on coral reefs for them to hide, we may see this behaviour becoming more common in the future." "
编译自/scitechdaily