Small fish hides behind other bigger fish to sneak up on its prey

A species of tropical fish swims behind different fish to cover itself whereas attempting to find prey. Better understanding these behaviours may assist scientists predict how some animals might adapt to the potential degradation of coral reefs.

Over the previous few a long time, divers within the Caribbean have noticed West Atlantic trumpetfish (Aulostomus maculatus) – a small coral reef-dwelling predator – swimming alongside bigger, non-predatory fish, resembling stoplight parrotfish (Sparisoma viride), which they don’t prey on.

Swimming near parrotfish might enable trumpetfish to get nearer to their prey with out spooking them, says Sam Matchette on the University of Cambridge. To check this concept, Matchette and his colleagues needed to know whether or not one of many trumpetfish’s most typical targets, a species of damselfish (Stegastes partitus), are actually duped by this method.

In coral reefs off the Caribbean island of Curaçao, the researchers arrange tripods linked by a nylon line in order that 3D fashions of dummy fish could possibly be pulled previous colonies of actual damselfish.

First, they pulled a mannequin of a trumpetfish over damselfish, discovering that the latter shortly fled. They then dragged a mannequin of a parrotfish over damselfish, discovering that they continued their exercise as regular. But when each trumpetfish and parrotfish have been pulled over collectively, mimicking how trumpetfish swim carefully to parrotfish, the damselfish fled, suggesting that they’re accustomed to this tactic. The sequence of experiments was repeated on 36 damselfish colonies at three areas across the island.

This strongly means that trumpetfish shadow different varieties of fish to get nearer to their prey, says Matchette. “This is the first non-human example of an animal using another animal as camouflage to get close to or to conceal themselves from their prey,” he says. For instance, human hunters generally method birds resembling geese by crouching behind horses – that is the place the time period “stalking horses” comes from.

Rising sea temperatures may have an effect on the coral reef habitats that some fish reside in. “They are going to end up patchier, less complex and less biodiverse,” says Matchette. Fish species that depend on reefs for concealment from their prey might have to start out mimicking trumpetfish’s behaviour, which is vital for scientists to know as these ecosystems change. “If the ability to use the reef itself as cover is taken away, then maybe this alternative strategy of using other fish around your other organisms around you for cover might become more commonplace in the future,” he says.

“This is an excellent example of where a fascinating piece of observational natural history is turned into hard science by focused experimentation,” says Innes Cuthill on the University of Bristol, UK. It strongly means that trumpetfish swim carefully to fish resembling parrotfish to offer them a predatory benefit, somewhat than to offer them safety towards their very own predators, for instance, he says.