Hidden in plain sight: Brilliant hunting strategy of trumpetfish revealed

In the vibrant world of coral reefs, a peculiar strategy of hunting has emerged, shedding light on the surprising lengths predators go to for a successful hunt. This strategy, known as “shadowing,” has been observed in the trumpetfish, Aulostomus maculatus. 

Through an intensive study, a team of scientists led by the University of Cambridge has discovered that this long, slender fish has a clever trick to approach its prey undetected: it hides behind other fish.

“When a trumpetfish swims closely alongside another species of fish, it’s either hidden from its’ prey entirely, or seen but not recognized as a predator because the shape is different,” explained Dr. Sam Matchette, who led the study. 

This innovative method is comparable to nature’s own game of hide and seek, where the predator hides in plain sight.

How the research was conducted 

Through painstaking efforts involving countless hours diving in the Caribbean Sea, researchers utilized hand-painted model fish, which they pulled along wires to simulate the movement of real fish. 

Among their primary subjects of observation were the damselfish, Stegastes partitus. These fish, a common delicacy for the trumpetfish, form colonies on the seafloor.

The trumpetfish’s unique approach was tested using 3D-printed models in the coral reefs off the Dutch Caribbean island of Curaçao. 

What the researchers discovered 

The study revealed that when a trumpetfish model, replicating its shadowing behavior, was attached to the side of a non-threatening parrotfish model, the damselfish did not recognize the looming threat. Instead, their reaction mirrored their response to the harmless parrotfish alone.

“I was surprised that the damselfish had such a profoundly different response to the different fish; it was great to watch this happening in real time,” said Dr. Matchette.

The findings, published in the journal Current Biology, are the result of a collaborative effort with researchers from the University of Bristol. 

Study co-author Professor Andy Radford emphasized the significance of such wild experiments: “Doing manipulative experiments in the wild like this allows us to test the ecological relevance of these behaviors.”

Intriguing observations

Interestingly, while earlier accounts from divers in the Caribbean had frequently reported observing trumpetfish swimming alongside parrotfish and other reef fish, the true reason behind such peculiar behavior had remained unexplored until now. 

Another intriguing observation was that the shadowing behavior was more common in degraded reefs, hinting at the possibility of an adaptive strategy in the face of environmental changes.

Animal adaptation 

With coral reefs globally facing challenges from rising temperatures, pollution, and overfishing, such behavioral strategies might play a pivotal role in animal adaptation. 

“The shadowing behavior of the trumpetfish appears to be a useful strategy to improve its hunting success. We might see this behavior becoming more common in the future as fewer structures on the reef are available for them to hide behind,” explained study senior author Dr. James Herbert-Read.

By comparison, human duck hunters once hid behind cardboard cut-outs of domestic animals, known as “stalking horses,” to approach their prey without detection. Yet, despite its significance, this strategy has remained largely understudied in the animal kingdom and has never been experimentally tested before, until now.

More about the trumpetfish 

The trumpetfish is a fascinating creature that is part of the marine life often found in tropical and subtropical waters.

Appearance

As the name suggests, trumpetfish have an elongated, tubular body similar to a trumpet. They can reach lengths of up to 3 feet. Their long snouts are used to suck out prey from crevices in the reef.

Color

Trumpetfish have the ability to change their color to blend in with their surroundings. They can be brown, green, blue, or yellow, and sometimes have vertical stripes to help them mimic vertical coral, like sea rods.

Habitat

They are usually found in shallow waters among reefs, often hiding among sea rods and whip corals or floating motionless, head-down, trying to blend in with their environment.

Diet

Trumpetfish are carnivorous and prey on small fish and crustaceans. Their slender, tubular bodies allow them to approach prey without being detected, and their long snouts help them quickly suck in unsuspecting victims.

Behavior

Trumpetfish are known for their unique hunting strategies. As the Cambridge study revealed, they employ a shadowing behavior where they stalk their prey by hiding behind larger fish. This is not their only strategy, however. They can also float vertically, camouflaging themselves as sea whips, to get closer to their prey.

Reproduction

Not much is known about the reproduction habits of the trumpetfish. They are oviparous, with females releasing eggs that are fertilized externally.

Distribution

They are found in the tropical regions of the Pacific and Atlantic Oceans, including the Caribbean.

Relation to humans

Trumpetfish are not generally considered dangerous to humans. They are sometimes captured for the aquarium trade due to their unique appearance and are occasionally used as food in certain cultures.

The trumpetfish, with its unique appearance and fascinating behavior, is a testament to the incredible adaptability and diversity of marine life. It serves as a reminder of the many mysteries the ocean holds and the importance of preserving marine ecosystems.

Video Credit: Sam Matchette

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