Researchers from Australia and California have captured moray eels off the coast of Broome in Western Australia, which tie its body into a “knot” as a new, unique way to consume prey. The eel-like body shape allows the morays to have the “unusual and useful feeding techniques,” researchers say.

A video shows two moray eels at the Scott Reef, located off the coast of Broome, showing unusual behaviours to get a food at a bait bag underwater. One of the eels tie its body to remove the food from the bag, while another moray was used its tail as a “paddle” to get the item out.

The morays, according to the researchers, commonly use knots to compress or break large prey into manageable sizes and to anchor food while feeding. However, using their body as a fast-moving knot and a paddle to extract food was never been observed or seen, the researchers said.

“Our observations suggest that having an eel-like body shape opens the door to unusual and useful feeding techniques unavailable to conventionally shaped fish,” said Shanta Barley, lead author of the study and a PhD student from UWA’s Ocean Institute and School of Animal Biology. Moray eels are believed to be one of the most elusive and important predators that can help conserve life in coral reefs.

The ability of the morays to attack and consume prey that is much larger than it would allow the researchers to understand the important role of the species as a meso-predator in reef systems as well as the evolution of “cooperative hunting partnerships” it performs with other large fish-eating animals. The study was published on Oct 8, in the journal Marine Biodiversity and was funded by the University of Western Australia and the Australian Institute of Marine Science, or AIMS.

Scientists have also found other marine species that use knots as a predatory technique. Like moray eels, a deep sea hagfish ties itself into knots to spy prey in burrows on the seafloor, and a group of subterranean, limbless amphibians called “caecilians” rotate its body rapidly to twist pieces of flesh off oversized prey. But the researchers are still aiming to determine how unfamiliar situations would change or make the moray eels develop new behaviour, Barley said.

She added the question if the behaviour could be passed on between eels in the same population, “like ‘songs’ in humpback whales.” Moray eels are currently being affected by the growing fishing pressure in certain parts of Indonesia, which has been worrying for scientists as the eels belong to the type of predators, like sharks, that may be significant to regulate the abundance and behaviour of fish in coral reefs.

“At a time when humans are disturbing reef ecosystems at unprecedented levels, understanding species’ behaviour and flexibility can provide insights into their resilience,” said Professor Jessica Meeuwig, a co-author of the paper. The new study helped to enhance the understanding of the moray species with its unusual predatory behaviour, she added.

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