Australasian Science: Australia's authority on science since 1938

Eels in Knots over Food

The unusual feeding behaviour of moray eels, which includes co­operation with other fish to flush prey from reefs and crawling onto land to scavenge for dead fish, is more extensive than previously thought.

Underwater video captured at Scott Reef near Broome in Western Australia has recorded one moray tying its body into a knot to extract food from a bait bag, while another moray used its tail like a paddle to dislodge the food.

Lead author of the study, PhD student Shanta Barley of The University of Western Australia, said morays have traditionally been observed using knots to compress or break large prey into more manageable sizes, and to anchor food while they consume it. However, the use of a fast-moving knot to dislodge food has never before been observed, nor have they been seen to use their tails as paddles to exert force on a prey item.

“Our observations suggest that having an eel-like body shape opens the door to unusual and useful feeding techniques unavailable to conventionally shaped fish,” Barley said.

“Like moray eels, a group of subterranean, limbless amphibians known as caecilians are also known to rotate rapidly to twist pieces of flesh off oversized prey. The deep sea hagfish also use knots to pry prey out of burrows on the sea floor.”

Barley said the ability of morays to attack and consume prey much larger than themselves might explain the significant role of moray eels as a mesopredator in reef systems and the evolution of cooperative hunting partnerships with other large fish-eating species.

“There are questions that remain, such as to what extent can moray eels develop new behaviour when faced with unfamiliar situations, and whether the behaviour is passed on between eels in the same population like ‘songs’ in humpback whales,” Barley said.

“Moray eels are facing growing fishing pressure in certain parts of Indonesia. This is worrying as these predators, like sharks, may play a key role in regulating the abundance and behaviour of fish in coral reefs.”

The research has been published in Marine Biodiversity (www.tinyurl.com/plrr29q).