Dolphins Teach Their Peers Innovative Hunting Techniques

Dolphins have been observed chasing small fish into empty shells, bringing these shells to the surface and draining the water until the fish fall into their waiting mouths. Normally such behaviours would be taught to them by their mothers, but it has been shown in a study published in Current Biology that, instead, they learn this particular technique from their peers.

A number of surveys were carried out by Sonja Wild and her colleagues from the Univeristy of Leeds between 2007 and 2018. During this time, they were observing Indo-Pacific bottlenose dolphins (Tursiops aduncus) at the Dolphin Innovation Project's field site in Shark Bay, Western Australia and witnessed 19 dolphins, belonging to three maternal lineages, performing that same hunting technique, known as "shelling."

The team were surprised to see that the technique was learned on a peer to peer basis. "Dolphins normally learn foraging behaviour from their mothers, but we found that shelling spreads among closely associated individuals outside the mother-calf bond," Wild told New Scientist.

This not only shows that dolphins are able to learn from their peers, but also that they are motivated to do so. It highlights a parallel between dolphins and our closest relatives, the great apes, since chimpanzees also learn tool use from their peers. As such, the team's observations reveal interesting implications on how dolphin communities function.

As Séverine Methion of the Bottlenose Dolphin Institute in Spain explains, "Behavioural studies show that bottlenose dolphins have distinct personalities, self-awareness, and complex social structures, with individuals cooperating and with new behaviours like shelling being passed from one dolphin to another. In a broad context, this transmission of information could be considered culture."

The ability to learn from others is important in helping animals adapt to changing environments and, as is the case here, spreading new behaviours that allow individuals to forage even under conditions where food may be scarce. The research team observed that shelling was more frequent in the dolphins following a heatwave, as the increased death rate in giant gastropods meant that more shells were readily available for them.

This is not the first time that foraging tool use has been witnessed in dolphins. They have also been observed using sponges to cover their beaks, allowing them to effectively dig into the seabed in search of prey. This behaviour was first recorded in the 1980s and was later studied by Dr Janet Mann and her colleagues who published their findings in PLoS One in 2008.

A sponge similar to what would be utilised by dolphins during "sponging."

So far, shelling has only been observed in Indo-Pacific bottlenose dolphins. However, it is entirely possible that this behaviour occurs in other dolphin species and has yet to be witnessed. The team's findings provide exciting potential for future studies that could help us learn more about dolphin behaviour and, more specifically, the ways in which they interact and learn from one another.