Fishing with conch shells is catching on
A dolphin catches fish with her new tool. Photo from Murdoch University
It’s all the rage among bottlenose dolphins in Shark Bay, Australia: catching fish with a conch shell.
But this discovery is doubly exciting to scientists, because it isn’t just another new example of how dolphins use tools in their daily lives; it’s also a demonstration of how a new idea can spread through the dolphin community by being passed on from one family to another. And that’s the definition of what we call culture.
Four years ago, scientists at Murdoch University in Western Australia began noticing dolphins carrying large conch shells in their mouths to trap small fish. They would then bring the shells to the surface and shake them, causing the water to drain out and the fish to fall into their mouths.
Simon Allen of Murdoch’s Cetacean Research Unit says the technique appears to be spreading.
“In the last four months alone,” he said, “the research team have seen and photographed the behavior no less than six times, possibly even seven.”
If it’s confirmed that this behavior is spreading among families, this would be a further demonstration of dolphin culture.
“It is a tantalizing possibility that this behavior could spread before our very eyes – over a field season or two – and that we could track that spread,” Allen said.
The prospect of observing a learned behavior spreading through a population over a short period of time is exciting in itself, but the behavior also raises new questions about how exactly dolphins engage in conching.
The researchers don’t know exactly how the dolphins are catching the fish in the shells. One possibility is that they lay the shells with the opening face-up in order to make them look like a good place for fish to hide.
“If we were to set up a few shells – opening down – in a known location and either witness dolphins turning them over, see evidence of them having been turned over when we weren’t around, or better still get some video footage of dolphins manipulating them in some way, then that would be priceless, since that implies forward planning on the dolphins’ part,” Allen said.
Until such observations are recorded though, Allen says it is too early to rush to any conclusions. But the team is excited.
“I wouldn’t be too surprised to find such cunning and devilish ploys being adopted by Shark Bay’s bottlenose dolphins,” he said.
Dolphin culture has been observed in many other ways. For example, an injured dolphin, who was taken to a theme park briefly for treatment, was later seen back out in the ocean teaching her family how to tail-walk, after seeing the captive dolphins doing it.
And other dolphins have been seen using sponges to scour the ocean floor without hurting their beaks.
What do you say? Have you observed animals teaching new tricks and behavior to their families or friends? What about your own pets, even? Let us know in a comment or on Facebook.