Friday, September 2, 2011

Dolphin Fish-Eating Trick Catches On

So many great articles from DiscoveryNews lately that I feel totally inundated--and nerdy. Did I mention nerdy? ;)

Photo by NASA, Courtesy of Wikipedia Commons
Dolphin Fish-Eating Trick Catches On
Analysis by Jennifer Viegas
Wed Aug 31, 2011 08:09 AM ET


Humans may have invented the spork, often seen at fast food joints, but a very clever group of bottlenose dolphins in Australia has created its own new combo tool that both captures fish and functions as a food bowl.

Use of the tool, described in a Murdoch University press release, is called "conching." Dolphins first trap small fish in large conch shells with their rostrums (beaks). They then bring the shells to the surface and shake them. Like a strainer, this causes the water to drain out and sends the fish right into the dolphin's mouth.

This isn't the first time dolphins have converted a natural item into a useful tool. For example, you might recall the journal paper from a few years ago describing how dolphins use sponges to protect their beaks and to help with fishing.

What's particularly interesting about this latest news is that the conching tool and technique appear to be spreading throughout a population of dolphins at Shark Bay, Australia. Scientists first observed dolphins engaging in these behaviors in 2007 and 2009.

Now many people are seeing dolphins conching.

"In the last four months alone, the research team have seen and photographed the behavior no less than six times, possibly even seven," Murdoch Cetacean Research Unit researcher Simon Allen was quoted as saying in the press release.

"If -- and that is a big if -- we are witnessing the horizontal spread of this behavior, then I would assume that it spreads by an associate of a 'conching' dolphin closely observing the behavior and then imitating it," he added. "It is a tantalising possibility that this behavior could spread before our very eyes -- over a field season or two -- and that we could track that spread."

No one has ever before documented the spread of a learned behavior through a population of these marine mammals over a short period of time.

The researchers also hope to learn more about how the dolphins actually use the shells.

"As yet, we don't know if dolphins simply pursue fish into the' refuge' of the large, empty conch/bailer shells or whether they actually manipulate the shells prior -- perhaps turning them over so that the opening is facing up in order to make them 'appealing' to fish as a place to hide from the jaws of death," Allen explained.

He continued, "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."

"I wouldn't be too surprised to find such cunning and devilish ploys being adopted by Shark Bay's bottlenose dolphins."

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