Dolphin Tools?

It is not often that we see nonhuman animals utilizing tools for different activities. The woodpecker finch uses cactus needles to get at food, and chimps have been observed fashioning tools to reach termites in their holes. But to think even marine animals learn to find and use tools seems pretty far-fetched.

Recently, researchers, including Michael Krützen from the University of Zurich, have noticed dolphins in Australia's Shark Bay using sponges to cover their sensitive snouts while searching for food along the ocean floor. The sponges protect the dolphin from sharp rocks along the bottom as well as from bottom-dwelling animals that can sting the dolphin as it searches for food.

Krützen and his collegues had a few hypotheses for the transmission of this behavior. To date, this 172 dolphins of Shark Bay are the only known to do the behavior and show the first observation of tool use in dolphin species. The behavior was found to have a female bias, with 1 male and 12 females exhibiting the behavior. Due to the action being found in what appeared to be a lineage from a single female bottleneck, they thought the behavior could be passed on genetically. Researchers ruled out environmental factors being a cause due to the dolphins using the sponges living with and among those that did not. Lastly, they questioned if the behavior was a result of cultural learning.

After extensive genetic testing of the lineage of sponge utilizers, researchers found that they all shared genetic markers from the maternal lineage, but this did not provide an answer to why the behavior was typically found in females. By ruling out their other hypotheses, the researchers concluded the behavior was being passed through cultural learning among some females in the Shark Bay population.

Posted by Courtney Huffman (6)


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