A NEW TOOL

Spong­ing may not be the only way that dol­phins in Shark Bay are be­ing in­no­va­tive with props for for­ag­ing.

Australian Geographic - - Geo buzz -

In 2007 re­searchers be­gan to spot them reg­u­larly in the western gulf of the bay do­ing some­thing odd with the mas­sive shells of Aus­tralian trum­pet snails, which are the world’s big­gest gas­tropods.

“We had no idea what was go­ing on,” says Dr Si­mon Allen, a dol­phin bi­ol­o­gist at the Univer­sity of Western Aus­tralia (UWA) in Perth, who works along­side Richard Con­nor (now Pro­fes­sor of Bi­ol­ogy at the Univer­sity of Mas­sachusetts) as part of the Shark Bay Dol­phin Re­search Al­liance project. “A dol­phin just ap­peared with a mas­sive trum­pet shell and was shak­ing it about. We won­dered if it was play­ing or show­ing off to its mates. But then later that day, we looked at the pho­tos and saw wa­ter fall­ing out and then a fish, and re­alised this had the po­ten­tial to be an­other very clever tech­nique for ob­tain­ing food.”

In the past decade, Si­mon and his col­leagues have since ob­served ‘shelling’ (see be­low) 30–35 times. It may be that the dol­phins un­in­ten­tion­ally chase fish into shells on the sea floor and have learnt to get the fish out by car­ry­ing the shells to the sur­face and drain­ing them of wa­ter. A more ex­cit­ing pos­si­bil­ity is that they are in­ten­tion­ally chas­ing fish into shells and us­ing them like traps, Janet says, as hu­man hun­ters do. If that turns out to be the case, it will defini­tively count as an ad­vanced form of tool use.

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