Study reveals use of tools by octopuses
Researchers often see tool use as a mark of intelligence. Humans, birds, primates and other mammals are all known to use them, and now a report by British and Australian researchers published in the journal Current Biology says that octopuses, an invertebrate, can be added to the list. Until recently, science had perceived invertebrates as lacking the cognitive abilities to demonstrate tool use. While some have been observed using leaves or sand to collect and transport food, researchers have said that these behaviours are different to the tool use seen in mammals and birds. The new report details a type of behaviour of the veined octopus called 'stilt walking': the soft-bodied octopus spreads itself over stacked, upright coconut shells, makes its eight arms rigid, and raises the whole assembly to then amble across the seafloor. The octopus later uses the shells as a shelter, which the researchers say is different to a hermit crab using a discarded shell. 'There is a fundamental difference between picking up a nearby object and putting it over your head,' said Mark Norman of the Museum Victoria in Australia, who worked on the project and led the report, 'versus collecting, arranging, transporting (awkwardly) and assembling portable armour as required.' The researchers found that the veined octopus exhibits further tool abilities by assembling the coconuts. This confirms the behaviour as tool use, distinguishing it from other object manipulations by octopuses, such as using rocks to barricade a lair entrance. To study the octopuses, researchers dove for nearly 500 hours between 1999 and 2008 off the coasts of Bali and northern Sulawesi in Indonesia. More than 20 octopuses were studied, and the discovery of the behaviour was a surprise. 'I could tell that the octopus, busy manipulating coconut shells, was up to something, but I never expected it would pick up the stacked shells and run away,' stated Julian Finn, also of the Museum Victoria. 'It was an extremely comical sight - I have never laughed so hard underwater.' The researchers believe that the behaviour is likely to have evolved using large empty bivalve shells prior to the relatively recent supply of clean and light coconut shell halves discarded by costal communities near the marine habitant of the octopuses. The report concludes: 'Ultimately, the collection of use of objects by animals is likely to form a continuum stretching from insects to primates, with the definition of tools. However, the discovery of this octopus tiptoeing across the seafloor with its prized coconuts shells suggests that even marine invertebrates engage in behaviours that we once thought the preserve of humans.'
Countries
Australia, United Kingdom