o hai octopi | tool use in cephalopods
Bio 342 Fall 2011
Tool use, once thought to be the defining characteristic of humanity, has now been demonstrated in a number of other vertebrate species including chimpanzees, dolphins, elephants, and many species of birds. But cephalopods!? They have more nerves in their arms than their brains! Our closest common ancestor is an urbilaterian! As shocking as it is, the rumors are true: octopi are the latest newcomers to the elite club of tool users. For cephalopods, true tool use is only found in Amphioctopus marginatus, or the veined octopus, which uses a behavioral trick called stilt walking in order to carry coconut shell halves discarded by the human populations of Northern Sulaweski and Bali in Indonesia . After transporting the coconuts, the octopus uses them as a shelter to defend against predators.
This video shows a veined octopus flushing out buried coconuts from the mud, stilt walking, and hiding under the shell for defense.
What constitutes tool use?
The definition of tool use is controversial. A liberal definition might be “the use of an object to achieve a goal.” A strict definition of tool use requires the acquisition of an item that has an immediate cost to the animal but has a deferred benefit upon its use. This strict definition would weed out instances of octopi manipulating their environments through den barricading with rocks/coral, for example.
What is the significance of tool use?
Tool use has long been considered an indicator of rational thought because it involves complex cognitive processes, such as planning, problem-solving, and manipulating an environment. For our purposes, we will bracket these larger philosophical discussions, but it is important to realize the potential implications for this cephalopod behavior.
The Bigger Picture: Cephalopod Intelligence
True tool use is but one example of many instances of cephalopod intelligence. These creatures can navigate mazes, open jars, and modify their homes using found objects. Perhaps they are even psychic (joke)! As we explicate the coconut-carrying behavior throughout this site, we will couch our discussion in this larger picture, drawing heavily on octopus' cognitive capabilities.
Because there is only one published study on coconut-carrying behavior in octopuses (presumably due to its recent development in response to a change in environment brought on by human activity), we have drawn heavily on research involving other cephalopods, especially O. vulgaris (the common octopus) which is the most-studied of the octopods. There is a high degree of continuity in behavior across the Octopus genus, and although Amphioctopus marginatus is technically in a different genus, they are still reasonably similar.
We will explore this behavior using Niko Tinbergen's Four Questions: