Octopus arms: ask anyone how many arms an octopus has, and the answer will probably be eight. However, marine experts revealed this may be wrong as two of their long limbs function more as legs.
Although all the limbs basically have the same capabilities, the study by scientists at Sea Life centres across Europe found that the two rearmost octopus arms are largely for moving across the sea bed, leaving the other six free for feeding and exploration.
The octopuses were found to favour their front two limbs the most for exploratory work, while if further investigation was needed, those immideately behind them were also used. In this context, it is important to note that the limbs of the octopuses are not tentacles, which are much larger and have suckers at their tips only.
It may indeed be that the rear octopus arms are used more for propulsion, while the front legs are more for exploration. I think however that since all limbs are used for propulsion and for exploration, see the earlier post tool-using octopus, its too clear-cut to say octopuses have six arms and two legs.
Originally the study was designed to investigate if these fascinating invertebrates have a preferred arm. The octopuses were given a Rubix cube to explore. It was found that octopuses are ambidextrous, thus showing they are neither left- nor right “tentacled”. Interestingly, the giant pacific octopus, the largest species in the world (see this video) had the ability to move sections of the Rubix cube.