To most of us it has always seemed obvious that an octopus has eight arms. But experts have now revealed that this assumption is wrong - as two of their long tentacle-like limbs are in fact legs. A study by scientists at Sea Life centres across Europe found that the invertebrates move across the sea bed using their two rearmost limbs, leaving the other six free for the important business of feeding.
Researchers who observed the creatures in action found they push off with the "legs" and then employ the other tentacles to pump themselves along. Scientists from 20 centres across Europe analysed data from 2,000 observations of common octopuses to get the results.
"Observations showed that they use the rearmost two to get around over rocks and the seabed. They also use these two legs to push off when they wish to swim, and then other tentacles are used to propel them."