Is an octopus right or left tentacled?

I read an interesting story the other day: marine biologists from 23 Sea Life centres across Europe are hoping to find out whether octopuses are left or right tentacled. During the study, the octopuses will be given a selection of toys including jars, balls, Leggo, and Rubik's cubes to see whether there’s one tentacle they prefer using over the others.

The results will be released in autumn.

Incidentally, I also read an octopus in a German zoo has been trained to open a jar!