I read that it was because they don't have bones, they're moved by the rippling motion they make with their bodies. So, to save energy as they move from one food source to another, they make these long inertia trains to keep the ripple moving all the way through the line with minimal effort.
Of course, I read that on the internet, so it could be completely false.
Of course, I read that on the internet, so it could be completely false.