So why do crabs walk sideways when most other creatures walk forwards? It is easy for us humans to move in pretty much any direction, this is because of how our legs are attached to our bodies. Our knees facing towards the front makes walking forward way easier than sideways. But what about crabs, do they all walk sideways? 

A crab’s legs are attached to the side of its body. Its joints unlike our knees bend towards the sides which leaves the crab able to only walk one direction.

BUT there are some exceptions to this rule, Spider Crabs and Decorator Crabs.

Decorator Crabs are not flattened like the 'ordinary' crabs, but they have more rounded pear-shaped bodies. Instead of walking sideways, they can also walk forward. Decorator Crabs get their names from their ability to decorate their backs with snipped-off fragments of local seaweeds in order to blend in with their environment. Halimeda Crabs are one of these oddities that you may find along the KwaZulu-Natal North Coast, they have incredible camouflage making them seem a lot less common than they probably are.