Sharks have no backbones

I was watching QI the other day and I learnt an interesting fact, sharks don't have backbones. Their skeleton is not made of bone but of cartilage. The reason for this is that it allows the shark's body to be more flexible, which enables it to have greater movement in the water. However, since their 'spine' is made of cartilage and not bone, I guess in essence you could consider a shark to be spineless. Now a spineless creature, to me, has always been defined as one lacking courage, a real coward. However, sharks are not considered to be lacking in courage, and are in fact a creature that instils fear and scares away cowards, so does this mean that we should redefine what spineless means?

I suppose when they created the term spineless they were thinking of creatures such as worms or snails, creatures that don't instil fear, and that hide away when they sense danger. The fact of the matter is though, that there are other spineless creatures that will attack rather than hide, such as the scorpion. So perhaps more work should have been done when creating the term spineless, to see if it is really an accurate portrayal of all spineless creatures. In this instance though, since this term is already in effect, I guess we just need to accept that they are wrong but let them have their way.