Not at all. They do grow back, albeit a little faster than hair. Genetics also factor into length such as where on the homeworld Shiva originated. The ones closer to large bodies had bigger ones and bluer skin, trend continues like that till you have a set of genetics where the thing isn't much larger than a foot. Their purpose is to swim faster or stab things, the military doesn't regulate length as that wouldn't be at all fair. They take like 1-4 months to grow back depending on length and genetics and such.