Senses

While I was discussing with my friends, we came across some little theory. You know how we have five senses? Well, what if there are actually thousands of senses out there and we only use five of them. For example, there are a species of gecko that live in a cave and they are completely blind. If you think about it, since they never use sight, they don't know what sight is. They only have four senses that we know of. Like the gecko, we would only know five senses, but the world is full of senses that we don't know of. For example, we already know of a couple more senses we don't have. A shark for instance can sense electromagnetic waves through it's epidermis. There are many more things we have to know about this world.