What makes cats so jumpy?

There can be many things that can make cats jumpy. Cats have a 6th sense, they can sense energy that humans can't. A cat may start to act jumpy before an earthquake because they can sense the energy coming from miles away.

Another answer: Cats are very cautious and curious-your question is not specific enough to provide a good answer.

PS I wish there were some way to get these lines to go away...