IT doesn't really jump.....but the ball of spines will fall off the cactus if you brush up against it. The spines will impale you. Also watch your pets around these things. IT is pretty painful. So best thing to do is give them a wide berth. These things seem as if they are magnetically drawn to you. A good tip is to carry a fork in your backpack to use as a tool to remove these from whatever they stick to. Otherwise whoever is picking gets impaled too!
Nasty critter!