Another remarkable difference between humans and cockroaches is in their senses. Let's look at sight first. Humans only have one lens in each eye. With this many lenses, the cockroach is not able to focus on objects very well. Instead, cockroaches can see when an object is moving.
Cockroaches also have a very good sense of touch.
Their feet are so sensitive that cockroaches can detect when the ground vibrates less that one millionth of a millimeter. Similarly, cockroaches have two projections coming off their rear quarters called cerci which can detect air movements behind them. The cockroach's sharp senses are extremely useful since they can sense any predator trying to sneak up on them long before it arrives. A cockroach has blood, but it does not circulate through veins and arteries the way our blood does. Blood sloshes around inside the insect, but is moved by the heart.