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.
Along the side of a cockroach's body are tiny holes called spiracles. Oxygen enters the cockroach through these holes and follows the tiny breathing tubes called tracheae to all of the cockroach's body parts. Humans have skeletal systems which function to provide the structural support necessary to support their bodies. Insects are surrounded by a hard covering called an exoskeleton. This shield serves as both a structural and protective armor.