To many creatures the human body is a landscape. Countless numbers dwell in its undulating hills, deep caverns and thick forests. Butterflies visit us for a salty cocktail of sweat. Mosquitoes follow breath trails, ticks wait for us to find shade and fleas jump on board at the slightest vibration. In the jungle of our hairs, lice find a home, mites inhabit crevices and on the desert of our skin, bacteria multiply undisturbed. Inside the body creatures travel among swirling blood cells while others share our meals.