Hookworm parasite. Light micrograph of the rear end of Ancylostoma caninum, a parasitic hookworm which affects cats and dogs. This species of nematode worm is unable to mature in humans but the larvae often causes lesions in the skin. The hookworm larvae live in soil and water, mainly in the warm, moist tropics. They enter a host by boring through the skin. Once within the body they migrate, via the lungs, to the intestines. Here they secure themselves with hooks around their mouthparts to the intestinal wall and suck blood from their host. They release thousands of eggs each day which pass out of the host with the feces. Magnification: x18 at 35mm size.