Hookworms (Ancylostoma caninum) are a species of roundworm in the phylum Nematoda. They live off of a host by attaching to the stomach or underside of another animal and eating out their intestines. They have a straight body, but their heads are curved, giving them the name "hookworm". When a hookworm infects an organism, it drains the blood from both intestines and causes bloody stool. They can live in almost any environment but are mostly found in the desert. They use cilia on the epidermis and layers of muscle that run the length of the body to help them move around. They have longitudinal body symmetry. The muscles are alerted by two nerves that run the length of the body, like the muscles themselves. The nerves and muscles are very close together.