The ancylostoma is also known as hook worm. It acts as a parasite in the small intestine of man with no intermediate host. There are sharp cutting teeth present on the buccal capsule of the hook worm. They cut the inner lining of intestine and suck blood along with lymph. Their larvae enter in the humans from moist soil. They show sexual dimorphism. The female is longer and straight while the male is short and curved. The females have separate anus and genital aperture and these openings are combined in the males. They cause acute anemia along with the mental and physical deficiency. It leads to anclyostomiasis and this disease is more common in rural areas.