Adults of Onchocerca volvulus are long and slender, have a smooth cuticle, and have blunt anterior and posterior ends. There are no lips or buccal capsule, and the mouth is surrounded by 2 circles made up of four papillae each. The esophagus doesn't appear to be divided. Males range in length from 19-42 cm and range in width from 130-210 micrometers. Lacking alae, their tails are curled ventrally and bear 6 or 8 pairs of postanal and 4 pairs of adanal papillae. Females are larger than males, ranging in length from 33.5-50 cm and in width from 270-400 micrometers. Their vulva is directly behind the posterior end of the esophagus. The microfilariae released by adult females are 250-300 micrometers long, are unsheathed, and have sharply pointed and curved tails.
Range length: 19 to 50 cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger