Adult Hymenolepis diminuta reach 20 to 60 cm, and up to 90 cm . The cestode has a long cylindrical body with 4 suckers and an apical organ at its scolex with no rostellar hooks. Hymenolepis diminuta, along with all cestodes, lacks any trace of a digestive tract, and it absorbs all required substances through its external covering. Posteriorly directed microtriches cover the cestode's tegument, which add to the surface area of the animal and thus to the amount of nutrients it can absorb.
Hymenolepis diminuta, like all other cestodes, has three body sections, a scolex (head), neck, and a strobilus, which is the rest of the cestodes body. The strobilus is divided into many sections called proglottids, each with male and female sexual organs. These are the defining characteristics of cestodes.
Range length: 20 to 60 cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry