What is the scolex in a tapeworm?

• A. A larval form
• B. A feeding organ
• C. A reproductive organ
• D. A holdfast organ

Answer: (D)

The scolex is the holdfast region at the head of a tapeworm, specialized for attachment to the host’s intestinal wall. It carries attachment structures such as suckers and, in many species, a rostellum with hooks, allowing a firm grip so the worm can stay in place while nutrients are absorbed through its outer surface. Tapeworms lack a true digestive tract, so feeding isn’t done by a feeding organ—nutrients diffuse across the tegument instead. The scolex isn’t a larval form, since larval stages occur in intermediate hosts and the scolex is part of the adult worm. It also isn’t a reproductive organ; those functions are carried out by the proglottids along the body. Because its primary role is attachment, the scolex is best described as a holdfast organ.