Tapeworm head. Coloured scanning electron micrograph of the head (scolex) of a tapeworm (Taenia pisiformis), showing the hooks used to attach to the host animal’s digestive tract. Tapeworms are parasites that live in animal intestines feeding off the food ingested by the host. Adults of this species may reach up to 200 centimetres in length. Magnification: x100 when printed 10 centimetres wide.