Wheel Wearers: Cycliophora

IN WITH THE NEW OUT WITH THE OLD

A bud forms inside a feeding-stage wheel wearer. Inside this bud, a new set of organs, including the digestive system, nervous system, and mouth funnel, starts to develop. When fully developed, the new organs slowly move forward and push out all the old organs, until the new funnel can emerge through the neck and replace the old one. The only parts of the old wheel wearer that are used again are the trunk and the attachment disk. A feeding-stage wheel wearer can repeat this self-renewal process several times, and scientists are uncertain why it is necessary. Some believe that because the feeding-stage animals do not have a waste-removal system, waste accumulates, and the self-renewal enables the animal to eliminate these wastes before they become toxic.