Kinorhynchs: Kinorhyncha

Kinorhynchs move by contracting the muscles on the top and bottom of their body. The contraction increases pressure on the fluid in the trunk. This process plows the spines into the sand or mud and pushes the worm forward, at the same time forcing its head out of the trunk. When the worm relaxes its muscles, the head is pulled back into the trunk.

Kinorhynchs collect diatoms by using their rigid bristles as tweezers to pinch an end of the diatom's shell, manipulate the diatom into their mouth, and break the shell. Then they suck out the insides.

Kinorhynchs have separate sexes. A male places a bag of sperm in a female, where fertilization (FUR-teh-lih-ZAY-shun), or the joining of egg and sperm to start development, takes place. The female then attaches the egg sac to sand grains. In about ten days the young kinorhynchs tear open the egg sac by straightening their bodies and thrusting out their heads. Young kinorhynchs shed their outer layer five or six times before reaching adult size.