Anoplans and Enoplans: Nemertea

Most anoplans and enoplans live alone. They glide with the help of hairlike fibers on their belly and mucus they produce. Some species swim with wavy movements, but only for a short time. Most anoplans and enoplans have separate sexes. They reproduce by releasing their eggs and sperm into the water. Fertilization (FUR-teh-lih-ZAY-shun), or the joining of egg and sperm to start development, takes place and larvae develop outside the body. In some species fertilized (FUR-teh-lyzed) eggs are deposited in a jelly-like cocoon in which the larvae develop. In a few species eggs are fertilized inside the female, and the young are born looking like small adults rather than as larvae.