Segmented worms (Anelids) are so called because their bodies are made up of segments which are helpful with locomotion. There are marine and terrestrial species. The most common land segmented worm are earthworms. The marine worms are called polychaetes and I think were the inspiration for the Jormungars that showed up in Northrend. There are over 22,000 species of segmented worms. They make interesting hunter pets and are animated beautifully when they swim.