The segmented worm, also known as an annelid, is a type of invertebrate characterized by its long, cylindrical body divided into segments. Each segment contains muscles and organs, allowing for efficient movement and flexibility. Common examples of segmented worms include earthworms and leeches. They play essential roles in ecosystems, such as improving soil structure and nutrient cycling. Segmented worms have a simple body plan, featuring a coelom, which is a fluid-filled cavity that provides support. They possess a nervous system and a closed circulatory system, which helps transport nutrients and oxygen. These worms can be found in various habitats, including soil, freshwater, and marine environments.