Annelids (animals belonging to the Annelid Phylum which is in the Animalia Kingdom) are segmented worms including earthworms, leeches, fireworms, Christmas Tree worms, and many other species. Having segments is one of the primary characteristics that separates annelid worms from flatworms and roundworms. These segments are rings that repeat all up and down the worm's body.Segmentation - Each segment in a segmented worm contains many of the same organs, including those used in digestion, movement, excretion (getting rid of waste), and circulation. In the photo above, you can easily see the individual segments of the worm.Septa - Septa are internal walls that separate the body segments. They can be found in most types of annelids. The worm's circulatory system allows nutrients and other things to be passed from one segment to another.Cerebral ganglion - A cerebral ganglion is a primitive brain that is located in a segment near the front of the worm.A nerve cord connected to the brain runs along the underside of an annelid's body. This nerve cord carries sensory information from the various segments to the worm's brain.Coelom - A coelom is a fluid filled cavity located between the gut and the body wall. The coelom of an annelid is a true coelom because it's located entirely within the mesoderm (muscle tissue). For more about the coelomMost annelids live in the ocean, but others, like the earthworm, live on land.Closed circulatory system - Like humans, annelids have a closed circulatory system. That means that the blood pumped by the heart is fully contained within the circulatory system and does not wash out into the tissues of the body.Annelids have highly specialized organs.Nephridia are excretory organs which remove wastes from the annelid's body.Setae are bristles that are located on each segment of some annelids. Setae help increase traction to make movement easier for the worm.Parapodiaare almost like a series of little feet. Parapodia are paired and unjointed appendages (things that stick out from the main part of the body are called appendages.). Some, but not all, annelids have parapodia.