Worm is a tubular segmented worm found in the Annelida door. Common usually lives in the soil and feeds on living and dead organic matter. Worm's digestive system runs through its entire body. It breathes through the skin. It has a double delivery system and a simple, closed blood circulation system. The double delivery system is composed of the fluid accumulated in the cavity which is filled with liquid. It has central and peripheral nervous systems. The central nervous system is composed of two ganglia above the mouth, one on each side, which are connected to the nerve cord extending backward along its length, so as to move neurons and sense cells in each segment. A large number of chemoreceptors are concentrated near the mouth. The peripheral and longitudinal muscles of each segment enable the worm to move. Similar muscle groups are located in the gut, and their actions move the digested food toward the anus of the worm.

Are is hermaphroditic: everyone carries both male and female sex organs. As invertebrates, they lack internal skeleton or exoskeleton, but they maintain their structure through fluid filled chambers, which act as hydrostatic skeleton.

"Earthworm" is the generic name of the largest member of the Oligochaeta (depending on the author, whether it is a class or a subclass). In the classical system, although the internal male segments are in front of the female, they are placed in the order of Opisthopora according to the opening order of the male pores after the female. Theoretical studies have placed them in the order of the lambricina subsets of haplotypes, but this may change soon. The common names of for include dewbug, rain bug, night crawler and angle bug (because they are used as bait).

The larger terrestrial also is also known as megadrile, while in the semi aquatic family (tubificidae, Lumbricidae and Enchytraeidae, etc.), the micro (("small worm") is the opposite. Giant droplets are characterized by a distinct oblique (wider than a fine droplet) and a vascular system with real capillaries.

Disturbs are much less numerous in disturbed environments and are usually active only when there is water.