- When and earth worm burrows itself in the ground it loosen the soil so that oxygen and water can penetrate it.
- Both surface and burrowing worms help to produce soil by mixing organic and mineral matter by making organic matter decompose faster making it available to other organizations.
- They are unable to migrate far on their own, however sometimes a worm or their cocoon gets caught on a shoe or the wheel of a vehicle and then transported wherever that goes.
- Unfortunately sometimes when they are brought to a place they are naturally not found they can sometimes negatively impact the place by invasive worms through the loss of leaf duff, soil fertility, changes in soil chemistry and the loss of ecological diversity.
- Marine annelids burrow increasing the penetration of water and oxygen into the sea-floor sediment, which encourages the growth of populations of aerobic bacteria and small animals alongside their burrows.
- Often blood-sucking leeches are not much harm to their hosts sometimes they can carry diseases.