How Do Earthworms Egest?

There are more than 2,700 known species of earthworms, which are a type of segmented worm. Earthworms burrow through the soil all over the world, and the tunnels they leave behind provide passageways for valuable oxygen to flow beneath the Earth's surface and bring life and growth to underground animal and plant life. Water also travels through these passages to sustain life beneath the topsoil. Egestion is the process used to expel waste from the worm's body.

  1. Digestive Process

    • The first few segments of an earthworm's body are used for eating; the rest is made up of intestines for digesting the food, which may consist of decaying plant matter or organic matter such as insect casings, along with soil. While the first part of the worm's anatomy varies from the human digestive system---with a pharynx replacing the tongue and an organ called a crop that holds the ingested food rather than a stomach---the food enters the intestines after passing through the crop. Worm intestines pull nutrients the worm needs out of the food in the same way human intestines do. Enzymes produced by the worm break down much of the food, rather than intestinal bacteria. From the intestines, waste passes out through the worm's anus.

    Nondigestive Egestion

    • Worms have an excretory system in addition to the digestive system. In this system, fluids pass through tiny tubules called nephridia and into organs similar to your bladder. Any liquid that remains after the nutrients the worm needs are absorbed is excreted through pores in the worm's skin.

    Worm Poop

    • The proper term for earthworm droppings---colloquially known as worm poop---is "castings." These castings are full of vital nutrients, such as magnesium, calcium, phosphorus and nitrogen, all of which contribute to plant and animal life. The droppings are made up of ingested soil as well as other food sources. For every cultivated acre of land, between 16,000 and 30,000 lbs. of soil pass through worm intestines and are redeposited in the earth each year, according to Backyard Nature.

    Vernicomposting

    • Vernicomposting is a special type of composting that uses worm egestion as a tool to recycle a variety of waste types back into the environment as nutrient-rich soil. A species of earthworms known as redworms or red wrigglers may be placed in a composting bin outfitted with biodegradable bedding, air circulation and moisture. The worms will eat any organic material added to the bin and egest compost that can be beneficial for gardens. Some cities and counties have vernicomposting programs available through their waste disposal companies. Unlike regular compost bins, vernicomposting bins can handle meat, dairy and paper scraps.

    Fun Facts

    • It takes about 20 hours for an earthworm to egest food while feeding, but only slightly more than half that time (12 hours) to egest while creating burrows. Earthworms have five hearts and are hermaphroditic, meaning each worm has both male and female reproductive organs.