Earthworm
Earthworm
Earthworm (/ˈɜːrθwɜːrm/), also known as lumbricus terrestris in scientific terms, is a tube-shaped, segmented worm found in the phylum Annelida. They are commonly found living in soil, feeding on live and dead organic matter.
Etymology
The term "earthworm" is derived from the Old English words "eor(th)e", meaning "earth", and "worm", meaning "serpent" or "dragon". The scientific name, Lumbricus terrestris, is Latin for "earthly worm".
Anatomy
An earthworm's body is made up of ring-like segments known as metameres. Each segment or metamere is separated from its adjacent segments by a partition known as a septum. The "head" end of the worm, the anterior, contains the mouth. The "tail" end, the posterior, is used for excretion.
Physiology
Earthworms have a dual circulatory system, meaning they have both a circulatory system and a coelomic fluid that circulates within the body cavity or coelom. They also have a simple brain that connects with nerves from their skin and muscles, and their nervous system is controlled by a ventral nerve cord.
Reproduction
Earthworms are hermaphrodites, meaning each individual carries both male and female sex organs. They reproduce by aligning their bodies and exchanging sperm with another earthworm. Fertilized eggs are deposited into a cocoon, which is then released into the environment.
Ecological Role
Earthworms play a vital role in soil health. They are known as "ecosystem engineers" as they significantly influence the structure of soils and availability of soil nutrients. They contribute to the decomposition of organic matter and the recycling of nutrients in the soil.
Related Terms
- Annelida: The phylum to which earthworms belong.
- Metamere: The ring-like segments of an earthworm's body.
- Septum: The partition separating the segments of an earthworm's body.
- Anterior: The "head" end of the worm.
- Posterior: The "tail" end of the worm.
- Circulatory system: One of the two systems used by earthworms for circulation.
- Coelom: The body cavity within which the coelomic fluid circulates.
- Ventral nerve cord: The structure controlling the earthworm's nervous system.
External links
- Medical encyclopedia article on Earthworm
- Wikipedia's article - Earthworm
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