Eisenia fetida

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Eisenia fetida
Scientific classification
Kingdom: Animalia
Phylum: Annelida
Class: Clitellata
Order: Haplotaxida
Family: Lumbricidae
Genus: Eisenia
Species: E. foetida
Binomial name
Eisenia foetida
(Savigny, 1826) [1]

Eisenia fetida (older spelling: foetida), known under various common names such as redworm, brandling worm, panfish worm, trout worm, tiger worm, red wiggler worm, red californian earth worm, etc., is a species of earthworm adapted to decaying organic material. These worms thrive in rotting vegetation, compost, and manure; they are epigean. They are rarely found in soil, instead preferring conditions that are inimical to some other worms. In this trait they resemble Lumbricus rubellus.

They have groups of bristles (called setae) on each segment that move in and out to grip nearby surfaces as the worms stretch and contract their muscles to push themselves forward or backward.

Eisenia fetida worms are used for vermicomposting. They are native to Europe, but have been introduced (both intentionally and unintentionally) to every other continent except Antarctica.

Odor

When roughly handled, an eisenia fetida exudes a pungent liquid, thus the specific name foetida meaning foul-smelling. This is presumably an antipredator adaptation.

Close-up of Eisenia fetida with visible bristles

Related species

Eisenia fetida is closely related to Eisenia andrei, also referred to as E. foetida andrei. The only simple way of distinguishing the two species is that E. foetida is sometimes lighter in colour. Molecular analyses have confirmed their identity as separate species and breeding experiments have shown that they do not produce hybrids.

Reproduction

As with other earthworm species, Eisenia fetida is hermaphroditic. However, two worms are still required for reproduction. The two worms join clitella, the large lighter-colored bands which contain the worms' reproductive organs, and which are only prominent during the reproduction process. The two worms exchange sperm. Both worms then secrete cocoons which contain several eggs each. These cocoons are lemon-shaped and are pale yellow at first, becoming more brownish as the worms inside become mature. These cocoons are clearly visible to the naked eye.

References