The European nightcrawler (''Dendrobaena hortensis'') is a medium-small

earthworm An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. T ...

averaging about 1.5 g when fully grown. Generally blueish, pink-grey in color with a banded or striped appearance, the tips of their tails are often cream or pale yellow. When the species has not been feeding, it is pale pink. The species is usually found in deep woodland litter and garden

soils Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ter ...

that are rich in organic matter in European countries. ''D. hortensis'' is sold primarily as a bait worm, but its popularity as a composting worm is increasing. It was considered part of '' Eisenia'' until 2003. It is also formerly considered part of the similar '' Dendrobaena veneta'', but now just part of the

species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

. Both are useful compost worms. The two species are probably not distinguished in

vermicomposting Vermicompost (vermi-compost) is the product of the decomposition process using various species of worms, usually red wigglers, white worms, and other earthworms, to create a mixture of decomposing vegetable or food waste, bedding materials, and ...

. In general, the ''E. hortensis'' name is more common in North America while the ''D. veneta'' name is more common in Europe.

Etymology

The former genus ''Eisenia'' is named after Swedish scientist Gustav Eisen. According to the

International Code of Zoological Nomenclature The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its publisher, the ...

, the

specific Specific may refer to: * Specificity (disambiguation) * Specific, a cure or therapy for a specific illness Law * Specific deterrence, focussed on an individual * Specific finding, intermediate verdict used by a jury in determining the fina ...

name ''hortensis'' ("of the garden") is derived from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''hortus'' meaning "garden". The other specific epithet ''veneta'' refers to the Veneto region, a region of northern Italy.

Usage

Compared to ''

Eisenia fetida ''Eisenia fetida'', known under various common names such as manure worm, redworm, brandling worm, panfish worm, trout worm, tiger worm, red wiggler worm, etc., is a species of earthworm adapted to decaying organic material. These worms thrive i ...

'', ''D. hortensis'' does best in an environment with a higher carbon to nitrogen ratio. This makes it well suited to compost pits high in fibrous materials commonly known as browns. European nightcrawlers can be invasive and should be used only in contained compost systems in parts of the world with northern deciduous and boreal forest ecosystems.

Reproduction

''D. hortensis'', as a hermaphrodite, has both male and female reproductive organs. In mating, the weaker partner is forced into the female role, which is more expensive in terms of biological reproduction costs, for a sperm cell is generally less massive and energy-demanding than an ovum (egg cell), which is the female reproductive cell (

gamete A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce ...

) in

anisogamous Different forms of anisogamy: A) anisogamy of motile cells, B) egg_cell.html"_;"title="oogamy_(egg_cell">oogamy_(egg_cell_and_sperm_cell),_C)_anisogamy_of_non-motile_cells_(egg_cell_and_spermatia)..html" ;"title="egg_cell_and_sperm_cell.html" ;" ...

organisms. Two worms join

clitella The clitellum is a thickened glandular and non-segmented section of the body wall near the head in earthworms and leeches, that secretes a viscid sac in which eggs are stored. It is located near the anterior end of the body, between the fourteenth ...

, the large, lighter-colored bands that contain the worms' reproductive organs, and are only prominent during the reproduction process. The two worms exchange sperm. Both worms may secrete cocoons that contain an egg 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. ;Statistics: * From egg to sexual maturity is about 20 weeks. * Net reproduction of 0.8 eggs per adult per week occurs. * Egg cells are

oviposit The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...

ed in a cocoon. * One ''E. hortensis'' embryo per egg per cocoon occurs.

References

Lumbricidae Animals described in 1890 {{annelid-stub