By Umar Mohammad
June 18, 2022
UPDATED 12:00 PM EST
[Photo credit: European Scientist]
Earthworms are one of the quintessential organisms we picture when we think of compost or simply soil. The Lumbricus terrestis (also referred to as angleworms) are decomposers, deriving all necessary supplementation from bacteria and fungi that grow on the decomposing matter. The invertebrates reside in all continents except Antarctica inhabiting almost every single type of soil in the world, pertaining to suitable humidity levels and organic content that satisfies their requirements. Their colors are dependent on their blood color. ‘Red wrigglers’ are red in color due to the pigment hemoglobin in their blood. Green worms are, well, green because they contain the pigment bilin. There is a total of 209 species in Europe and North America put together, with 30% of North American worms being non-native, and as such, imported.
Earthworms represent all terrestrial worms, belonging to the class Oligochaeta. They are categorized into three types: epigeic worms (the greek translation for ‘on the earth’), endogenic worms (below the ground), and anecic worms, which are a mix of the previous ones, living under the soil but venturing above ground for sustenance.
Epigeic worms are ‘catalysts’ for decomposition, residing amongst leaves, compost heaps, and generally, ain the topsoil later. In order to maintain high speeds (compared to its brethren), it has strong muscles They are darker in color to easily camouflage themselves from predators. Dark pigmentation also offers protection against UV rays.
Endogeic - translates from greek meaning ‘within the earth’- worms rarely venture beyond the topsoil, choosing to live in burrows beneath rocks. Said worms will venture to the surface during heavy rain to rehydrate themselves, burring vertically most of the time. When compared to their epigeic cousins, they are much slower due to weaker muscles, aerating the soil which agitates minerals whilst they eat the soil itself. Due to their endo-environment, they have a player, translucent complexion.
Anecic [‘out of the earth’] worms burrow vertically deep down, collecting their food from the surface and dragging them back down to the depths. They are the slowest type of worms, with weaker muscles compared to epigeic worms. They vary greatly in size.
References “Earthworms | NRCS Soils.” 2022. Usda.gov. 2022. https://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/soils/health/biology/?cid=nrcs142p2_053863
“WATCH: The Largest Earthworm Discovered in UK.” 2016. Animals. 2016. https://www.nationalgeographic.com/animals/invertebrates/facts/common-earthworm
“Macroinvertebrate | Animal | Britannica.” 2022. In Encyclopædia Britannica. https://www.britannica.com/animal/macroinvertebrate.
“Different Types of Earthworms with Pictures & Facts - Trees.com.” 2020. Trees.com. June 13, 2020.https://www.trees.com/gardening-and-landscaping/types-of-earthworms#Types-of-Earthworms