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Enchytraeidae is a vast family of microdrile oligochaeta, commonly referred to as potworms or white worms. This family is composed of terrestrial and marine species, of which generally appear similar to miniature earthworms. The common name derives from their proneness to be found within the soil of container plants [2]. Furthermore, many experienced gardeners are under the belief that soil or compost is not considered to be normal without the presence of potworms.

Close view of Enchytraeid worm (potworm).


Kingdom Phylum Class Order Family
Classification Animalia Annelida Clitellata Haplotaxida Enchytraeidae

This very common family consists of roughly 600 species across a wide range of genera, including:

  • Achaeta
  • Archienchytraeus
  • Cernosvitoviella
  • Christensenidrilus
  • Cognettia
  • Enchytraeina
  • Enchytraeus – includes a more well-known species, Enchytraeus buchholzi, commonly referred to as the grindal worm. They are commercially bred and sold as aquarium fish food.
  • Epitelphusa
  • Fridericia
  • Globulidrilus
  • Grania
  • Hemifridericia
  • Henlea
  • Lumbricillus
  • Marionina Parenchytraeus
  • Mesenchytraeus – includes several species that are commonly referred to as ice worms.
  • Neoenchytraeus
  • Randidrilus
  • Stephensoniella

Description and Characteristics

Cluster of white, terrestrial potworms.

Worms of the Enchytraeidae family are segmented relatives of the earthworm and are known for their anatomical resemblance. Species of potworms are much smaller than earthworms. However, enchytraeidae only reach an average of 10-20 mm in length at maturity [2]. Their bodies are visible to the naked eye, sometimes being mistaken for larvae of other worm species. Generally, most species of potworms are unpigmented or white in coloration. They are sometimes simply referred to as white worms, in their similar appearance to white threads upon the surface of the water and land. Although, certain species of glacial potworms- referred to as ice worms- often have bodies of darker brown or black shades [1].

Despite their small size, enchytraeids contribute significantly to soil porosity through their burrowing behaviors. Along with their larger relatives, potworms are constantly secreting mucus and producing casts within their burrows [3]. In addition, these small organisms are often observed in extremely high-density populations within the soil. Consequently, potworms heavily influence the bacterial and mineral content of the regions they inhabit.

Darker colored "ice worm".

Distribution and Habitats

Species of potworms are commonly found within moist soils of temperate regions, especially within compost piles and within the soil of potted plants [1]. Potworms are frequently observed living alongside earthworms; though within some colder regions, such as areas of the Netherlands, these small worms seem to replace earthworms and take-over the role of ecosystem engineer all together [3]. Often, enchytraeid will quickly develop into massive populations; numbering as many as 250,000 in a ten-square-foot area.

Most species of enchytraeidae prefer more acidic environments, though this common family inhabits a wide range of habitats. Enchytraeus buchholzi, an enchytraeid, survive and spend their entire life cycles within the harsh environments of glacial ice. Several species of potworms are also considered to be marine organisms and are found within a variety of aquatic ecosystems [2].


Potworms consume much of the same type of litter as earthworms. Most enchytraeids gain the majority of their nutrients from feeding upon fungal hyphae and bacterial material, along with excreta from other soil animals. They are efficient at aerating soil and decomposing organic materials. These worms are also commonly known to feed upon nematodes, while they are preyed upon by other larger soil organisms themselves [2]. In colder polar regions, glacial potworms are heavily reliant on ice algae as a food source [3].


[1] The Enchytraeids, or Pot Worms. (n.d.). https://www.chaosofdelight.org/enchytraeidae-1?msclkid=0ec7f802d0e211ec925a2572c9b3a7fa

[2] The Top Worm. Pot Worms: Classic Soil Inhabitants. (n.d.). https://www.allaboutworms.com/pot-worms-classic-soil-inhabitants?msclkid=ca1e3272d15e11ec9b32defd98ae37e8

[3] Wageningen University. Enchytraeids (Potworms). (n.d.). https://www.wur.nl/en/Research-Results/Chair-groups/Environmental-Sciences/Soil-Biology-Group/Research/The-Soil-Biota/Enchytraeids-potworms.htm