A Note on Experimental Gigantic Eisenia and Dendrobaena Earthworms

Authors: Domínguez J* and Guimaraěs A

DOI: 10.23880/izab-16000515

Volume 6, Issue 5

Abstract

Earthworms are iteroparous organisms with indeterminate growth, i.e. they continue to increase in size throughout their life and after completion of sexual development. Terrestrial oligochaetes vary greatly in size. Depending on the species, adult earthworms can reach between 10 mm and 3 m in length and between <1 mm and >25 mm in width, with most being of length 5-15 cm. Among the more than 7000 species described to date, very few (~20) reach lengths greater than 1 m. The longest earthworm on record is Amynthas mekongianus, which is found in the mud banks of the Mekong River in Southeast Asia and which reaches almost 3 m in length. It is about the same size as Megascolides australis, the ‘Giant Gippsland Earthworm’. These atypically giant earthworm species remain a scientific curiosity in terms of their biology, but they cannot be considered cases of gigantism. Gigantism occurs when organisms are much larger than normal or exhibit excessive growth. The biology, life cycle and growth and reproduction rates of Eisenia fetida (Savigny 1826) and Eisenia andrei (Bouché 1972), the earthworm species most commonly used in vermicomposting and vermiculture, have been widely reported. Here we present details of the enormous growth of individual specimens of Eisenia andrei and Dendrobaena hortensis reared under particular culture conditions and fed a special diet. Individuals almost 20 times the average weight of individuals of the species have been obtained. Possible explanations for this interesting phenomenon are discussed.

Keywords: Gigantism; Earthworm Growth; Eisenia

View PDF