Classification of Earthworms

The earthworm has been mentioned in history as far back as Aristotle who dubbed the earthworm as "the intestines of the earth", and Cleopatra who had protective laws. Charles Darwin demonstrated that earthworms improve soil conditions and enhance plant productivity.

Scholars of the 18th Century devised a system of classification of plants and animals based on similarities of structure. They also established conventions for naming the classification units based on the Latin and Greek languages. The same basic system exists today and comprises the scientific discipline known as taxonomy, which has strict rules governed by an international body.

In 1758 Linnaeus proposed a system for naming all animal and plant species then known to science. The Linnaeun system is still followed today to provide scientific names.

The basic unit of zoological classification is the 'species', representing a group of animals which can interbreed and produce fertile offspring. All human races can interbreed, even though they have many and varied forms, sizes and colors, and are thus one species known as ....... sapiens. The species name always commences with a small letter.

The unit above (preceding) the species is the 'genus'. The genus always starts with a capital letter. It comprises a group of different species, all sharing a common set of characteristics: such as Homo ... ... thus Homo sapiens. These names are always underlined or italicized in text.

Above the genus is the 'Family', also commencing with a capital letter. There are other higher classifications, but these are the basic ones. The only other classification that you might need to know about is the 'sub-species', which is a classification where two species who have a further constant differing feature can be separated into a sub-species.

To give a practical example amongst worms, many common earthworms belong to the Family Lumbricidae. A common genus in this family is Lumbricus. There are several species of Lumbricus, such as terrestris, the classic 'text book' worm so well known in Europe and North America, and rubellus, which is the common 'red' found under dung in southern Australia. And so we have Lumbricus terrestris and Lumbricus rubellus.

Another well known worm which belongs to a different genus is Eisenia and a species name is fetida. And so the full name is Eisenia fetida, commonly called the 'tiger worm'. There is a uni-colored variant, the 'red tigerworm' which is called andrei. It is referred to as Eisenia andrei.

To complete the scientific description the name of the person who first made a scientific description of a particular species (the Author) is placed after the species name, together with the date on which the description was published. Thus our friend the 'uni-colored tigerworm' is then Eisenia andrei Bouche (1972). lt was Marcel Bouche who first described the variant as an acceptable species in 1972. Once the full name has been cited in the text, this can be abbreviated, e.g. E. andrei.

All very confusing? Why bother, you might ask, with sometimes unpronounceable Latin and Greek names. The answer is that the scientific names are used and understood worldwide, but 'common' or 'local' names often differ from country to country for the same animal or plant, or the same 'common' name is used to describe two different animals. Worm growers should be able to identify their species.