Kingdom animalia
Phylum Annelid
Class Oligochaeta
Order Haplotaxide
Earthworms are animals with an elongated, cylindrical body, covered with rings and with some bristles, which help in locomotion. Currently, more than 4500 species are described, 300 in Brazil alone, and that can live both in fresh water and in a humid terrestrial environment. They come in different sizes and colors, depending on the species. Each individual can have an average of 1,500 descendants a year, and live for about five years.
They are predominantly nocturnal animals, staying buried during the day and leaving at night to feed and mate. They do not have an auditory or visual system, but some sensory cells are present, capturing mechanical, chemical, thermal and light stimuli.
Hermaphrodites, they reproduce sexually through exchanges of sperm between two individuals, in opposite directions, united by the ventral region; and asexually, by regeneration. Breathing is cutaneous.
The species found in terrestrial environment are the best known, mainly for digging tunnels, allowing better soil oxygenation and water retention; and act as a detritivorous organism, aiding the decomposition process of plant debris and other dead matter. In the latter case, it produces daily an amount of organic matter equivalent to its own weight, called humus, a natural fertilizer rich in nitrogen, calcium, magnesium, phosphorus and potassium.
In addition to the manufacture of this compound, earthworms are intended, economically speaking, to be used as fishing baits, for the manufacture of protein meals, cosmetics and medicines; in soil recovery, transformation of organic waste into products that are not harmful to the environment, and in food for humans and other animals.
Best known commercial species:
Eisenia foetida, popularly called the dung heap earthworm;
Lumbricus rubellus, known as the organic waste earthworm or California red earthworm;
Eudrilus eugeniae, the giant African earthworm.
Curiosity:
A species of earthworm, Lumbricus terrestris, is capable not only of making galleries in the ground, but also of traversing concrete structures; causing significant damage.
By Mariana Araguaia
Graduated in Biology