Suitable worm species for vermicomposting

The Epigeic species earthworms have good potential for vermicomposting thanks to their natural abilities for processing organic wastes, their high speed of consumption, digestion and assimilation of organic matter, tolerance toward the environmental factors, short life-cycle and fast reproduction. These characteristics are typical just for some worm species and only five species in the world are used for vermicomposting. The most widely-spread and productive of these five species is Eisenia Fetida, also known as red Californian earthworm.


This is an earthworm, one of the 8 species of the Lümboritsid family of the Annelida phylum.

The different with these earthworms is their structure and their size.


They reach 60-130 mm in length and maximum width of 7.5 mm. The frontmost part of the head is broader, with stronger muscles and orange in colour. The rearmost part with the tail is narrower and weak. The mouth is positioned at the front of the head and the anus – at the end of the tail.

The number of segments can be as many as 80-110. The head segment is epolobic. The segments in the front part of the head are bigger and of deep red or orange-red colour. The spaces between the segments are without pigments and for that reason the tail looks vertebral. The pigmentation of the young earthworms is deeper.


There are chetae along the whole body of the earthworm which enable its movement. Each segment has 8 contiguous pairs of chetae and the distance between is them is aa=vs dd=1/2 of the worm measurement.


The adult earthworms have a thicker part between segments 24-32 which can be 7-9 segments in length and this is the place where a cocoon is formed. In the front part of the abdomen, between segments 9-12 there is an opening for male and female reproductive organs. The earthworms are hermaphrodites. The male C-shaped organs form one big cushion-like shape, and the female organs are located near the back.


The whole body of the earthworms is covered by epithelium which is a transparent mucous layer containing pores and cambium cells. This ensures smooth surface and slipperiness of the skin and enables the easy movement of the worm.



Reproduction of the red Californian earthworm 


Earthworms are monoecious (hermaphrodites) but in order to reproduce they must copulate with a mate. The earthworms reproduce only in special cocoons with eggs which they produce every 5-7 days when the conditions are most favorable.


The cocoons are elastic, with a lemon-like oval shape; the newly-formed cocoons are light- yellow in colour and after they mature, they get brown in colour. The cocoon is 2-4mm in diameter, and each cocoon contains 1-24 eggs. 


The newly-emerged earthworms are 4-7mm in length, they look like small threads and can be distinguished by their light red vertebrae.


After getting out of the cocoon, the small worms weigh 1 mg and they immediate start to feed; in 60 days they have reached 300-350 mg, within 9-10 weeks following their birth they have reached sexual maturity and within 5-6 months they have reach weight of 1-2 grams.


For the mature earthworms the cocoon-process in case of natural and favorable conditions during the summer lasts 2.5-3 months. Each worm can produce about 18-26 cocoons during that period from the beginning of May till the end of July. In case of most favorable conditions on the average 3 eggs from one cocoon have a chance to survive.


Locomotion of the red Californian earthworm 


The main part of the earthworm locomotory system is the strong muscular system around the body. The parapodia located onto the muscles secure the rhythmical contraction and relaxation of the body. These contraction and relaxation are transferred from parapodia to parapodia starting from the first to the last, i.e. to the end of the body. Thus, via these rhythmical movements, the worms move under the earth and build their tunnels.


The earthworms are of extreme importance for the uplift of soil layers. It has been proven that the concentration of worms is 100 earthworms per square meter for normal soils and these worms pass about 1000m throughout the summer season and uplift the soil layers, thus ensuring soil aeration. Meanwhile they eat the organic substances in the soil (plant and vegetable cells, soil bacteria, fungi etc) and enrich the soil with organic substances.


For one day the earthworms process soil with weight equal to their own weight by passing it through their digestive system and excreting it.



Feeding of the red Californian earthworm 


The earthworm body structure resembles two intertwined tubes. The outermost tube is the skin which surrounds the body and the inner tube is the digestive system. The space between them is filled with liquid.


The food enters through the earthworm’s mouth and is collected in the esophagus and the pharynx, and then passes in small portions to the grizzard. After being digested, the food passes through the intestines and is excreted through the anus. The wastes which are excreted through the anus following the digestion look like small pellets – casts.


The casts contain humic substances (humic acids and their salts) which regulate the structure of soil, improve its aeration and water-retaining properties, increase its mechanical stress resistance and soil fertility.


Furthermore, the casts act like a center for microbiological activity of the varied soil microflora, and the earthworms’ digestive system serves as a resource for constant renewal of generations of soil-dwelling microbes by increasing the carbon dioxide  and water and decomposing the dead animal and plant cells contained in the soil.


The soil is the main source of carbon dioxide in nature. The carbon dioxide emissions from the soil are absorbed by the green leaves and with the help of light energy (photosynthesis) are released to fuel the growing plant’s activities.


Without the carbon dioxide and the photosynthesis no form of life can begin, exist and develop on earth.


The earthworms and the biomes are the main living organisms which form the soil and the vegetation and ensure health and well-being for all living organisms.   

Gallery image