Enchytraeus (Enchytraeus albidus) are also occasionally referred to as “white worms” or bristle worms in the literature and – like earthworms – systematically belong to the phylum of annelids (Annelida). They are an excellent food for fish, reptiles, and amphibians.
Enchytraeus can grow up to 50 mm long, are relatively delicate skinned, white to yellowish in color and often more or less transparent. They usually reach an age of 2 – 9 months, sometimes longer. The development from egg to sexually mature animal takes about 5 – 7 weeks.
Great Species Richness
The white, yellow or transparent worms, which look like spaghetti at first glance, are found all over the world with over 650 species (except in Antarctica). In Central Europe between 200 and 300 species can be found. The long thin body can grow up to 3 cm long. The Enchyträen divide themselves again into several species. Not every species grows so long. When the enchytraeus are transparent, you can see their inside, that is their intestinal contents, because their blood is also transparent. The circulation of the blood is caused by the heart (contractile blood vessel). It pulls forward from the posterior girdle region to the dorsal upper girdle ganglion, where it pulls back again.
In adult enchytraeus, the first bristle-less segment (peristomium) is followed by up to 70 bristle segments. Each individual segment is provided with two dorsal and two ventral bristle bundles of two to six bristles. The girdle is found on bristle segments 12 and 13. Since enchytraeus are usually bisexual, i.e., hermaphrodites, it is easy to breed them. The male sexual opening is found on segment 12 and the female on segment 13. The seed pocket is located on the fifth segment.
Due to carry-over, the species are nowadays not so easy to separate from each other worldwide and the occurrence of the individual enchytraeus species is no longer restricted to individual areas or continents. In addition, the appearance of the species is usually so similar that they can only be distinguished from each other under a microscope by analyzing the sperm. The animals depend on moisture in their habitat, as this is what wets their skin. They are found in both salt water and fresh water, such as puddles, ponds, lakes and oceans, but also on the beach in moist sand.
However, most species do not live in water, but on wet land, that is, the habitat is terrestrial. Wherever the soil is moist enough and does not dry out, such as on meadows and fields or the compost heap, the worms find an ideal habitat up to 40 cm deep in the soil. The fewer earthworms there are in the soil, the more the enchytraeus worms multiply. This is especially the case with very acidic soils or heavy agricultural use.
The average population density is up to 100,000 specimens per square meter of earth surface. In some cases, as many as 290,000 specimens have been counted on just one square meter of moorland in England. However, such a mass and density in a very confined habitat only occurs with certain species. A much greater diversity of species, but with a lower density of occurrence, occurs in slightly acidic and also calcareous soils. Under good conditions in the habitat, enchytraeus live from 100 days to over a year.
Enchytraeus in Nature
In nature, they colonize the litter layer and the upper, humus-rich mineral soil. Their occurrence and distribution in the soil depend on the degree of soil moisture, the pH value, the food supply, and the respective competitive situation.
They feed on bacteria, fungi, dead organic matter, and enriched mineral soil. Enchytraeus cannot dig tunnels and are therefore dependent on loose soil.
The food intake of enchytraeus is saprophytic. Rotten plant remains are ingested together with the microflora (bacteria, protozoa, fungi) via the mouth pores. The protruding mouth is pressed onto food particles, which remain on it and are then drawn in. The end product is musty humus.
The Reproduction of the Enchytraeus
In order for us to breed enchytraeus properly, we must first understand how they reproduce. Enchytraeus are also called girdle worms, but this girdle, which is intended for reproduction, is only formed in fully developed, i.e. sexually mature worms. At this girdle is the penis bulb and the maturation of the eggs. Glandular cells on the girdle form the cocoon, i.e. the egg and the required cocoon fluid. In order for the girdle worm to reproduce, it places its body parts on top of each other, thus the fifth and twelfth segments lie on top of each other.
At this, the pressure of the coelomic fluid changes and the penis bulb is bulged out. As we learned earlier, most species are hermaphrodites, yet enchytraeus use a different sexual partner to reproduce. In this process, the bulb of the penis that is bulged out is placed in the opening of the partner’s spermatheca. The sperm is stored and fertilization occurs outside the body. After the reproductive act is over, the penile bulb is retracted by muscles. Enchytraeus are arranged bilaterally, meaning all reproductive organs are present in pairs in the same section.
In the next step the oviposition begins, for which you have to wait a few days. The girdle forms the cocoon sheath and brings in at least one, but usually several yolk-rich eggs. The girdle is now much thicker than in the normal state. Once the cocoon has been prepared and is ready for fertilization, the girdle worm crawls backward through the cocoon, which is constructed in a circular pattern, until the worm’s spermathecal opening is level with the cocoon. Only now can the sperm enter the cocoon. After this act, the girdle worm leaves the cocoon and it closes. This gives it the shape of a lemon. To prevent the fertilized cocoon from drying out, it is still covered with soil particles. Particularly fertile specimens release up to one cocoon per day.
The temperature must be as constant as possible at 21° C. Then the young enchytraeus larvae hatch after about nine days. Already eight days later the young girdle worms are sexually mature. After hatching, the small enchytraeus have only 17 to 21 segments. Until they are sexually mature, they grow. In other Enchytraeus species, such as Enchytraeus fragmentosus, reproduction takes place by division. Not only in breeding this species can be artificially reproduced by dividing, but also in nature this species disintegrates into several parts. After a few days new enchytraeus are formed again.
Keeping and breeding enchytraeus is relatively simple. It requires only regular control and a few simple foods. Breeding is done in containers (plastic containers, wooden boxes or similar) with a well-sealing but perforated lid, protected against vermin with fly screen.
These are filled to about 3/4 of the height with forest soil or a similar loose and artificial fertilizer-free soil (e.g.: special enchytraeus breeding soil or pure coconut fiber). Soil containing clay is not suitable. In the center of the container, leave depression for the food mash and put a cover disk over it. Feeding is done every 3-4 days.
It takes about 6 weeks for the first enchytraeus to become sexually mature and reproduce, but then it happens very quickly.
A good feed consists of vegetables and oatmeal. A mixture of cauliflower, carrots and potatoes, boiled until soft and mashed into a pulp, has worked very well. Add some salt (3 teaspoons per kilo of mixture) and oatmeal to make the mixture firmer. If needed, mineral supplements or fish food flakes can be mixed in to increase the nutritional value of the worms.
A notable advantage of enchytraeus is that they can be “inoculated” with active ingredients such as medications, vitamins, etc. through their diet, and these are then passed on to the fish through feeding.
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