the essentials in brief
- Earthworms are beltworms and have almost 45 species in Germany. Their hidden life in the ground offers great benefits to gardeners. The inner and outer structures of the earth's inhabitants are adaptations to the habitat.
- The worms are hermaphrodites and need a partner to reproduce. Your eggs are laid in yellowish cocoons that are placed in the substrate. The development times depend on the type and the ambient temperatures.
- Each species belongs to one of three ecological groups, which describe the animals' habitat more precisely. Earthworms feed mainly on plant-based food and overwinter in caves they have dug themselves.
- The common one earthworm is the best known species in Germany and spread nationwide. Other groups of organisms have a limited range. Because of their high rate of reproduction, earthworms are easy to breed.
The earthworm in a profile
The compost worm (shown here) is slightly smaller and redder than the common earthworm
Earthworms represent a family within the belt worms. 46 species are currently known in Germany. The earthworm is called earthworm in English, whereby this name is used not only for the group of Lumbricidae but for all terrestrial worms.
also read
- What do earthworms do in the flower pot?
- Earthworms in the lawn
- Lure earthworms into the garden
One of the best-known species is the common earthworm (Lumbricus terrestris), which is nine to 30 centimeters long and is sometimes referred to as a dewworm. Another common species is the compost worm (Eisenia fetida), which is between six and 13 centimeters smaller.
Earthworms weigh an average of two grams. They become about one centimeter thick and develop a slimy protective covering to repel harmful substances and not dry them out.
Why earthworms are useful
When earthworms burrow through the soil, they mix the soil particles and ensure better oxygen circulation in the substrate pores. The digging activities ensure that nutrients get from the subsoil to the roots of the plants. The droppings also provide the plants with additional nutrients. By loosening the layers of the earth, rainwater can seep away better and compaction is prevented.
During the night, living beings transport fallen leaves from the surface of the earth into the underground duct system. This measure accelerates the rotting of the plant material. The helpers not only promote soil fertility, but also improve the living conditions for numerous soil organisms.
Internal and external anatomy
Earthworms are made up of numerous segments that are produced in the course of life by a special growth zone at the rear end. As a result, the length of a worm increases with age. When fully grown, the belt worms can produce up to 160 limbs. The anatomy and structure of the body are necessary adaptations to the living space.
Nervous system
Earthworms have a well-developed stimulus perception. In cross-section, the nerve tracts are reminiscent of a modified rope ladder nervous system. Paired nerve nodes, the so-called ganglia, are connected to one another by longitudinal and transverse struts. In earthworms, these components are combined into a nerve cord, which is known as the abdominal marrow. This main strand runs through the abdomen from the fourth segment to the tail.
Other structures of the nervous system:
- Brain (also called upper pharyngeal ganglion) in the third segment
- Sub-canal ganglion, which originates from the intestine
- three segmental nerves each branching off from the abdominal medulla in each limb
Digestive system
At the head end, the earthworm has a head flap that is arched over the mouth. This upper lip opens into a mouth opening with a direct connection to the intestine. It runs through the entire body and is subdivided into a muscular throat with esophagus as well as goiter and gizzard.
Earthworms are natural soil improvers because they reduce acidic soil substances through calcium-containing deposits.
The way it works is the same as with chickens. Grains of sand ingested with food grind them into pulp, which then runs through the long midgut and is excreted through the anus at the rear end.
How many hearts does an earthworm have?
Earthworms have five hearts
The invertebrates have five pairs of hearts that are in the seventh to eleventh segments. Their hearts are connected to each other and to the main blood vessels, so that a closed system is created. In this circulates red blood, which is pumped through the back vessel in the direction of the head and in the abdominal vessel in the back part. The blood circulation is of particular importance because it ensures the oxygen supply to the worms.
Useful information:
- every heart is muscular and highly contractile
- Skin needs to stay moist to allow oxygen uptake
- Earthworms can also breathe in oxygen-rich water
Earthworms have no olfactory organs. Breathing takes place predominantly through the skin. Further oxygen reaches the intestines through the food ingested and then into the bloodstream.
Does an earthworm have eyes?
The belt worms have no eyes, but can differentiate between light and dark. This perception is made possible by light sensory cells, which are located in the epidermis at the front and rear ends. With special tactile and gravity senses, earthworms orient themselves in the darkness of the ground. They perceive gaps or obstacles and know where up and down is. With the help of pressure senses, the invertebrates feel ground shocks so that they can flee from approaching predators in good time.
Locomotion
On the outside of each segment are four pairs of bristles made up of chitin and proteins. Circular and elongated muscles allow these appendages to move passively so that the worm can crawl back and forth. The direction of movement is influenced by the position of the hair structures.
Movement sequences when crawling:
- The bristles point backwards
- anterior sphincters contract
- Front end becomes thinner and longer
- rear segments are anchored in the ground by bristles
- Front part pushes towards the head
- Contraction of the longitudinal muscles backwards
- The rear end is pulled behind
Muscle contractions run faster in dangerous situations. These arise, for example, when touched or come about through light stimuli. The worm tries to escape in an escape response.
From the sexual act to the young worm
The reproduction of earthworms is a spectacular act in which both partners act as males. The female part only acts later, when the egg cocoons are produced. It can take different amounts of time until a young worm has developed from the egg.
Genital organs
Earthworms are hermaphrodites
Earthworms are not of a specific gender. They are hermaphrodites and have both male and female sexual organs. Some earthworm species fertilize themselves, although they generally prefer sexual reproduction with a partner. You can recognize sexually mature animals by their yellowish thickening.
This belt, known as the clitellum, develops between the ages of one and two years. It has a minimum of four and a maximum of 32 members and is between the ages of 17 and 17. and 52. Segment. The so-called puberty ridges, which form the side edges of the belt, are particularly noticeable.
When earthworms multiply:
- no fixed times for mating
- usual breeding season between early summer and autumn
- especially from May to June
- with favorable temperature and humidity conditions in the soil
Earthworm reproduction
The girdle has glands that produce a secretion before copulation. This is used so that the sexual partners can attach themselves to each other. Then both worms secrete a portion of sperm, which is transported to the clitellum by skin movements and then stored in the partner's semen pouches. The sperm are stored here for a few days before they fertilize the egg cells.
Digression
How often do earthworms multiply?
Egg laying
The earthworm produces a clitellum secretion, which later solidifies and forms the parchment-like shell of the egg cocoon. He fills this protective coat with a protein-containing liquid. The animal then pulls backwards out of the cocoon ring and releases several eggs and sperm into it. Fertilization takes place outside the body in the egg. After passing the head end, the capsule closes at the ends. The cocoons of earthworms are reminiscent of yellowish to brownish fertilizer pellets.
This is how earthworms lay their eggs:
- in the upper layers of the soil
- often a protective cover is also produced from feces
- like in compost
development
The protein in the cocoon serves as the first nourishment for the embryos before they undergo the metamorphosis into a transparent worm. It takes between 16 and 90 days for a fully developed baby to hatch, depending on the species and the outside temperature. The embryos of dungworms develop into young worms within around two weeks at around 25 degrees. Thawworms need three months, with low temperatures at around twelve degrees in the soil being sufficient.
Recognize young worms:
- are significantly smaller than adult earthworms
- Pigmentation is very weak
- Genital apparatus not yet available
Youtube
About the life of earthworms
Earthworms are adapted to a hidden existence. They only come to the surface after heavy rainfall, or they show up when digging up garden beds and compost heaps. Life on earth is full of dangers.
habitat
The earthworm lives mainly in the earth. The pigmentation depends on the microhabitat that colonizes the respective species. Worms that barely come to the surface of the soil are pale and lack pigment. On the other hand, those species that are observed more often on earth develop UV protection in the form of dark pigmentation.
A Earthworm in a flower pot did not immigrate from outside. It probably comes from an egg cocoon that is used in the forest or Compost soil found. The terrestrial animals can survive for a few days in water-saturated soils. Boggy subsoil is not populated.
building
When buried, earthworms leave far-reaching systems of ducts in the ground. You pull the circular muscles of the front segments together and drill a hole in the earth with the thin front part. By using the longitudinal muscles, this becomes thicker and pushes the earth particles apart.
Impressive facts:
- Corridors can be up to 20 meters long in one square meter
- Earthworms are among the most powerful animals in the world
- lift 50 to 60 times their own body weight when digging
Life expectancy
Earthworms live an average of two years
In nature, earthworms reach an average age of two years. Here their chance of survival is influenced by environmental conditions and enemies. The defenseless creatures are easy prey, which is why the number of predators is large. Many birds feed on the protein-rich soil organisms. Hedgehogs, moles, but also insects and amphibians are also predators. Some specimens lived to be ten years old under controlled conditions in the laboratory.
wintering
In unfavorable weather conditions, the worms seek protection in self-made caves under the earth, which are filled with the body's own secretions. As cold-blooded animals, they become frozen in winter because their body temperature adapts to the ambient temperature. Prolonged cold spells lead to enormous weight loss. After the cold season, the worms have lost around half of their body mass, so they have to go for extensive food in spring.
nourishment
The belt worms have a very well developed sense of taste. You perceive different aromas with the help of sensory buds in the oral cavity. This has an impact on the preferred food. They fill their intestines through their mouths with humus-rich soil and rotting plant material.
Tips
Place a humus box in the substrate between heavy-eating plants in the vegetable patch. Here you can collect biological waste, which is directly decomposed by worms. Your vegetables are constantly supplied with nutrients.
Occasionally they pull seedlings and leaves under the ground at night so that the plant material rots. To do this, they inflate their front end and press their mouths against a leaf. A kind of suction disk holds the material in place so that the worm can crawl backwards and transport it into the ground. Earthworms also absorb soil particles and break down the bacteria, fungal spores and protozoa that live on them.
Species richness among the earthworms
The common earthworm, along with the small fieldworm, is one of the most common species in Germany, the do not belong to the same genus and are assigned to two different ecological groups will:
- endogean earthworms: live in horizontal corridors that run through the upper mineral layer
- anectic earthworms: penetrate through vertical corridors to a depth of three meters
- epigeic earthworms: colonize organic layer on the ground
The compost worm belongs to the group of epigeic worms, while the anectic dewworm penetrates deeper soil layers. A large part of all genus occurring in Germany represents the endogean class. The small field worm is one of them.
| scientific name | colloquial | habitat | particularities | coloring | |
|---|---|---|---|---|---|
| Common earthworm | Lumbricus terrestris | Dewworm, eelworm | Meadows, gardens and orchards | only comes to the surface when there is dew | reddish in front, pale behind |
| Compost worm | Eisenia foetida | Stinkworm, Tennessey wiggler | Soils with a high proportion of organic material | Species is bred on worm farms | reddish with light to yellow rings |
| Small field worm | Allolobophora chlorotica | Garden worm | in heavy moist soils | lives in the upper mineral layer | pale bluish to greenish or pink |
| Red forest earthworm | Lumbricus rubellus | Red worm, red leaf eater | Soils rich in humus, old tree stumps | lives on earth under leaves | solid red |
| Big worm | Octolasion lacteum | – | in almost all soils | eats microorganisms on sand particles | milky blue to yellowish |
Species distribution in Germany
The biodiversity increases significantly towards the south, which can be traced back to the ice age processes. As a result of the glaciation in the north, numerous species became extinct or were displaced to the ice-free zones to the south. After the ice melted, only a few species were able to migrate to northern areas. Earthworm species that are comparatively widespread live here today. In contrast, a large number of earthworms are observed in the south, which have only a limited range.
Breeding earthworms
Earthworms are easy to breed
Many belt worms are easy to breed in captivity due to their low demands on environmental conditions and a high rate of reproduction. So-called worm farms are used for commercial use. In the private environment, the animals can be kept in worm boxes or an observation box.
Feed animals
In pet shops, worms of various types are offered as fishing bait or for feeding to reptiles and amphibians. Some specialized companies offer grow kits and accessories on the Internet. Breeding animals can be acquired fully grown or in the form of egg capsules. Since earthworms are hermaphroditic, you don't need to be gender sensitive.
How to pull worms from egg cocoons:
- Fill the worm box with soil, damp cardboard, newspaper or crushed coffee filters
- Place egg cocoons in the substrate
- Place the worm composter in a dark and warm place for four weeks
Soil improvement
Species with high conversion and reproduction rates are suitable for use in the garden to improve soil quality. The compost worm, which can also be grown in a worm box, is recommended for this area of application. After hatching, it is advisable to relocate it directly to the compost heap so that the young can find sufficient food. A worm composter is ideal for balconies and patios to breed worms.
Tips
Recently, tropical species have been offered to improve the soil. However, because of the neozoa problem, these are only recommended for use in closed systems such as greenhouses.
Digression
Bizarre from the earthworm cosmos
frequently asked Questions
What is an earthworm?
Earthworms are arthropods
The articulated living beings belong to the order of the few bristles, as each segment has bristles for crawling. They are not insects, even if they belong to the arthropods like crabs, spiders and beetles. Their slimy body consists of longitudinal and circular muscles that are used for locomotion or for digging caves.
How old does an earthworm get?
In general, the life expectancy of soil organisms is ten to twelve years. In nature, hardly any individual reaches this age, as the defenseless animals have many enemies and often fall victim to the environmental conditions. On average, the worms live to be two years old in the wild. They reach sexual maturity after about a year.
Can you divide an earthworm?
The soil organisms have an extraordinary ability to regenerate and can almost completely renew their rear end after separation. Each limb has the genetic make-up to form an anus. However, the head cannot be restored. It is a rumor that a worm can become two individuals through separation. Occasionally a severed posterior end forms segments with a second anus. Such an individual dies of starvation after a short time.
The front end has a chance of survival if it is after age 40. Segment was separated and thus has the vital lateral heart. Because wounds often become infected in the wild, the survival rate of fragmented earthworms is low.
What does an earthworm eat?
The invertebrates are omnivores that feed on biological waste and sometimes carrion. They use the food available near the entrance to their living areas. In addition to dead plant parts, their diet also includes microorganisms that live on rock particles. Through their activities as boring diggers, they accelerate the natural decomposition processes.
What do earthworms in the ground indicate?
Earthworms serve as bio-indicators and can point to heavy metal contamination of the soil. They absorb soil particles with mineral components and thereby accumulate metallic substances in the body. In the short term, the worms are not harmed by the accumulation in the organism. Due to their comparatively long lifespan, lumbricides can show environmental pollution added up over several years. The very existence of such species at a location allows certain conclusions to be drawn about soil pollution.
Can you eat earthworms?
Earthworms are increasingly found to be eaten. Due to the problem of parasitic organisms, this survival food should be avoided. Earthworms live symbiotically with bacteria, flagellates and ciliates. In addition, their body cavity is often infested with roundworms. Some of these types are Carrier lungworm diseases in poultry and pigs. Occasionally the gold fly lays its eggs in earthworms, so that the hatching larvae find optimal feeding conditions and eat the worm from within during their development.
