Do you know what happens to earthworms during their lifetime? Most people don’t. Earthworms go through a fascinating life cycle that starts with them laying cocoons, to hatching into little wormlings, to becoming juveniles and finally adults. In this blog post, we will take a closer look at the life cycle of earthworms and find out how they reproduce right under our feet in the soil below us.
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How Earthworms Reproduce
All most all earthworms have both male and female sex organs. The female sex organs consist of the ovaries, oviducts and spermathecae. The male sex organs consist of the testis sac, testes, seminal vesicles, spermiducal funnels, vasa deferentia, prostate glands and accessory glands. When two earthworms mate, in most cases, the male sex organ of one earthworm is intertwined with the female sex organs of the other (and vice versa) each earthworm will exchange sperm, resulting in both worms having eggs impregnated with the sperm of the other.
The thick band around the adult earthworm is called the Clitellum. In most species of earthworms, the clitellum moves backwards and the spermatozoa flow through the seminal groves to get into the partner’s spermathecae pores.
Development is direct in earthworms. Fertilization occurs within cocoons and one or more juveniles are produced for each cocoon.
The Lifecycle of The Earthworm
Earthworms: Cocoons to Hatchlings
The cocoon protects the eggs until they hatch into little wormlings. The number of eggs can vary based on species. Most contain 1 egg but some species can have as many as 20 eggs per cocoon. The hatching process takes about two weeks. Once the baby earthworms hatch, the hatchlings will start feeding on bacteria and organic matter right away. Hatchlings can look translucent to the human eye and are very easy to miss at this stage in the soil.
Earthworms: Hatchlings to Juveniles
It takes about two weeks for the baby earthworms to become juveniles. They start to grow larger and their skin starts to thicken. The juvenile stage is when the earthworms start to look more like adults, but they are not quite there yet. Juveniles are not yet sexually mature and don’t have the thick band (i.e. clitellum) close to their head.
Earthworms: Juveniles to Adults
The length of time it takes any earthworm to go from cocoon to adult can vary based on species, temperature, moisture and other environmental conditions. Most composting worms complete their life cycle in about 90 days. When an earthworm reaches adulthood, it has fully developed sex organs and is able to mate. The thick band around the adult’s body (clitellum) will secrete new cocoons, Starting the life cycle all over again.
How often do earthworms reproduce
Earthworms can mate any time of the year but they tend to reproduce more often during the warm months. The quality of where cocoons are deposited and the suitability of the burrows for their offsprings’ development are important factors. When the conditions are ideal earthworms will copulate more often. Some species of earthworms will build up a camber, of sorts and periodically clean it and surround it with fresh castings. These casts could be a means of maintaining the moisture content or protecting cocoons from preditors. The cocoons of earthworms are tiny- about 0.02 inches (0.50 millimetres) long.
Can an earthworm mate with itself?
Most earthworm species are hermaphrodites, meaning they have both male and female sex organs. Generally, earthworms are considered to be cross-fertilization hermaphrodites. Meaning the female sex organ of one earthworm interacts with the male sex organ o the other. However, cases of self-fertilization have been reported. In this instance, the earthworm would bend themselves allowing their spermathecal pores to contact the ventral zone of their clitellum. The sperm is then transported from their male pores to their spermathecae.
Do larger earthworms produce more worms?
Large earthworms have not been found to produce more cocoons, but they do tend to produce heavier cocoons and larger offspring. Earthworms tend to select partners of similar size. Most scientists have concluded that the primary purpose of mating is to fertilize the eggs of their partners, rather than to fertilize their own eggs.
How many hearts does an earthworm have?
An earthworm has five pairs of hearts. Four move blood through the body while the fifth pumps blood to the brain. The hearts are located in the front, centre and back of the body with two on each side.
What do earthworms eat?
The diet of an earthworm largely depends on the type of earthworm. Composting worms are scavengers and feed mostly on decaying organic matter such as leaves, fruits, vegetables and manure. Earthworms that live in the lower levels of the soil ingest soil to extract the organic matter and minerals they need to survive.
What does an earthworm excrete?
Earthworms don’t pee. However, they do excrete solids largely referred to as worm castings. Non-composting worms that live in the lower layers of the soil excrete a mixture of soil, mucus and undigested food through their anus. The mucus helps keep their skin moist and the soil helps maintain the correct pH balance in their bodies.
Do earthworms have brains?
Yes, earthworms have a brain that is located in the front part of their body. It controls many vital functions such as movement, digestion and reproduction. The brain is very small and does not have any eyes or ears.
What do earthworms feel?
Earthworms feel a variety of sensations such as touch, vibration, light, moisture and chemical stimuli. They can sense when they are being picked up and will often coil up in defence. Some scientists believe that earthworms are also able to feel pain.
Do earthworms sleep?
It is not clear if earthworms sleep. However, they do enter a state of dormancy called estivation during periods of extreme heat or drought. Estivation allows them to conserve energy and survive for long periods of time without food or water.
How long do earthworms live?
The average lifespan of an earthworm is about two to three years but some have been known to live up to six years.
Earthworms are an important part of the soil food web and play a vital role in our environment. By understanding their life cycle, we can appreciate their importance even more! If you want to learn more about earthworms, check out some of our other posts:
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