What’s Inside an Earthworm?

Earthworms are fascinating creatures that can regenerate parts of their bodies and are efficient muscular machines.

Earthworms are fascinating creatures that can regenerate parts of their bodies and are efficient muscular machines. These creatures are long and tubular, with a very simplistic brain. They also have no other defining facial features like eyes, ears, or nose. 

They’re common just about everywhere in the world, and if you go out after a rainstorm, there’s a great chance that you’ll see tons of earthworms wriggling around.


An earthworm’s mouth is dominated by a pharynx or a kind of tongue that juts out of the mouth and pulls food back in. Once the food is inside of the earthworm, it starts to decompose within the first few rungs of its body. Earthworms are vegetarian, and as the name suggests, they love to burrow in and eat dirt. They derive nutrients from different things that are commonly found inside of the soil, such as roots and leaves.

Gizzard Muscles

Unlike humans and other creatures, including insects, earthworms don’t actually have teeth. Instead, they sift through and crush up parts of the soil using their powerful gizzard muscles. When you consider the fact that earthworms are basically one long ring of muscles, you can appreciate how this process is done. 

After the gizzard muscles do their work minimizing the dirt, the earthworm’s intestines jump into action. The earthworm’s intestines actually break up food by digesting it chemically. This gives the earthworm the nutrition that it needs. 


Another thing that makes earthworms so remarkable is the fact that they have five hearts. Most animals, including humans, only have one heart, but the sheer length of the earthworm’s body and the process that it uses to digest food means that it needs five unique hearts to shift blood around in the body.

Earthworms also have a significant number of blood vessels, known as the ventral and dorsal blood vessels. These blood vessels connect the hearts and run all along the length of the earthworm. It’s a very sophisticated system overall.


The earthworm’s brain is also known as its cerebral ganglion, and it’s far less complex than a human brain or even the brains of comparable insects. The reason that the brain is primitive is that the rest of the earthworm’s functioning is so streamlined that it doesn’t need a powerful brain to give orders to it. 

Instead, the nervous system is a simple network of nerves and blood vessels that provide the earthworm cues as to what is around it. Remember, earthworms do not have eyes, so it relies on its brain and nervous system to tell it where there’s light, vibrations, sound, or danger.   


Earthworms have two distinct sets of muscles; longitudinal and circular muscles. These muscles comprise the meaty inside of the earthworm and help it inch around and furrow for nutrients in the dirt. The circular muscles allow the earthworm to contract in width, and they can become thinner and longer to squeeze into tight places or escape from predators. The circular muscles give earthworms most of their versatility.

Longitudinal muscles are ones that run all of the way down the earthworm instead of around its body like circular muscles. Like circular muscles, earthworms can change their shape by contracting the longitudinal muscles. They can be shorter and fatter rather than longer and skinnier. 

Ultimately, this gives the earthworm a whole range of movement and allows the simple creature to evade problems and predators.

Although earthworms are simple creatures, they are totally fascinating and, in some ways, more evolved than us. Every part of their bodies works alongside organs, muscles, and intestines to help them survive and forage for food.


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