Do Earthworms Have a Mouth? How Worms Eat and Dig Through Soil

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I’ve talked about whether earthworms have eyes and ears before, so let’s talk about how earthworms eat and answer the question, do worms have a mouth? 

Usually, the shape of the earthworm is as sharp on both ends, and it is hard to see which end is the mouth and which is the anus. 

But, there’s a simple trick to tell the difference. You only need to pay attention to the position of the clitellum (sometimes known as the “saddle”) – the swollen part of the worm that circles its girth. The head of the worm is the side that’s closest to the clitellum.

Also, make a note of which direction the earthworm is moving in. This is especially handy in very young worms who have not yet developed the swollen clitellum. Worms will lead with their mouth side first.

Yes, earthworms have mouths and mouth muscles. They have something resembling a lip which extends over the mouth, but there are no teeth inside and it can be described more like a telescopic straw.

Though they are simple and underdeveloped in some ways, the mouths of earthworms are strong and muscular.

There is also a strong, muscular pharnyx inside an earthworm’s mouth. This is the part of the throat behind the mouth.

When their food is caught, it passes through the throat (and covered in saliva) and pushed down through the esophagus and stored in the crop (similar to how a cow’s stomach can store food).

When it is ready, it is then sent to the gizzard

After the food is ground down in the gizzard, it will be broken down, digested and absorbed through the intestines

The intestine of the earthworm accounts for about 2/3 of the body length. 

The undigested material will eventually be excreted from the anus and become what we call earthworm castings. 

These valuable earthworm feces are darker in color, have high nutritional value, and are easily absorbed by plants – see the effect of earthworm castings here.

The food earthworms eat are usually soft and rotten things such as dead leaves, vegetables and fruits, and animal manure. 

Most of these foods only need to be sucked into the body and then directly digested and absorbed through the stomach. But some foods cannot be eaten by earthworms.

The mouth of a worm is very powerful

Although it looks slow and simple, the mouth of an earthworm is actually very powerful. 

Even if the food is outside the entrance of the mouth, it can work almost as a vacuum to pull food into the vicinity of the mouth through the entrance. 

In addition to eating, the powerful mouth of earthworms can also help them penetrate into harder soil.

I also did an experiment with hard yellow clay before. The soil was bought at a nearby flower shop, because it was mixed with a lot of sand and stone, and even if it was put in water, it reamined quite hard.

Later, I put a few ANC African night worms on it, and after a while, they actually got in. 

To be honest, I was surprised. No wonder they can survive so many harsh environments.

Below are some photos of the experiment:

This is what I used to experiment with earthworm food. The darker brown pile in the middle is earthworm poo (because the earthworm moved from the other side and got some castings on its body). 

earthworms digging into clay with their mouth and earthworm castings

I found that when they are in relatively hard soil, sometimes they really can’t get in, so they have to move around on it until a relatively soft place is found and then slowly go down. 

In fact, as long as the pH, temperature, humidity and salinity are well controlled, earthworms are basically not too picky. You can buy some simple instruments for measurement or some pH strips.

Below, is an image showing my experiment with 3 mud piles of different humidity. All worms got in.

The first one, in hindsight was really too hard. When I dug them out, I was worried that it would break them.

worms burrowing into clay and sand

There are probably more than 30 in each pile, but only seven or eight didn’t manage to get in yet. There are only a few left around.

As a step further, I also tried to see if they could get in palm oil fibre, and they were able to adapt. 

In fact, when I went to open the palm oil bunches, some earthworms were also found in it. I was relieved to find that this might be a good earthworm feed.

Do you have any interesting stories or things you found out about a worms mouth that you didn’t know before? Tell us in the comments below.

Can earthworms get scared and escape? <– Find out here