In the eyes of other predators, earthworms are obviously an easy, low-defense meal, but you may not know how delicate the senses of earthworms are.
But you may have wondered, do worms have eyes or do worms have ears?
No, earthworms do not have eyes or ears but do have light receptor cells on their skin and can also sense vibrations from the soil surface and underground. While these are fairly primitive sensory systems, they work well for the earthworm to navigate its environment.
Although there is no hard, outer shell for protection, an earthworm’s skin, light receptors, circular and longitudinal muscles and senses work well to help them survive.
In addition to having an amazing reproduction speed (see how do worms reproduce in our guide), below we will explain how earthworms use a variety of senses and characteristics to help them escape from death’s door and journey through life.
Where Are the Eyes or Ears of The Earthworm?
Earthworms are afraid of, and can sense light, but have no eyes (apart from the odd, rare species)
Because worms live and grow in dark and humid soil, the eyes do not play a role for most worms, so they have not evolved to need them.
However, other sensory organs of earthworms are very sensitive, such as the worm’s skin with light-sensitive cells called receptors.
If you have raised earthworms, you know that if you grab them out of the soil and put them into sunlight, they’ll try and burrow right back into the soil within a few seconds.
Because of this, many farmers still use the artificial light method in the video below to separate earthworms from their eggs or castings (feces).
Here I have shared a few methods for separating earthworms, earthworm eggs, and worm feces.
Do Earthworms Have Ears?
Earthworms have no ears, so they can’t hear sounds. But again, a worm’s skin comes in handy here too.
A worm’s body can sense sound produced by vibrations in their environment.
Whether it is walking, talking, or digging, there will be vibrations, and the earthworms will perceive them and escape in advance.
The earthworm’s body also has fine bristles that are barely visible that help them move even though a worm doesn’t have bones.
These bristles are mainly to assist movement and grip surfaces by increasing friction to aid their travel on smooth surfaces.
But they can also help earthworms to better perceive the subtle vibrations around the soil.
Some people historically also thought that worms could make sounds or noises, even scream or “call” at night but this isn’t true.
How Earthworms Use Their Senses to Escape
To see how they use vibrations to escape, let’s use the example of moles.
Moles love to burrow and are also the number one natural predator of earthworms.
Vibrations occur when the mole is digging a hole into the soil, so the earthworm will immediately begin to make an escape or even attempt to get out of the earth before it becomes lunch.
This isn’t always helpful for the worm, though, as other predators have caught on to their tactic..like birds and even humans!
In some countries, a type of vibration called worm grunting, is used by people to catch earthworms in the wild.
See the video below:
A clever example of an earthworm predator using worms sensitivity to vibrations against themselves, is the herring gull.
A European herring gull, likes to use its feet to stomp on the ground constantly to produce vibrations, forcing earthworms to crawl out of the soil, only for the worm to become lunch for the clever bird.
Earthworms Have a High Degree of Tactile, Chemical and Thermal Sensitivity
Let’s get a bit more “sciencey”.
The earthworm body is covered with what is known as epidermal sensor cells, epidermal receptors, and each cell contains thousands of hair-like sensors that transmit messages to nerve fibres.
This means the earthworm has a high degree of perception to stimuli in its surroundings such as perception to touch, chemicals, and temperature changes.
Then there is another sensory cell located in the mouth called the “buccal” receptor.
These cells also allow earthworms to have a developed sense of taste and smell.
Finally, the photoreceptor cells that detect light are mostly located on the dorsal surface (the top) of the worm, and they get fewer under the abdomen and the closer you get to the tail.
So, now you know how earthworms sense light and vibrations. Though they do not have eyes or ears, their other organs on their bodies more than make up for it.
Especially the largest organ on their body; their skin.
It’s how earthworms breathe through their skin in wet soil and acts as their lungs (but do worms have lungs? Check our guide).
It also has mucus on the suface to allow oxygen and carbon dioxide diffusion in and out of their blood.
Who needs eyes and ears when your whole body has the ability to do it all?
See our guides above, where we discuss the mouth of worms and how they eat.
https://pubmed.ncbi.nlm.nih.gov/34308994/ – Have the eyes of bioluminescent scale worms adapted to see their own light? A comparative study of eyes and vision in Harmothoe imbricata and Lepidonotus squamatus