How do earthworms protect themselves despite seeming so harmless?
Earthworms are annelids, also known as Phylum Annelida, whose original habitat was, in fact, the ocean. Over time, they have evolved with bodies adept at surviving on and in the land.
The Earthworms we find in our gardens today have several means of defense to deal with predators. They also have some impressive extra sensory perceptions to detect impending danger.
They can adapt to different temperatures, protect their skin from injury whilst burrowing and even regenerate a body segment.
However, knowing that the earthworm’s body does not possess eyes, ears, or even a nose, how do worms protect themselves?
Worms have multiple ways of protecting themselves from other animals, dangerous environments, etc. Despite lacking general limbs and facial features that most other organisms use to survive, worms use the small bristles that line their skin, also known as receptors, to detect adequate environmental conditions, surrounding insects, other animal species, etc.
The ways earthworms protect themselves are:
- Emitting odors from their skin
- Emitting slime (coelomic fluid) and mucus from their skin
- By attaching their setae (bristles) to the soil to anchor themselves down
- Regeneration of their harmed segments (if the half of their body with their vital organs remains unharmed)
- Sensing vibrations and moving away from them
Let’s take a closer look at what these receptors are and how the earthworm uses them. How do earthworms protect themselves? You might be surprised.
Do Worms Have a Defense Mechanism?
Yes, earthworms have several defense mechanisms. Some are reactionary to external stimuli, and some are automatic.
The body of the earthworm is composed of segments and circular muscles that contract and relax in order for the worm to burrow in the soil.
A simple ever-present defence mechanism is the slime they excrete externally to protect their body, also known as coelomic fluid.
Earthworm bodies are tender. They also breathe through their skin, so it is essential that their environment is adequate for their breathing.
They move through some rugged material, and to protect their bodies, the mucus coats their segments and enables them to move more easily.
This is an automatic defence mechanism that makes their transit smoother and more comfortable.
However, in order for the earthworm to maintain that fluid and be able to breathe, they need to be in damp soil at all times.
If they sense that the ground is too dry, then they will burrow towards a damper and more adequate area.
On the other hand, should the worms feel too much moisture, in order to avoid drowning, they will also leave the area, thereby tunnelling their way away.
The tunnels aerate the soil, thus making a healthier ground for the growing plants, grass, and other vegetation.
How Do Worms Stay Safe from Predators?
Along the ring-like segments, there are hair-like fibres known as ‘setae’.
If a predator tries to pluck them from their path, earthworms can attach setae to soil and resist the predator.
Studies have shown the setae are so strong, the body of a worm can snap under the stress of being pulled before the setae break away.
However, before the earthworm is even found, it can detect predators from quite a bit away. Worms can detect vibrations which allow them to sense the presence of certain animal species such as moles.
The earthworm will therefore leave the ground and reach the surface of the soil in order to avoid its predator.
However, certain other creatures, such as birds, have understood this and will frequently tap the soil with their beaks to mimic the vibrations, thus bringing the worm to the surface to be eaten.
What Do Earthworms Do to Survive?
Earthworms possess a very impressive ability to regenerate part of their body. The vital organs of earthworms are contained in one half of their body.
Should they be caught by a predator, the worm may survive provided it is able to regenerate the part of the body containing no organs. If that piece is seriously damaged or bitten off, the wound may not be fatal.
The worm can regenerate that body part and eventually move along untroubled by the event.
Instinctively, earthworms also burrow deep in winter or in very hot weather to preserve their body temperature. Strong sunlight could be fatal by drying out their body.
Thankfully, finding the right environment for them is not as difficult as it may appear. For one thing, worms live off decaying organic matter.
This means that they can eat soil, plant roots, leaf litter, and all sorts of nutrients as long as the food presents itself as decaying organic matter.
Actually, they feed off of microscopic bacteria found in their food. In fact, these little creatures can eat up to half of their body weight every day.
Some worms also emit an unpleasant odour which can put off some potential predators.
Despite what we humans may think, not all earthworms are as helpless as they may seem.
Earthworms live and have lived on this earth for thousands and thousands of years, which they would not have been able to achieve had they not had any means of protecting themselves.
Although these invertebrates do have specific needs regarding their environment (moisture, light, oxygen, etc.), they are more than capable of using their abilities to find their best environment and thrive.