Due to their lack of a noticeable head, it has led many people to wonder, do earthworms have a front and a back end?
In actual fact, the earthworm does have a front and a back end. Despite us not being able to see the difference between one end and the other with our naked eyes, there are ways to detect which end the earthworm’s mouth is and which end its anus is.
In that sense, human and earthworm bodies have a similar function system – weirdly enough.
Let’s explore in more detail how to tell which end is the front and back of an earthworm, as well as how this helps a worm get around.
How Do I Know Which End of An Earthworm Is Which?
Simply put, as Phylum Annelida, a worm’s body starts with its head, where it has a tiny mouth used only to consume nutrients.
The food is then passed through their esophagus before moving on.
An earthworm uses its skin to breathe oxygen.
And, instead of eyes, the earthworm uses what are called receptors in its’ skin to detect light in order to better locate itself.
However, it is not just the exterior of the worm that differs from the human body.
In fact, their organs and entire digestive system are very different from ours.
Instead of a human heart, the worm’s aortic arches pump blood through its circulatory system.
When it comes to the digestive system, the worm uses its gizzard to grind up its food before being digested.
Then, at the end of the worm’s body, there is a tiny hole from which it releases its worm castings (i.e. worm poop).
Finally, by contracting and releasing its circular muscles and by using its setae to grip the soil, the worm moves forward without needing limbs.
However, it can be very difficult to determine which segment is the front end of the worm without using a microscope to detect the different holes at each end of the worm’s body.
One easy way of locating the front of the worm is by finding the clitellum.
The clitellum is the light-coloured, swollen band that encircles part of the worm.
Whichever end has the smaller part next to the clitellum is the worm’s head.
Can Worms Move in Both Directions (Forwards and Backwards)?
As mentioned, the earthworm uses small bristles on the exterior of its skin to grip the soil as it contracts its longitudinal muscles and then releases them, thus moving forward.
However, it would be interesting to know whether they can repeat this kind of movement, but backwards.
As it happens, worms can, in fact, use the same system to move backwards. They will do so to avoid objects, predators, etc.
Therefore, if you see a worm and you successfully locate its front end but are unsure as to why it is the longer length of their body that appears to be guiding the shorter part, it is simply because they are moving backwards.
Summary
Despite their very different structure, yes, they do have a front and a back end.
Earthworms have impressive bodies that have led to their survival for centuries.
Their bodies have perfectly adapted to their environments and, despite their small size, are incredibly impressive and fascinating. They have blood vessels, an intestine system, and more.
Despite their undeniable importance for life on this planet, it has taken literal centuries for people to start giving earthworms the respect that they deserve.
Even today, there are plenty of people who will only see earthworms as good bird food or fishing bait.
A simple explanation for this is that worms are not animals that are easy to relate to for us humans.
The earthworm’s body is something entirely different from what we know as a species.
So, next time you notice an earthworm wandering about, maybe you will take a moment to admire how the little creature is getting about.
You’ll also now be better equipped to figure out which end of a worm is the front and which end is the back.
Read other articles to find out more about worms like:
