An army of slugs can devour a newly sprouted vegetable garden. And can make a barefoot walk in the morning dew quite unpleasant. After fighting an excessive amount of slugs this past summer, I got to wondering: do slugs feel pain?
Here’s what I learned.
Can Slugs Feel Pain?
Yes, slugs can feel pain, but probably not in the same way that humans do. While slugs (Limax maximus) have a nervous system they lack some key components to feel pain as we do.
The evidence is clear that slugs react to outside stressors, like salt, heat, electricity, even human touch.
Slugs and Pain: Study
There are limited studies regarding the question of slugs and pain.
More than 12 years ago, there was a study that put a snail on a hot plate set to 100.4ºF (38ºC).
As you might expect, it reacted. First, it retracted into its shell. Then, it secreted thick mucus and began to search for a cooler environment.
This study establishes that slugs sense danger and take steps to protect themselves from it.
Do Slugs Have Brains?
Slugs have brains. Their neurons (brain nerve cells) are surprisingly large (200 to 300 microns in diameter). That means that slug neurons are visible without a microscope.
This is in contrast with the brain cells of more intelligent life forms that can’t be seen with the naked eye.
“A slug does have the sensory system necessary for responding to a change in its environment, which is why it curls up if you touch it. But it doesn’t have a cerebral cortex – that’s the part of the brain responsible for the conscious perception of pain.” Dr. Eric Chudler, Department of Anaesthesiology, University of Washington.
This is an important fact: without a cerebral cortex, slugs aren’t able to consciously perceive pain.
Pain is a feeling that the brain generates. It comes from the periaqueductal gray (PAG) and nucleus raphe magnus regions. Without these brain regions, it is unlikely that slugs actually feel pain.
Does Salt Hurt Slugs?
Salt kills slugs by dehydrating their moist bodies. While it happens quite quickly, it isn’t instantaneous.
Here’s why salt kills slugs.
Do Slugs Feel Pain from Salt?
The jury is out on slugs feeling pain from salt. We can reason on it, based on how slugs respond to the salt.
Likely, slugs can feel the discomfort of the salt and their impending doom. But thanks to their limited nervous system, they may not be able to process, and actually experience, the pain caused by the salt.
Is it cruel to kill slugs with salt? This is a personal question.
Here are some factors to consider.
- Most pest control methods involve some level of discomfort for the animal or insect.
- Almost pest controls have the single purpose of killing the insect or rodent. Very few are made as repellents.
- If you don’t kill the slug, will you be able to harvest your garden?
How to Get Rid of Slugs
While my preferred method of slug removal amounts to the pick-and-toss, many gardening blogs recommend salt or drowning these gelatinous blobs.
Others recommend using copper tape or wire to keep them from reaching their target.
If only the Slugbot actually went into production. This slug-picking, GPS-controlled robot can pick up to 100 slugs per hour. And even power itself with the slugs it collects.
I’ll cover more slug removal methods in a future post.
More reading: Guide to 5 Types of Banana Spiders
What is your opinion? Do you think slugs can feel pain? How will you handle slug removal next season? I think I’ll use a combination of throwing slugs (physical removal) and copper tape (physical barrier) instead of salting them.
- About the Author
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Bryan Haines is a co-founder and writer at The Buginator. And is working to make it the best resource for taking back the outdoors from biting, stinging pests.
He also blogs about travel at Storyteller.Travel and photography at Click Like This. Bryan is a partner at Storyteller Media, a publishing company he runs with his wife, Dena.