10 Fascinating Facts About Slugs

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Slugs. An absolute menace in the vegetable garden. The swines will devour just about anything. None of our fruit or vegetable plants are safe. Controlling them naturally is a continual battle and you can find out how by checking out “How to Control Slugs Naturally“. Slugs are, however, pretty interesting little critters. Frustrating and intensely irritating, yes. But also interesting – and vital to the natural cycle, as they aid in rapid decomposition and return much-needed nutrients to the soil. Here are some fascinating facts about slugs.

slug eating

1 – Slugs Evolved From Snails

Snails have a kind of exoskeleton in the form of a shell and have the ability to retreat inside in the face of danger or when it’s too hot and dry. Slugs evolved without the shell, scientists believe, due to lack of calcium in the environment and high dampness or humidity levels. Not all signs of the shell have vanished among the majority of slug species, however. They have a vestigial shell in the form of a leathery mantle that sits on their back. The mantle consists of a soft but leathery outer layer, with a semi-hard calcium “shell” beneath.

2 – You Can Only See 5 Percent of Slugs

Think you’ve got a bad slug problem because you can see a few hundred slugs devouring your lettuces? Well, you’re only seeing around 5 percent of the problem. Only between 5 and 10 percent of slugs are above ground. The remaining 90 to 95 percent of the slug population is below ground. And that’s not accounting for all the eggs – that’s literally just the percentage of juvenile and adult slugs that are underground, chomping on seedlings and roots. Obviously, the slug population will vary according to where you live, but to give you some idea, studies show that the average garden in the UK plays host to around 20,000 slugs.

3 – Asexuality

Slugs have both male and female genitalia. If there are no suitable mates, slugs can impregnate themselves. So, when two slugs mate, both get pregnant as they exchange sperm. Slugs partially encircle one another, then their male genitalia appears from beneath their mantles. The male parts of the slugs join together in a kind of corkscrew to exchange sperm. However, they frequently get stuck like this. Then one slug will chew off the penis of its partner or even its own to get “unstuck”. The victim, however, can survive with just female genitalia and can continue to breed.

4 – 90,000 Descendants Each

A single slug lays up to 100 eggs several times each year. And bearing in mind that, mostly, when slugs mate, both get pregnant, you can see how quickly 1000s of slugs can appear. A single slug can accumulate a staggering 90,000 descendants during its lifetime.

5 – Just When You Think It’s Safe

Slug eggs are those tiny pearly white balls you find in the soil as you dig. Small, round, delicate, and easy to squish. But they are remarkably resilient. Slug eggs can lay dormant for years and only begin to hatch when conditions are optimal. So, even if you’re sure you’re totally on top of controlling slugs naturally, there can, in fact, be thousands of eggs in your soil, just waiting for the perfect conditions.

picture of a slug

6 – Stomach Foot

Slugs are gastropods. Which literally means stomach foot. The foot, which is the flat bottom side of the slug, is essentially a powerful muscle. This muscle contracts in rhythmic waves while the slug secretes the notorious slime at the same time. This allows the slug to glide across the slime as its foot contracts.

7 – Teeth!

Yes, slugs have teeth. 27,000 teeth to be precise. They use this ridiculous number of teeth to rasp away at their food, hence they leave such ragged holes in leaves. Who would think that a slug has more teeth than a shark? And, just like sharks, slugs regularly lose and replace teeth.

8 – Surprisingly Stretchy

Disturbingly, slugs can stretch to 20 times their standard length at will. That’s why it’s so difficult to keep slugs out of specific areas. They can stretch out and wriggle through tiny holes.

9 – Green Blood

If you start skewering slugs or decapitating them as a natural method of control, or, if you accidentally squish one under your boot, you’ll see that they exude green-yellowish blood. This is due to the molecule, hemocyanin, that transports oxygen in slugs.

10 – Multipurpose Slime

Slug slime is gross. But for the slug, it’s crucial. Firstly, it allows them to glide the foot muscle along the ground as described above. A slug’s slime is as unique as human fingerprints. That’s pretty amazing. They use this uniqueness to find their way to and from shelter, particularly tasty patches of vegetation, and more. The slime is also highly absorbent, so water simply makes it more effective, hence it’s so difficult to wash off your hands. Slime contains special fibers that make it extra sticky and helps to ensure slugs can make vertical climbs without sliding backward.

There are so many more weird, interesting, bizarre facts about slugs that we could’ve included here. But we think these are the ten most interesting ones. And the information here gives you a good foundation of knowledge. After all, as the old adage goes, know your enemy.

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2 thoughts on “10 Fascinating Facts About Slugs”

  1. Wow does this bring me back. When I was a kid slugs were everywhere! They were pretty much disgusting for me then and now (sorry!). I remember there were slugs so big and long and they were really slimey that you can see the slime from afar.

    1. Yeah, it’s undeniable – slugs are just disgusting. I mean, their scientific name even means “mouth foot” – ewww. They are kind of fascinating in a gross, disturbing kind of way – they stretch up to 20 times their length!

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