Why Do Tortoises Eat Rocks & Stones (Sometimes)?

If you’ve seen your tortoise snacking on some rocks, stones or pebbles, don’t worry, you’re not the first person to witness this behavior – it’s pretty standard stuff for tortoises. However, it is important that you know what to do if your tortoise is eating stones.

So why do tortoises eat rocks and stones? Tortoises sometimes eat rocks and stones to make up for a mineral deficiency in the their diets. It might be that they mistake rocks for actual food; other times they just want to explore and seek new stimuli.

Does it matter if tortoises eat rocks and stones? We think it does and that it might be a risk to their health. So, let’s find out why they do this and what you can do about it.

Why do tortoises eat rocks and stones? - TortoiseOwner.com
Why do tortoises eat rocks and stones? – TortoiseOwner.com

Why Tortoises May Eat Rocks And Stones

It’s not unusual for tortoises to snack on pebbles or stones. In fact, wild tortoises often use the consumption of rocks to offset specific deficiencies in their diets. However, given that the consumption of such items is not entirely risk-free (as we shall see a bit later in this article), it’s probably best to try and stop pet tortoises from doing this.

So, why is it that a tortoise might choose to eat something which, at first glance, appears so inedible? Well, there are three main reasons, let’s take a look at them:

They’ve Got A Mineral Deficiency

The most common reason for a tortoise to snack on rocks is because they feel that their body is missing a specific mineral and that they’ve identified that mineral in the rock. This is, actually, a fairly clever trick and if anybody thinks tortoises aren’t very clever, this is good proof that they’re much brighter than people think.

However, it is worth noting that rocks are not exactly easy to digest and that means your tortoise may not get enough of whatever it is they are deficient of from eating rocks and pebbles.

They’re Bored

A tortoise is a bright and curious animal and while they may never win a Nobel Prize for Physics, they need to live in an environment that engages their mind. If they find that they’re not getting enough stimuli, they may start acting strangely.

Related article: Do pet tortoises need toys?

One example of such strange behavior is when a tortoise starts to eat anything that they can get their paws on and force down. Fortunately, this is a very easy behavior to discourage, you give the tortoise more space and provide activities that keep them interested.

They’re Mistaking Them For Other Food

OK, tortoises are clever but they’re not that clever. Tortoises may just start snacking on rocks because they seem to smell of their food stuffs or because they bear some passing resemblance (in the tortoise’s mind) to actual food.

There’s not much you can do about this and, hopefully, it’s just a phase. Though if there’s a way to remove small pebbles from their environment, easily, you can always do that – tortoises can’t eat what they can’t reach.

Related article: Can tortoises get fat? (The problem with overfeeding)

The Minerals That A Tortoise Needs

As a living being, tortoises need a reasonable number of vitamins, minerals, etc. to keep them healthy. There are two minerals, in particular, which are essential to a tortoise’s ability to lead a happy life – calcium and phosphorous.

Related article: How to feed a tortoise: The guide to tortoise diet, food, & nutritional needs


Calcium is the most vital mineral to tortoises. It forms a large part of their body and in particular their skeleton and their shell. In order for a tortoise to grown and thrive they need a lot of dietary calcium.

For this calcium to be used effectively in the body, they also need a lot of Vitamin D3, fortunately, their bodies produce this vitamin naturally without any need for it in their diets as long as they get sunlight. This is the main reason that tortoises bask.

Calcium also helps in the operation of their nervous system and it helps regulate their heartbeat. It plays a role in blood clotting, muscle growth, the absorption of iron and many other bodily processes.

Despite all this, tortoises don’t digest calcium particularly well and it may be that they need supplementary calcium even if there is enough calcium present in their diet.


Phosphorous is the second most important mineral to a tortoise’s body and it works with calcium in most cases. Though it also helps to regulate the function of the kidneys.

However, tortoises absorb phosphorous very effectively and they must digest enough calcium in proportion to that phosphorous to live a healthy life. This means that you should never need to supplement phosphorous in a tortoise’s diet.

Trace Minerals

There are plenty of other minerals such as magnesium, sodium, sulfur, etc. found in a tortoise’s body in reasonable quantity all of these are easily found in an ordinary diet and do not need supplementing.

There are other “trace minerals” such as copper, iron, fluorine, etc. that are not needed in large quantities to ensure the tortoise’s health.

The only mineral other than calcium that a tortoise may need as a supplement is iodine.

The Need For Further Research

Sadly, while there is an assumption that reptiles will need a similar array of other minerals as mammals do, there’s been no in-depth research in this area. That means it’s going to be hard to detect a mineral deficiency (other than calcium or phosphorous) and it will make it hard to address it too.

It seems likely, given the growth in universities and research globally, that such research will be carried out eventually – but we’re not sure of when that might be.

Your best bet for a healthy and happy tortoise in the long-run, is a varied diet of proper food rich in leafy greens, flowers, and occasionally tiny pieces of fruit. Always consult your vet before feeding anything new to your pet tortoise.

Tortoise food supplement - TortoiseOwner.com
An occasional supplement is good as part of a diet rich in natural foods – foods tortoises would eat in the wild.

Should I Give My Tortoise Mineral Supplements?

You should only give a tortoise supplements if a vet recommends that you do. Indiscriminate use of supplements may actually cause harm to their health – they do not have similar needs for vitamins and minerals as people do and you should never give a tortoise a supplement intended for a human  being.

Related article: What to do if a tortoise vomits or pukes

How to give calcium supplements to your tortoise

The easiest way to give a tortoise calcium supplements is to give them crushed-cuttlefish in their diet or a calcium powder. You just dust these over their food.

It’s important to note because they find it challenging to digest calcium – it’s best to give this supplement at a different time from any other supplements or medicines that the tortoise may be given in their food.

Can Eating Rocks Be Dangerous To My Tortoise?

Yes, eating rocks can be dangerous to tortoises. While you shouldn’t panic when you see a tortoise snack on a rock, you should be concerned as there are two potentially serious health outcomes related to this habit.

Internal Issues

As you might expect, the biggest risk from eating rocks is that the rocks get trapped inside your tortoise. If the pebble doesn’t break down (at least a little) while travelling through your tortoise then it might get stuck inside somewhere.

In particular, there’s a chance of the pebble getting stuck in the tortoise’s intestines. If this happens, it may block the entire digestive tract. That’s bad news. If you’ve seen the tortoise eating rocks and then they start to refuse to eat at all – it’s time for a trip to the vet.

They may need to perform surgery on your tortoise to get the rock out too.

External Damage

This is a lower risk and only applies, generally speaking, to tortoise with softer shells and skin – they can get scratched up while moving on or around rocks and pebbles. While this might not sound too serious, reptiles don’t heal as well as mammals and their cuts can get infected easily.

It’s best to try and keep tortoises away from rocks and pebbles for this reason and you certainly shouldn’t add any rocks or pebbles to their environment whether you keep them indoors or outdoors.


We hope that our guide to “Why tortoises eat rocks and stones (sometimes)” has been helpful and that you understand why this behavior is both completely normal and something that you want to gently discourage for your pet tortoises.

If they aren’t getting enough minerals, you can give them supplements and if they’re bored, you can give them alternative stimuli. Keeping your tortoises safe from harm (even self-harm) isn’t as challenging as you might have thought.


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