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Do Hermit Crabs Stink? (7 Causes of a Foul Odor)

Do Hermit Crabs Stink? (7 Causes of a Foul Odor)

The purpose of this blog is to share general information and is written to the author's best knowledge. It is not intended to be used in place of veterinary advice. For health concerns, please seek proper veterinary care.

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According to Allied Market Research, the air freshener market is expected to grow up to about $13.3 billion in the next few years, with the pet odor control market rising to about $3.94 billion.

Based on that, it’s clear to state that the demand for fresh and nice smelling households is on the rise, especially if we have pets. This is because many pets can easily start to produce foul odors within a short period of time for a lot of reasons.

If you’re into exotic aquatic animals, one of the most unique ones to have is the hermit crab. These bottom-dwelling scavengers with their unique shells can be an excellent display. But do hermit crabs stink?

In today’s article, we’ll take a deep dive into the world of hermit crabs and whether they produce a foul odor as well as the possible reasons for them to do so. Let’s jump right in!

What Does a Hermit Crab Smell Like?

Like most aquatic creatures, and especially crustaceans, hermit crabs have a distinctive smell. While this smell is not particularly pleasant, a lot of people may not have a problem with it. However, if you’re not able to tolerate the smell, hermit crabs simply aren’t the best pet for you.

Hermit crabs generally have a slightly fishy smell that some may describe as rotten. The happier and cleaner the crab, the less annoying this smell would be.

Similarly, the aquarium generally smells like the beach because of the mix of water and substrate. Similar to the crabs, the more frequently the habitat is cleaned up, the less potent its smell is going to be.

Do Hermit Crabs Smell Bad?

Regardless of the natural scent of crustaceans that hermit crabs emit, they can also produce a much more potent and borderline intolerable smell in some situations when conditions aren’t optimal for them.

In addition to the hermit crab itself, their habitat can also be the source of the smell, which can happen due to a variety of reasons. For example, the aquarium is neglected and not cleaned up regularly.

To sum things up, crabs do have a smell that doesn’t specifically stink, but the smell can be much stronger in some situations that we’ll tackle in the following sections.

Can Hermit Crabs Detect Their Smell?

Anatomically speaking, hermit crabs don’t have a nose that they use to smell. Despite that, they have an astonishingly good sense of smell.

Instead of noses, hermit crabs depend on their antennae to detect smells, which are embedded with hundreds or even thousands of small odor sensors.

According to a 2016 study, hermit crabs are able to detect various odors when the chemicals suspended in the air come in contact with their sensors. In fact, this is how hermit crabs find their food while scavenging.

This means that hermit crabs are able to also smell their predators and will be further distressed if they smell a foul odor, which worsens their case.

For that reason, it’s important that you keep the crabs clean to prevent them from smelling or being distressed due to the unclean habitat they’re in.

7 Reasons for the Foul Odor of the Hermit Crabs

As previously mentioned, a hermit crab has a distinct but not necessarily stinky smell. However, if the crab starts to stink, there are several reasons why this might happen. Let’s have a quick look at some of those reasons:

1 – Stress and Overstimulation

One of the main reasons why hermit crabs may produce a foul odor is being stressed out. This is because hermit crabs produce certain pheromones when they feel distressed, which have a particularly strong odor.

Additionally, when the crab is stressed, they can also lose a limb, and while they’re able to grow another one instead, the discarded one will end up rotting and releasing a foul smell.

This is one of the main reasons why hermit crabs are remarkably smelly when they’re introduced to their new homes, as they need some time to adapt to life in captivity.

You can even tell when the hermit crab is stressed, as they’ll start seeking out hiding spots, such as burrows.

However, if the crab has been adjusted a long time ago and it started to smell, lookout for some of the factors that may trigger their stress, which includes any noticeable change in the habitat and temperatures or humidity being too high or too low

Additionally, Loneliness if you’re raising one hermit crab only, as they’re generally social creatures.

Moreover, overstimulation can also be a major trigger to the hermit crab’s stress, which can occur due to being exposed to light and loud noises as well as handling them too often.

2 – Drying Out

While the sudden increase in temperature can be a major trigger to hermit crab stress, it can also cause them to overheat and dry out.

When crabs dry out and flake, they’ll be quite musty. To make matters worse, they’ll start to produce the pheromones of stress, which are more potent in that case.

These pheromones are also released in mating seasons to attract the opposite sex, which is usually during spring and summer, causing them to smell even stronger.

That’s why you always need to keep a bowl for bathing in the crab’s aquarium, as they can use the water to cool off and replenish their hydration levels.

3 – Molting

One of the major factors that will make a hermit crab stinky. Molting is a natural process in which a hermit crab will shed its exoskeleton and replace it with a new one as it grows.

The problem here is that this discarded exoskeleton, like the discarded limb mentioned earlier, will start to rot and emit a foul odor eventually.

While molting, hermit crabs are quite sedentary, which makes people often think that they’re dead, especially due to the strong stench of the rotting exoskeleton. Yet, you can tell that the crab is just molting by the following signs:

  • Digging burrows deeper than usual
  • Spilling water on the substrate on purpose to make it moist
  • Notable lack of activity
  • Turning ashy gray in color

Molting usually takes anywhere between a few weeks to months, depending on the size and type of the crab, so you have to give it some time.

4 – Excess Food

A lot of people are tricked into thinking that Hermit crabs are larger than they seem due to their huge shell habitats. However, the crabs are quite tiny with small bodies and even smaller appetites.

The bottom dweller has evolved through the years to eat as little as possible, and unless they’re molting, they’ll rarely eat a lot.

Supplying the hermit crab with more food than it needs won’t make it eat more. Instead, it’ll leave the food out, which will lead it to spoil and produce a rotten smell if you weren’t able to get rid of them, as hermit crabs may hide the food somewhere secure, making it harder to reach.

For that reason, try to feed the crab once a day and avoid providing them with more food than they need.

5 – Spilled Water

In addition to the hermit crab’s need for food, they also need saltwater for both bathing, hydration, and even drinking.

Hermit crabs have the habit of spilling the water on the sandy substrate while molting to form safe burrows.

At first, the spilled water will have a distinctive beach smell. But with time, the water will become stagnant and start to stink.

Similarly, water inside the crab’s shell might also become stagnant, as hermit crabs store water in their shells.

It’s extremely essential that you change the substrate and get rid of this water regularly to avoid the smell.

6 – Excrement Buildup

Unlike many living creatures, hermit crabs don’t eliminate out in the open. Instead, they resort to doing their business in the privacy of their own shell.

The problem is, hermit crabs might end up storing their excrement inside the shell for a considerable amount of time before they clean it out by flicking it on the substrate.

Hermit crabs developed this habit because it’s too risky for crabs to leave the shell while pooping, as they become an easy target to predators.

This leads to the poop building up inside the shell, which can cause a stinky smell after it decomposes, as it initially doesn’t have any specific smell.

In addition to poop, they can also urinate through the antennal glands in their head, which prevents the urine from mixing with drinking water stored in the shell. They usually pee on the substrate, which can also stagnate and produce a foul smell with time.

7 – Death

Lastly, while hermit crabs can be mistakenly perceived as dead while molting, a dead hermit crab will give off a seriously stinky smell of rotten fish.

Ideally, a hermit crab that is living in nature can live up to 30 years. However, due to varying levels of care and knowledge of caregivers in captivity, a hermit crab can live anywhere between a few months to about 15 years, making it quite difficult to predict a time where a hermit crab may die.

For those who have a small number of hermit crabs, spotting a dead one can be relatively easier. However, if you have multiple hermies, you may not be able to spot the dead one from the molting ones.

Also, as scavengers, other hermit crabs might start feeding on the dead one. But while this can reduce the smell, it’s recommended that you discard the dead crab because it may have ingested a toxin or a deadly microbe that will transmit to other crabs that will eat it.

How to Minimize the Stench of Hermit Crabs

Now that you have a better idea about all the reasons why a hermit crab might stink, here are some of the methods that you might want to consider if you want to minimize or prevent the strong foul smell that they can produce:

  • Clean Their Enclosure: The golden rule to prevent hermit crabs from stinking is to consistently clean their habitat, whether it’s an open tank, aquarium, pond, etc. Make sure that you create a weekly schedule to thoroughly clean every corner of the habitat.
  • Replace The Shells: As the hermit crab grows larger, they may require a larger shell to feel more comfortable and safer. This is essential to prevent buildup from forming inside the shell, which can stress the crab in the long run.
  • Clean and Replace Interior Substrate and Used Items: you might want to clean the substrate every week along with the enclosure, and scoop out any remains stuck inside.

Additionally, make sure that you replace the whole substrate every 2 to 3 months along with all decors and toys inside the enclosure.

  • Use Insects With Natural Cleaning Abilities: Hermit crabs like to feed on insects, so you can make your job a lot easier by opting for insects that have natural cleaning abilities, so they’re able to pick the residual wastes from the substrate.

Do Hermit Crabs Make a Good Pet?

Based on the previous information, you can notice that hermit crabs require special care and frequent cleaning in order to prevent them from stinking.

Additionally, they have a remarkable natural smell that isn’t bad but some people may not be able to tolerate it.

So the answer here depends on whether you’ll be able to provide the hermit crab with the love and care it needs.

Final Thoughts

With that said, you now have a brief guide that answers the popular question “do hermit crabs stink?”

As you can see, there are plenty of reasons why hermit crabs might start to emit a foul odor. While a happy and healthy hermit crab may not smell, a stressed one can start releasing nasty smelling pheromones.

Additionally, the smell could be a result of other factors, such as drying out and dehydration, spoiled excess food, build-up of excrements in the shell, and most notably, molting stench due to dead tissue

Although the last reason is purely natural, other reasons are easy to control and can play a huge role in keeping the crabs nice and clean!