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How Big Do Hermit Crabs Get? (And How Fast Do They Grow?)

How Big Do Hermit Crabs Get? (And How Fast Do They Grow?)

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This post is written to the author's best knowledge and is not intended to be used in place of veterinary advice. In addition, this post may contain affiliate links. As an Amazon Associate I earn from qualifying purchases.

It’s fairly well-known that hermit crabs are good pets for people who don’t have a lot of space. For the most part, it’s easy to find room for a hermit crab habitat in your home.

When you see hermit crabs at pet stores, you’ll likely notice that they aren’t too big. Do these pets get a lot larger as they get older, though?

How big do hermit crabs get exactly? What should you expect as you continue to care for them over the years?

Read on to learn about average hermit crab sizes. You’ll also get information about the growth rate of hermit crabs and other related topics.

There Are Many Types of Hermit Crabs

Before going further into this topic, it’s important to recognize that there are many different types of hermit crabs out there. There are two major categories of hermit crabs.

You can buy land hermit crabs or marine hermit crabs. Marine hermit crabs live underwater and cannot survive on land.

These hermit crabs have gills and they breathe underwater. Land hermit crabs also have gills, but they’ve been modified to breathe oxygen.

Today, you’re learning about land hermit crabs. Land hermit crabs are the ones that people commonly buy as pets.

These creatures can be found in many pet stores around the world. They live in tropical regions such as the western Caribbean.

Different types of hermit crabs exist, and they have different qualities. One hermit crab might stay relatively small while another might grow to be fairly large.

So you can’t give a definitive answer when asking a broad question such as “how big do hermit crabs get?” It truly depends on the type of hermit crab you’re discussing.

Knowing this, it’s still possible to get an idea of how large hermit crabs are. You just have to understand that you need to look up specific information based on the type of hermit crab you’re interested in.

When buying hermit crabs, there should be information available about the species. If there isn’t, you might need to examine the hermit crab closely and look it up based on its physical appearance and characteristics.

Average Hermit Crab Sizes

Hermit Crab on the Edge of a Dish of Water

If you take all of the information about hermit crab sizes, you can get an average number. Typically, you can expect most hermit crabs to grow to four inches long.

This will take the crab quite some time to reach maximum growth. Hermit crabs go through molting periods when they’re growing so they can grow a new exoskeleton.

It’s also important to know that different crabs will grow to be different sizes. Some hermit crabs stay relatively small while others can grow to be even larger than average.

For example, a Caribbean hermit crab might grow to be six inches long. An Ecuadorian hermit crab will be much smaller by comparison and will only be about ½ of an inch long.

Strawberry hermit crabs are known to be fairly large and can reach six inches in size. Some hermit crabs will only be less than an inch long while others will be huge.

There’s even a hermit crab known as the coconut crab that is absolutely huge. This behemoth can grow to be approximately 39 inches long.

It’s a hermit crab that gets so large that it would be impractical to own one. Plus, these are rather ornery crabs that you wouldn’t wish to try to capture.

Coconut crabs only use shells from other species for a certain time. They stop doing this once they develop a hard enough exoskeleton.

Given all of this information, it’s easy to see that hermit crabs can grow to be quite big. Despite this, many hermit crabs will also remain small.

Hermit Crabs That Live Longer Grow Larger

Another thing to keep in mind is the lifespan of the hermit crab. Hermit crabs that live longer are going to grow larger.

Some hermit crabs live longer than others. There are hermit crabs that will only live for ten years.

Then there are hermit crabs that have the potential to live for thirty years or longer. Some hermit crabs are said to have lived to be seventy or older.

The long-lived hermit crabs are going to grow larger over the years. It makes sense that they would continue to grow and change as time passes.

Note that the average lifespan of hermit crabs that are sold as pets is usually ten years or longer. However, these hermit crabs often don’t live that long.

Sadly, people often wind up killing hermit crabs before they reach the ten-year mark. This is because they make mistakes when caring for the hermit crabs.

Hermit crabs are very sensitive to chemicals. Giving a hermit crab chlorinated water could easily kill it, and so could other types of chemical exposure.

It’s easy to kill hermit crabs if you’re not careful. They can die from a lack of humidity, or they can perish if it gets too hot in the tank and they dry out.

Keep all of this in mind so that you can do your best to protect your pets. If you want your hermit crabs to grow big and live for a long time, it’s important to care for them properly.

How Fast Do Hermit Crabs Grow?

Hermit Crab Hiding Under a Rock Decoration in a Tank

Typically, pet hermit crabs will reach their adult sizes in around two years. This can be a little bit different depending on various factors, though.

For example, nutrition might play a role. If a hermit crab is being fed well and is taken care of properly, it’ll have a better chance to grow.

However, you should also keep in mind that hermit crabs don’t stop molting. They just keep molting as they grow older, and that means that they continue to get larger over time.

So maximum size estimations should be taken with a grain of salt. Exactly how big the hermit crab will get depends on how long it lives, how often it molts, and other factors.

It’s true that most hermit crabs reach adult size by the time they’re two years old. After a hermit crab has reached adulthood, it’ll still molt.

Generally, hermit crabs will start molting every eighteen months once they’re adults. Molting is more frequent for juvenile hermit crabs.

Never Disturb Molting Hermit Crabs

Remember to never disturb molting hermit crabs. Hermit crabs are vulnerable when they’re molting.

In fact, you can cause hermit crabs significant harm if you startle them while they’re molting. Bothering a hermit crab when it’s molting might even cause it to die.

Leave hermit crabs alone when they start to molt. You should be able to recognize when hermit crabs are getting ready to molt.

Often, they will start to dig in the sand a lot when they’re preparing to molt. You might also see the hermit crab eating and drinking more than usual for a period of time.

Sometimes hermit crabs will purposefully spill water on the sand to get it moist when they’re getting ready to molt. They’ll also have eyes that look glazed-over.

Recognizing these signs can help you to understand what’s coming. You’ll know to leave the hermit crab alone once it buries itself in the sand.

Molting has the potential to take a very long time. It can take weeks or even months for the molting process to finish up.

Hermit crab owners sometimes get nervous when their pets are molting. They might worry that the pet has died.

Resist the urge to check the crab because you don’t want to disturb it. You could accidentally kill your hermit crab if you’re not careful.

If you suspect that the crab died, you’ll want to wait to see if it starts smelling bad. Dead hermit crabs have an atrocious odor that you’ll recognize fast.

Most people compare the smell of dead hermit crabs to that of rotting fish. You’ll want to dispose of the hermit crab’s body and replace the sand in the tank (after doing a thorough cleaning) as soon as you can.

How Much Does a Hermit Crab Weigh?

Hand Holding Large Hermit Crab

The weight of a hermit crab will differ greatly depending on the species that you’re looking at. Some hermit crabs are absolutely huge and can weigh a ton.

The coconut hermit crab that you learned about earlier can weigh nine pounds or more. That’s an extreme case since that’s the largest known hermit crab species.

Average pet hermit crabs aren’t going to weigh nearly as much as that. Some large pet hermit crabs might weigh around three pounds once they grow a lot and get older.

Many hermit crabs will weigh less than a pound, though. Remember that there are rather small hermit crab species out there such as Ecuadorian hermit crabs.

So you’ll have to look up the maximum expected weight of a hermit crab based on the species that it belongs to. You won’t be able to rely on general information to determine how much the crab should weigh in adulthood.

What Are the Best Pet Hermit Crabs to Own?

The best pet hermit crabs to own will be somewhat subjective. Regardless, some hermit crabs are more popular than others.

Below, you’ll learn a bit about some of the more popular hermit crabs that you’ll find at pet stores. These options are generally regarded as great ones for beginners and enthusiasts alike.

Caribbean Hermit Crab

Caribbean hermit crabs are a lot of fun to own. They’re likely the most common type of hermit crab that gets sold in pet stores, too.

These crabs are popular because they’re very easy to care for overall. Caribbean hermit crabs have gorgeous colors and they’re a lot of fun to watch.

When caring for these hermit crabs, be sure to put multiples of each shell size in the tank. You don’t want the hermit crabs to fight over shells as they have been known to do.

Strawberry Hermit Crabs

Strawberry Hermit Crab

Strawberry hermit crabs can get fairly big, and they’re also pretty. As you might expect based on the name, their bodies resemble strawberries.

They’re very active hermit crabs that love to move around and dig. If you’re looking for a hermit crab that’s fun to watch, you’ll be pleased with this option.

The only downside is that they’re a bit hard to care for. They’re more fragile than many other hermit crab types, and that might mean that they won’t live as long if you don’t do a good job caring for them.

Ecuadorian Hermit Crabs

You already learned that these crabs are rather small. They’re also very convenient to care for as pets.

One interesting aspect of owning these hermit crabs is that they’re speedy. It’s fun to watch them scurry around so quickly in the tank.

They seem to enjoy small and tight shells, too. Sometimes you might not even think that a shell will fit the crab, but it winds up working out nicely.

These crabs can be slightly aggressive, and they’re wary of people. Even so, they’re great pets because they’re highly active and fun to observe.

Ruggie Hermit Crabs

Ruggie hermit crabs are great pets, but they’re a little bit rare. Generally, you have to order these little crabs online since they don’t often get sold in standard pet stores.

Despite this, they’re great options for people who are new to owning hermit crabs. They’re not too big, and they’re easy to take care of.

It’s also nice that they’re very docile and chill little pets. They come in many colors, and you’ll love how neat they look.

Australian Land Hermit Crabs

Australian land hermit crabs should be on your radar as well. They’re from Australia and can come in several different colors.

Typically, you’ll see them being sold in white or brown. These hermit crabs are pretty easy to care for, and they look nice.

Blueberry Hermit Crabs

Finally, blueberry hermit crabs are rather popular due to how pretty they are. They are gorgeous with a blue coloration.

They’re pretty rare pets to find, though. If you see one of these in your local pet store, you just might want to buy it and count yourself lucky.

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