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Do Hermit Crabs and Shells Have a Symbiotic Relationship?

Do Hermit Crabs and Shells Have a Symbiotic Relationship?

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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.

For hermit crabs, having the protection of a shell is absolutely essential. One thing that most people know about hermit crabs is that they live inside shells.

The relationship between hermit crabs and shells is actually pretty interesting. If you don’t know a lot about hermit crabs yet, learning more about this topic will be beneficial.

It’s important to understand what shells mean for these creatures. If you’re going to keep a hermit crab as a pet, you’ll need to provide it with various shells of different sizes.

Read on to learn more about hermit crabs and shells. You might gain a new appreciation for hermit crabs once you’ve learned everything.

Do Hermit Crabs Have a Symbiotic Relationship with Shells?

Saying that hermit crabs have a symbiotic relationship with shells isn’t quite accurate. You see, a symbiotic relationship is one where both parties benefit.

A hermit crab clearly benefits from using a shell. They use the shells of sea snails (and sometimes other creatures) to make up for inherent weaknesses.

These shells don’t benefit in any way from being used by the hermit crab, though. The shells themselves have simply been left behind by dead sea snails.

The sea snails are no longer around. Since the sea snails are dead, they can’t benefit or form any type of relationship with hermit crabs.

Indeed, if the sea snails lived, the hermit crabs might try to kill them to take their shells. So if anything, the relationship would be antagonistic.

Regardless, you should know that hermit crabs generally like to keep things safe. They prefer to seek out unoccupied shells that are left behind by dead sea snails.

So hermit crabs don’t really have a symbiotic relationship with sea snails or shells. Shells are inanimate objects and aren’t capable of forming relationships with living creatures.

Why Do Hermit Crabs Need Shells?

Hermit crabs need shells because they need protection. They have soft bodies that would be very easy for predators to penetrate.

If a predator attacks a hermit crab while it’s outside of its shell, it’s likely that the hermit crab will die. A shell is hard and provides ample protection.

The shell makes up for something that the hermit crab is lacking. Hermit crabs can’t protect themselves reliably unless they make use of these shells.

It’s interesting to see how hermit crabs have adapted to use shells that are left behind by sea snails. They don’t have protective shells of their own, but they’re able to utilize resources that can be found in the environment to make up for an inherent weakness.

Hermit crabs are able to use shells very well. Two of the hermit crab’s legs are specifically used to hold onto the shell.

They have become very adept at moving around inside the shells. It’s impressive to see how well hermit crabs are able to use the shells.

Hermit Crabs Can Retreat Inside of the Shells

When threatened, hermit crabs might choose to retreat inside of the shells. Sometimes predators will attack hermit crabs and they will need to hide in an attempt to survive.

This gives the hermit crab a chance to survive the encounter. If the predator is not able to successfully pull the hermit crab out of the shell, it will likely choose to move on and look for other prey.

Hiding is sometimes the best option that hermit crabs have for protection. The shell is hard and can withstand attacks from predators.

It isn’t necessarily easy for all predators to pry hermit crabs out of the shells either. So hiding is an important tool that hermit crabs can utilize in a pinch.

Hermit Crabs Store Water in Their Shells

Having access to water is important for hermit crabs. They use water for many different things.

These creatures need access to both saltwater and freshwater. They will store water in their shells for later use.

Water is used for many purposes. The hermit crabs might drink the water as necessary for survival purposes.

The water is also used to keep their gills moist. Hermit crabs have modified gills that can breathe oxygen, but they must remain moist to do so.

They’re able to store water in their shells so that they won’t run out. It’s just another interesting way that hermit crabs use their shells for survival purposes.

Hermit Crabs Rarely Leave Their Shells

It’s not common for hermit crabs to leave their shells. Typically, a hermit crab will only leave its shell when it needs to change shells.

Otherwise, it might leave its shell if it’s in a particularly perilous situation. However, hermit crabs are generally very reluctant to abandon their shells.

Shells provide protection and hermit crabs feel incredibly vulnerable outside of their shells. You shouldn’t see hermit crabs leave their shells too often.

Hermit Crabs Must Change Shells Occasionally

Occasionally, hermit crabs are going to need to change shells. As hermit crabs grow, they will need to find larger shells.

They will look for new shells and try them out to see if they’re a good fit. Sometimes you might see hermit crabs go back and forth between a few different shells as it tries to figure out what the best fit is.

Hermit crabs will molt and grow many times during their lives. So if you keep pet hermit crabs, you’ll see them change shells somewhat often.

This is why it’s important to keep many shells of different sizes in the habitat. These are present to give the hermit crab choices when it grows and needs to choose a new shell.

Final Thoughts

Hermit crabs don’t have symbiotic relationships with shells or sea snails. They simply utilize the shells that are left behind by dead sea snails.

Regardless, it’s interesting to note how important shells are to hermit crabs. Without shells, hermit crabs would be incredibly vulnerable.

The shells make up for weaknesses that hermit crabs have. They’ve adapted to use shells for survival purposes and they’re very good at utilizing them.

It’s intriguing to see hermit crabs use their shells for survival. They can hide inside them and they can even store water in them.

You know that shells are very important to hermit crabs. If you buy hermit crabs as pets, be sure to keep plenty of extra shells of various sizes in the habitat with them.

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