The more time you spend with your hermit crab, the more it fuels your curiosity about them.
Ever wonder why we call them hermit crabs despite living in colonies? What about whether or not they can pee or poop like us?
Has it crossed your mind if your hermit crabs enjoy the kind of music you play around them? Do they even have ears to make them hear?
To help you better understand these animals, take time to read some of their fun facts.
Hermit crabs have ten legs, but you can only readily see the six front legs because of their primary functions.
Otherwise called their walking legs, each pair of the six front legs has a particular role.
For example, the first pair is for fighting and climbing. The second is for walking and foraging food, while the third is for mobility.
So what about the four back legs? The last two pairs of legs are small, so they keep the crabs inside their shells while moving around.
Here’s a strange fact about hermit crabs. They get rid of their pee through their heads!
As troubling as it may seem, you should understand that hermit crabs are built differently from humans. Let’s look at how they excrete fluid waste.
Hermit crabs have an excretory organ that works like our kidneys. You can find these specialized organs near the antennal or maxillary gland in the head.
These excretory organs maintain ionic balance within the animal’s body to remove the ammonia waste material. As a result, the fluid escapes through a tube opening in the base of the antennae or antennal glands.
Now, what about its poop? Hermit crabs poop like other animals, with dung ranging from black to brown. The size is also small, and the shape is like tiny sausages.
They poop inside their shells and use their back legs to discard them.
While their dung doesn’t stink badly, it can carry certain bacteria that cause diseases. Wear gloves if you’re trying to clean it from their tank.
Despite thriving in a tropical environment where the sun is always bright, hermit crabs are nocturnal and love the dark.
You can see them getting more into action during nighttime than daytime. If you closely observe your hermit crabs, you’d notice that they spend most of their time during the day snoozing.
So, don’t worry if they seem lethargic when you observe them during the day. Their body clock dictates that they rest in the morning as they’re nocturnal.
Hermit crabs in their native habitat tend to be inactive during the sun’s peak hours to protect themselves. Note that their abdomens don’t have a thick covering; thus, their only way to prevent dehydration is to hide.
Aside from moving around as soon as the sun’s down, hermit crabs forage for food at night.
Don’t think your crabs aren’t eating at all just because you haven’t seen them explore their tanks and look for their treat at nighttime.
Molting also happens at night. Total darkness helps your hermit crabs complete their molting process.
As previously mentioned, hermit crabs are nocturnal. They have compound eyes similar to insects. This unique feature helps them adapt to the poor light during their active hours.
These eyes have specialized structures called ommatidia that aid them to get around during the nighttime.
If you’re wondering what compound eyes are like, they’re not the same as what we have. They have thousands of smaller lenses to improve their viewing angle and quickly detect motion.
Hermit crabs aren’t reptiles. If we go back to the definition of a reptile, hermit crabs don’t fit the profile.
So what are reptiles? Reptiles are cold-blooded vertebrate animals with dry scales on their skin.
If you look at your hermit crabs, you’ll notice that their body doesn’t have scales. Instead, they have an exoskeleton that protects their soft bodies.
While they’re both cold-blooded creatures, it doesn’t mean that hermit crabs are reptiles based on this characteristic.
The answer to this question is a resounding yes. Crustaceans have segmented bodies, jointed limbs, and exoskeletons that protect their bodies.
These characteristics are present in hermit crabs. However, since hermit crabs can’t grow hard shells, they need to borrow from other animals.
Many say these creatures aren’t true crabs because they can’t develop their own. Despite the lack of “true shells”, unlike other crabs, they’re still crustaceans based on animal taxonomy.
Hermit crabs belong to Phylum Arthropoda and Subphylum Crustacea.
Invertebrate animals lack the characteristic backbone of vertebrate animals. Hermit crabs don’t have spines; thus, they’re invertebrate animals.
These crabs have an exoskeleton instead of a bony structure inside their bodies. The exoskeleton gives support as well as protection to its body.
While both mollusks and crabs have shells, the difference is that mollusks don’t have segmented bodies, unlike hermit crabs.
Hermit crabs aren’t mollusks, although they use the empty and abandoned shells of mollusks for protection.
Hermit crabs aren’t mammals because they’d share the same characteristics as us if they were!
So, how different are we from hermit crabs? Let’s start with the presence of a backbone.
Thanks to our backbones, we can support our bodies when we sit, stand, or move around. Hermit crabs lack these and rely on their exoskeleton for support and protection.
How about the presence of body hair or fur? Mammals generally have fur for warmth and protection, but hermit crabs don’t have these.
Lastly, hermit crabs don’t give live birth or feed their young from mammary glands. Instead, they lay numerous eggs and don’t look after their young.
That said, these crabs prove to be different from mammals. Mammals, including us, tend to nurture our young, which isn’t evident in hermit crabs.
Contrary to what the word hermit means, a hermit crab isn’t a creature that enjoys solitude. The term “hermit” refers to how each crab carries an individual shell and lives in it.
The independent endeavor to carry its secondary shell and hide in it for protection is where it got its name.
In their natural habitat, hermit crabs live in large colonies. They thrive best if they have lots of companions. You must’ve noticed how social these creatures are inside their tank.
It’s advisable to get two or more hermit crabs at once if you’re planning to adopt. Otherwise, your crab will die if it has no companions.
Hermit crabs change their shells as they grow in size. As a result, they leave their outgrown secondhand shells behind in search of new ones.
Hermit crabs choose the kind of abandoned shells they’d assume from other animals to simultaneously act as their shield and home. As they grow, hermit crabs would start to look for new armor that can play its part.
Interestingly, these creatures have a preference when it comes to their shells. One factor that would make them choose a particular shell over the others is the size.
Hermit crabs consider the diameter of the shell opening as an integral part of the shell selection process.
Let’s look at the types of shells they’d most likely choose
- Small hermit crabs prefer shells with openings that are ⅜ to ½ inches.
- Medium-sized hermit crabs like shells with openings ranging from ½ to 1 inch.
- Large hermit crabs opt for shell openings ranging from 1 to 1 ⅜ inch.
Aside from shell size, some hermit crab species have a preference in terms of the shell opening’s shape.
Take, for example, the common hermit crab species, particularly the Purple Pinchers. These crustaceans adore shells with round openings.
However, some species, like the Ecuadorians, favor shells with D-shaped openings because of their flatter bodies. Additionally, these shell types provide them with better protection coverage than other shells.
These creatures change their shells every 12–18 months after molting. Factors such as the hermit crabs’ species and shell availability can influence how often these animals switch shells.
For example, many hermit crabs will change their shells if they’re abundant. However, if they don’t see any available shells, they’ll try to stick to what they have.
As a result, the lack of available empty shells in their tank can be harmful to them.
Hermit crabs naturally occur in tropical countries where the sun is bright, and the temperature and humidity are just right. They’re abundant in the Indo-Pacific, Western Caribbean, and Western Atlantic.
The natural habitat of hermit crabs gives them easy access to land and water, which are vital for their survival.
These creatures enjoy living on the shoreline, where they can keep their gills moist while they’re on land. They need to have moist gills to keep their respiration process regular.
Hermit crabs can detect sound vibrations within a close radius, but their hearing isn’t good.
The vibrations they detect as sounds protect them from incoming predators.
Aside from that, they vibrate inside their shells to serve as a warning. They also rub off their body against the shell to produce a sound when they want to intimidate an enemy.
As much as you’d want this to be true, hermit crabs don’t have ears like dogs or cats. Instead, they use their antennae and the sensory hairs on their legs to catch vibrations from their surroundings.
While hermit crabs can detect vibrations, they’re limited to low to mid-range sound frequencies. The pulses must also be within proximity for the hermit crabs to catch the sound.
To sum up, hermit crabs have poor hearing, but that doesn’t mean that sound doesn’t impact them.
Hermit crabs may appreciate music or sound by picking up their vibrations.
Remember, hermit crabs don’t have ears, so the music you’re going to play around them should be something with a steady beat. It should also have a deep base sound for the crabs to detect.
The steady and repetitive beats from pop or rap music are recognizable to hermit crabs. The vibrations are easier to pick up, and they can react to them.
Your crabs will most likely react to louder rap music than a soft-sounding one.
As much as you want your hermit crabs to appreciate your choice of loud music genre, they’re not able to tolerate it.
You should note that playing music too loud and too near them can disrupt their sleep and eating sessions. Since they pick up sound from vibrations, the loud and the wrong genre of music can affect your hermit crabs.
If you’re fond of playing loud music with many deep bases, put your speaker far from the tank as much as possible. The throbbing from your speaker can disturb the hermit crabs and make them feel confused.
Hermit crabs can only pick up sounds with low-frequency waves. If the origin of the sound is too far or the frequency is too high, they won’t get distressed by it.
If your hermit crab tank is near the TV, your crab won’t notice the sounds coming from it.
Do Hermit Crabs Make Sounds?
If you hear a croaking sound in their tank, these are your hermit crabs creating sounds. Some would describe their sounds as similar to a cricket’s.
You’ll most likely hear the noise during the night when they’re at the peak of their energy level.
Hermit crabs heavily rely on their sense of smell more than their sense of hearing. Despite not having a nose to sniff, they have several “noses” in their internal antennae to compensate for it.
Tiny fine hairs, called aesthetascs, cover the inner antennae and make smelling possible for the hermit crabs.
They’re able to detect food and danger, as well as navigate their surroundings safely with the help of their antennae.
A study mentioned that hermit crabs couldn’t cover long distances when traveling. With an average speed of 21m/h, these crustaceans can only travel an average length of 21.6 meters per day.
Your hermit crab can’t get anywhere far within the day if it escapes its tank.
While you may want your hermit crabs to live longer, the average lifespan of these crustaceans is 15 years.
Give your hermit crabs the proper care they need by feeding them accordingly and providing them with an environment conducive to living.
That said, you should look into their tank’s temperature, humidity levels, availability of light, and easy access to water.
Note that they need both freshwater and saltwater for drinking and bathing purposes. You should also ensure that you prepare their water correctly.
There are many interesting hermit crab facts to learn. Now you know that despite being unique, they still share the same characteristics as other animals, like insects.
Additionally, the absence of a nose and ears doesn’t make them less than other animals, as they have other body parts that do the job. Hermit crabs can still hear, detect food, and recognize a potential threat using their sensitive legs and antennae.
I have a bachelor’s degree in Film/Video/Media Studies, as well as an associates degree in Communications. I began producing videos and musical recordings nearly 15 years ago. I am a guitarist and bassist in Southwest MI and have been in a few different bands since 2009, and in 2012 I began building custom guitars and basses in my home workshop as well. When I’m home, I love spending time with my three pets (a dog, cat, and snake) and gardening in my backyard. I also like photographing wild birds, especially birds of prey.