Hermit Crabs: Characteristics, care, breeding and more

Can you imagine how would it be to take your house everywhere? This is the life of the hermit crabs, creatures that seem to live to move and take care of their house.

These crustaceans, despite being crabs, are more related to lobsters than to their species. The hermit crabs lack a hard shell like the others, so  they adopt the empty shell of the sea snails and other mollusks to protect their bodies. This is how the life of these animals takes place, looking for a more comfortable house and protecting it.

Hermit Crabs Main Characteristics  

These strange creatures receive the scientific name of Bernhardus Pagurus, but they are better known as hermit crabs or soldier crabs. These crustaceans belong to the family of decapods, and there are about five hundred (500) species of these crabs around the world. Most hermit crabs are aquatic, but there are also some terrestrial crabs. The hermit crabs use snail´s shells or other mollusks to cover their bodies, which unlike those of other crabs is  soft and does not harden. For this reason, they resort to the corpse of another species, but they do not take advantage of it as carrion, but to inhabit it. The soldier crabs walk through the seabed, eating and growing, and if they find a dead snail the hermit crabs leave their old shells, to adapt to the new empty conch shell, as long as they feel more comfortable and protected in it.

Perhaps this phenomenon of natural adaptation has inhibited these creatures from evolving, since with this behavior they have managed to protect themselves; and have refused to acquire new more armored forms as did other species of their same class, which are better equipped for defense. As decapods they are, these crustaceans have ten legs of which the first pair of them are pincers. The right is larger than the left, and both have a rough and grainy surface. These pincers are employed to capture and manipulate their food and also to defend themselves against predators, by blocking the entrance to their shell, and to woo the females of their same species. The next four legs that follow the pincers or tweezers are employed to walk, while the rest are used to hold and stay inside the shell. They also have two eyes on small appendages, and two structures similar to a pair of antennas, which are called antennular flagella, which allow the hermit crabs to feel everything that is in their environment.

The front portion of the hermit crabs, that is, what we can see outside the shells they carry on them, is covered by a rigid exoskeleton, while their abdomens and backs are soft. For this reason, these crabs twist their abdomens to enter into a shell that provides them enough protection. In addition, when the hermit crabs feel in danger, they use their legs and pincers to block the entrance of their shells.

 Size and Weight

Just as there are different species of hermit crabs, there are also various measures for these crustaceans. According to the most recent studies, there are species of this animal that only measure nineteen (19) millimeters, that is, that they are a miniature. The most common, tend to measure ten (10) centimeters in length, and a weight of  four (4) kilograms; but it is known of species that have measured up to thirty-Hermit crabs: Aniculus ursusfive (35) centimeters in length, which makes them look as a monster, especially when compared   with the miniature species. As these crabs grow, their shells become small for them, so they have to find another one where they feel more comfortable and protected. They must get a house very quickly, because while they are in this situation, they are more vulnerable to predators.  For this reason, many times they have to fight bloody battles, to get the shell that best suits their body. When they are in their natural habitat, there are many specimens and few appropriate shells, so crabs fight with their rivals to get the best conch. But sometimes, the crabs do not conform, and instead of looking for a shell, they prefer to fight with another specimen to steal its shell.

Let´s watch them

Hermit Crabs Alimentation Habits

In the same way that the coconut crabs eat everything, so are the Hermit Crabs. They are also known as sea vacuum cleaners, because they eat almost anything. These crabs are omnivores, so their diet includes worms, snails, mussels, crustaceans, larvae, plants. Since they have a scavenging nature, they are also capable of eating dead animals. These creatures,  in the same way than blue river crabs, can also obtain their food, by filtering organic particles from the water.

What do hermits Crabs in Captivity Eat?

Unfortunately, there are many people who like to have these little animals as pets, because according to them they are very easy to care for and feed. However, if you are one of them you should know the following:

When held in captivity, hermit crabs can eat cooked chicken, beans, peas, raw fish, corn, bananas, onions, carrots, all fruits, including citrus fruits, and much more. The only thing these crabs apparently do not eat is avocado, because it is poisonous for them.

How Hermit Crabs Breed?

These crustaceans are oviparous and only reproduce twice a year. The hermit crabs that live on the seashore usually mate between the months of January and February. As far as of those that live in the depths, there are documented cases of females that can carry the eggs in their wombs for up to a year. After the copulation, the females carry the eggs under their abdomen for approximately two months. Then she releases them into the sea. Hundreds of larvae called zoes emerge from the eggs, and remain a few weeks adrift as part of the plankton.

Life Cycle of Small Hermit Crabs

Both the first and second stages of the life of the hermit crabs occur within the eggs. After having passed several changes in their lives, the stage called megalopa is reached. As they grow, these crabs often shed their skin, and only until they have their two tweezers and four antennae, is it possible to find a shell that allows them to protect their bodies, and thus be able to go out to the beach. When they are small, the hermit crabs are characterized by being on the seashore, where they live most of the time, and this is where they get the scallops shells, and dog horns. Hermit crabs reach sexual maturity when they reach one year of age; and these amazing crustaceans can live from thirty (30) to seventy (70) years. During this time of life, they will have to change in different occasions of shell; and this never ceases to represent a danger to crabs, since while they are detached from a shell, to enter a new shell, they are vulnerable to attack by any predator.


Hermit Crabs´ Common Habitats

These crustaceans can be found all over the planet.  Since theses crabs are aquatic, and coastal aquatic, they can live both deep in the sea, about one hundred and forty (140) meters, as in the reefs, in the rocky areas of the coast, and of course, in the sand on the shore of the beaches. When they are on land, they prefer to live hidden under the rocks, but with the condition of being close to the coast.  However, they always need to go to the water to keep their gills wet, to survive and to reproduce The only freshwater species of hermit crabs is the Clibanarius fonticola.

Hermit Crabs´ Distribution

Although Hermit crabs prefer the tropical climate, they usually live on the American and European continents. They can be found, from Alaska to Mexico, and from Guatemala to Chile. This means that these crabs are present throughout the Americas. They can also be found from the Bering Strait, to the northern part of Japan, in the Mediterranean Sea and also in the Baltic Sea. Generally these crabs can live in oceans, rivers, lakes, coasts,  and estuaries.

How Hermit Crab live in Captivity?

When these animals are kept in captivity, it is necessary to provide them with a container large enough so that they can feel at ease. These animals are constantly growing, so their size should be taken into account. As long as there is nothing where the crab can escape, it is not necessary for the container to have a lid. However, a lid  can help maintain moisture, if it is a place with a dry environment.

When the hermit crabs are in captivity, they usually bury themselves in the sand to change the skin. For this reason it is required that the container has a thick layer of it, so that he can carry out his molt. Do not use soil with added nutrients, or with a very acid soil, because they can be harmful to the animal; instead, you can place coconut fiber, which is a good substrate for them.

The habitat of captive crabs should provide them with hiding places. This can be achieved by placing tree bark, some leaves, or a log of wood in the container, so they can feel safe when they need to hide. It must also have stones, moss or artificial plants, which resemble a bit its natural habitat.

It is not very advisable to have many of these animals in a container, because they usually fight each other, for the domain, and also for the shells. If you are thinking about having more than two specimens, you should use an aquarium of 15 up to 25 gallons.

On the other hand, it should be also known, that it is not a good idea to have only one of them, since they are quite social creatures, and being alone makes them feel stressed. So, 3 or 4 hermit crabs in an aquarium of 15 up to 25 gallons is the most advisable environment for them.

Hermit Crabs´ Behavior

The life of these crabs takes place around their shell or carapace, because since they are born, a few weeks later their race begins to provide themselves with one of them. As they grow up, they need to change it, since it becomes small for their body, and they have to look for another one that provides them with greater comfort. 

The hermit crabs can detect when a mollusk is losing its shell, and they wait for the precise moment to take advantage of the corpse to occupy its shell. They can even fight bloody battles for one of these shells, and one specimen can attack another in some cases.

The shells of the mollusks retain water, which is very useful for the gill respiration of the hermit crabs. When they are exposed to find a new shell, they choose a shell where they can fit completely, as this is their defense mechanism against predators, or potential rivals who want to evict him from home. To increase their protection these crustaceans are commonly associated with anemones so that they intimidate predators, and they are reluctant to attack them.

Behavior in Captivity

In general, the hermit crabs have an affable and calm behavior, even in some cases they could be classified as timid. They can be seen walking day and night in the container or aquarium, but they are susceptible to sudden movements or vibrations, so they startle, and quickly retract in their shells to get safe. Once they notice that the danger has passed, they leave again to continue with what they were doing. When they shed their skin, they like to do it in privacy, burying themselves into the sand; if for some reason they are disturbed, they retract in their shell again, until the supposed danger passes. That is why, when it is time to change their skin, you should leave a space to the crab, so that it does so without any type of interruption. You must provide the crabs in captivity with enough shells to have them from which to choose. Although on many occasions, even being at liberty, not getting an adequate shell, is satisfied with any type of container that can fulfill this task.

It has been seen the case of hermit crabs on the beach, which even use bottles of soda as shell. This fact should make us reflect on the use that we make of these places of distraction and tourism, since nobody should throw garbage in them, because it generates pollution and damage to all species.

The Hermit Crabs in Gastronomy

Although many people are lovers of hermit crabs to raise them as pets, many others like them more to enjoy them in their kitchen. For example, in different islands of the world, both European and Caribbean, these crabs are cooked on the grill and marinated with lemon and pepper, to sell at a high cost to tourists. It is known that in the Balearic Islands, they cook them with everything and anemones, which they call in Catalan «Figues», which means, figs. To do this, they cut them laterally, and remove all the sand they may still have in their gastric cavity, and then take them to the fire, until they are very well cooked.

According to the experts in this matter, special care must be taken when cleaning the shells, since the anemones have stinging cells that turn out to be irritating to the face and eyes of certain people. So, if someone is allergic to shellfish, he or she shouldn´t prepare, let alone consume this crab. As these animals have an extremely hard cephalothorax, the only part that can be consumed of the hermit crab is the abdomen, which according to those who have consumed it, has an exquisite taste, but since it also contains very little meat, it takes more than five hermit crabs to satisfy a single person. This crab is also often used in paellas, rice dishes, and seafood wraps.


How to Breed Hermit Crabs

It was  thought a few time ago, that hermit crabs would not breed in captivity, but recently some have successfully bred with some suitable conditions.However, keep in mind that it is much harder to successfully hatch and raise them on land.

If you want to do it, you should follow these instructions.


1 Determine the sex of the hermit crabs by examining their legs. Female crabs have well-developed legs, called pleopods, on the left side of their abdomen, and also have a gonophore on their second pair of locomotors legs. It is through this opening that the sperm is deposited into the female´s body and through which her eggs are laid.

As for male crabs they have very small pleopods, and their last pair of legs resemble tubular structures.

2 Observe the mating between your pair of adult hermit crabs. It is common for them to partially come out of their shell and for the male to transfer a spermatophore to the gonophore of the female.

3 Be alert to the presence of eggs in the female’s body.

4 Observe the eggs for a period of one month, their color usually changing from red to gray.

5 See the female closely near the end of that month’s period. It is common to see it pass clusters of eggs from one set of legs to another and move them towards the tip of their pincers. Then the female throws the mass of eggs into the water where they subsequently hatch.

6 Watch for larvae. You can place them in aerated cups. Put also some small shells in this container, which the larvae can use. Put the cups into a sand substrate. Feed the larvae with brine shrimp.

7.- Put young hermit crabs in a transition tank, which should be  decorated half beach and half marine water. It is a good idea to put a coconut inside the tank, as well as some nice shells. Make sure the young hermit crabs have a ramp going from the sand to the water containers

8.- Keep in mind that juvenile hermit crabs usually eat their siblings.

9.- Use regular marine salt water for the transition tank.

10.- Feed young hermit crabs a with a high protein diet, which can include  marine copepods, krill, crayfish, shrimp granules and spirulina.

11.- The best idea is to  use  a 10 gallon tank  for breeding these crabs, with a range temperature between 22 and 26 celsius degrees, always breed  them during spring or  summer.

Finally when you see them changing their shells don´t get scared


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