Coenobita clypeatus (also known as the Purple pincher or the Caribbean soldier crab) is a terrestrial hermit crab and a popular pet in the United States.
With their exotic appeal, these hardy land crustaceans have become popular pets due to their easy temper and relative ease of care. Purple pinchers can be kept in home aquariums, as long as their habitat is representative of their natural habitat.
This profile guide will give a special look into this remarkable species. You will know more about Coenobita clypeatus including their behavior, feeding preferences, ideal tank requirements, and how to take good care of them.
Quick Notes about Coenobita Clypeatus
|Name||Caribbean hermit crab|
||West-Indian land hermit crab, Purple-clawed hermit crab, Purple pincher, PP, Caribbean tree crab, Caribbean soldier crab|
|Scientific Name||Coenobita clypeatus|
|Tank size (minimum)||30 gallons (~120 liters)|
|Average size||up to 3 – 4 inches (7 – 10 cm)|
|Optimal Temperature||71 – 84 °F (22 – 29 °C)|
|Water type||Freshwater and saltwater bowls|
|Substrate||Sand and coco fiber|
|Life span||15 – 20 years (in captivity)|
|Color Form||Orange, reds, pink, cream, brown, purple, and peach|
Etymology of Coenobita Clypeatus
The name Clypeatus is of Latin origin, (clypeātus) meaning ‘shield shaped’ or ‘shield bearing’.
The name Coenobita is derived, via Latin, from the Greek words koinos (κοινός), “common”, and bios (βίος), “life” – meaning ‘A group of monks living in a community’.
Therefore, Coenobita clypeatus can be translated as ‘Shield bearing monk’.
As for their nickname, in the Leeward Islands of the Netherlands, these hermit crabs are called ‘Soldaatje’ (little soldier crab) because of a traditional story about invaders who run away after they heard by putting their ears to the ground and listening – that lots of ‘soldiers’ were on the march approaching their positions.
Distribution of Coenobita Clypeatus
Coenobita clypeatus is very abundant in subtropical and tropical islands in the Pacific, Atlantic, and Indian Oceans.
These hermit crabs can be found in north Florida, the Bahamas and Bermuda to the Gulf of Mexico, and northern South America.
Natuarl Habitat of Coenobita Clypeatus
Coenobita clypeatus may be found in a variety of habitats. Even more, according to the study, their populations can be roughly subdivided into 2 different ecological types: coastal and inland.
Generally, this species is found in coastal forests (up to 15 km) in areas covered with leaves and hard ground, beaches, and dunes of tropical and subtropical regions and in tight proximity to one another.
However, there are also individuals who have reached a more advanced stage of terrestrial life, the ‘inland animals.’ In most cases, these are older specimens, living in well-fitting and undamaged shells, and able to settle and maintain themselves in habitats rich in food, where there is a supply of fresh or brackish water.
Contrary to what might be expected, the largest numbers are mostly found in the more arid parts of its distributional area. Because of their way of locomotion, Coenobita clypeatus seems to avoid places with permanently humid areas (for example, marshland, freshwater pools, etc.).
These crabs prefer open grounds with relatively dry and hard soil.
However, in some areas of the xeric habitats of Mona Island (Puerto Rico), this species is mostly concentrated in the more humid habitats of the island, such as, in the coastal plain forest, in the caves, and in “bajuras” (natural depressions similar to sinkholes).
Therefore, as we can see, the habitat of Coenobita clypeatus is not very particular and can vary depending on the area.
Description of Coenobita Clypeatus
Generally, Purple Pinchers grow up to 2 – 3 inches (5 – 7 centimeters) in length. However, it is not uncommon to see old hermit crabs reach 4 – 5 inches (10 – 12 cm) and even larger. They do not grow fast and young crabs (under 2 – 3 years) rarely exceed 0.5 – 1 inches (1.5 – 2.5 cm) across.
There is a direct correlation between weight, shell size, and claw length. Large hermit crabs (baseball plus) can weigh a little bit more than 0.22 lb (100 g). Old specimens of Coenobita clypeatus may be as big as a man’s fist, reaching gross weights p to 1 lb (500 g).
Coenobita clypeatus can have several color morphs, the most common are oranges, reds, pink, cream, brown, purple, and peach. The older they get, the darker they become. Of course, it is also very individual, and some crabs can be extremely vibrant, or extremely pale.
The unique feature of Coenobita clypeatus includes the distinctive purple or blue defensive claw (which is where it gets its name).
As an anatomical trait, hermit crabs’ carapace covers only their cephalothoraxes. That is why they use a wide variety of gastropod shells to protect their abdomen from dehydration and predations.
Interesting fact: Everybody knows that hermit crabs use modified gills that have to be kept moist to enable proper respiration. However, they are also capable of breathing through their skin by the soft and moist tegument of the abdomen. For that, their body should also be moist.
Lifespan of Coenobita Clypeatus
Currently, there is no data available on the maximum lifespan for Coenobita clypeatus in the wild. However, some individuals were recorded to live to the age of 40 years!
In captivity, under optimal conditions, Purple pinchers can easily live up to 15 – 20 years.
Typical Behavior of Coenobita Clypeatus
Although they are considered to be nocturnal animals (primarily active at night), this species can also be active during the day hours.
According to the study, the diurnal activity of Coenobita clypeatus may be explained by the considerable differences between day and night temperatures.
For example, when at night the temperature drops below the optimum range, while during the day it stays within that range, the normal night-and-day behavior may be changed.
Note: Humidity also plays an important role in their lifestyle. At night time, the temperature (and evaporation) is lower, therefore, the relative humidity of the air is higher.
Generally, Purple pinchers are shy and usually retreat and stay motionless in their hiding places when disturbed.
These crabs enjoy climbing. In their natural habitats, they have been observed climbing trees to a height of 10 ft (3 m).
Interestingly, Coenobita clypeatus are relatively active animals. As a matter of fact, they can cover several kilometers in a few weeks (the shortest distance being about 2.5 mi (4 km), in eight days!).
Another interesting fact is that burrowing in loose substrate often occurred in captivity, but was never observed in the natural habitats.
Coenobita clypeatus are very social. They do not mind staying with other hermit crabs.
- Social: Yes
- Active: Yes
- Peaceful: Yes (generally)
- Burrowers: Yes (in captivity)
Diet of Coenobita Clypeatus
Coenobita clypeatus is a generalist scavenger/decomposer. In their natural habitat, their diet comprises of decaying animal and plant matter, fungi, fruits, berries, seeds, feces, etc.
For example, according to the study, their diet on Mona Island consists mostly of the feces of the Mona Island ground iguana (Cyclura stejnegeri). The main reason why these feces are so attractive to Purple pinchers is because they are already partially degraded and have a high caloric content.
Basically, these crabs are omnivorous animals and can feed on all kinds of vegetable matter as well as on protein-rich food.
- Even toxic fruits from the Manchineel tree are taken eagerly by Coenobita clypeatus.
- According to local fishermen, Purple pinchers can best be lured by grounds of coffee.
- These hermit crabs store large amounts of orange-colored fat in their abdomen.
- Lime-sinter stone enables a better water management.
In captivity, though, Coenobita clypeatus requires a good mix of meats and vegetation. Otherwise, if they do not get the right kind of treatment, even cannibalism may occur.
The food provided should be with the proportion of approximately 20% meat-based diets and 80% vegetables, etc.
Coenobita clypeatus requires nutrients like calcium, astaxanthin, carotene, and even antioxidants, just like humans. Hermit crabs express food preference, but only on an individual level.
Food diversity is extremely important. Multiple researches described that the behavior of hermit crabs often switches to unfamiliar food items.
Purple pinchers will consume foods like:
- carrots (these supply the carotene also needed to maintain their color),
- leafy vegetables,
- oak leaves,
- tree barks,
- nuts and seeds,
- sweet potatoes,
- red peppers,
- squash, etc.
Keeping and Housing Coenobita Clypeatus
Keeping Purple pinchers is not very complicated because these hermit crabs are pretty hardy animals.
Nonetheless, our goal is to mimic the natural habitat, therefore, we still need to address their core needs! Here are some care guidelines to help you out.
Tank Size (Enclosure):
A 10-gallon (40 liters) tank is recommended minimum for one small hermit crab. Large individuals 3 – 4 inches (7 – 10 cm) will require at least a 30-gallon (120 liters) tank.
Of course, having a larger tank is always preferable because it can be easier to make diverse areas for them to hide.
Important: Having a smaller tank will significantly limit their freedom. It will also make them more aggressive towards each other. Eventually, it will stress them and reduce their lifespan.
In Coenobita clypeatus, the water management is based on an equilibrium maintained by, the pressure of constant strong evaporation and a subtle method of uptake from the environment.
The presence of both freshwater and saltwater is absolutely necessary to create a favorable environment for this species.
Provide them with:
- a bowl of saltwater, and
- a bowl of freshwater.
Generally, the water only needs to be a few inches deep to completely submerge your hermit crab with a safe way to exit (for example, pebbles, a plastic mesh, etc.).
There is no need to make huge pools! Remember, in the wild, Coenobita clypeatus is usually absent in places where there is plenty of freshwater.
Interesting fact: Coenobita species is able to store water in its shell. This water can be used again partially as drinking water or to regulate the salinity of its shell water by diluting it with freshwater.
How to prepare saltwater:
To prepare saltwater you can use Instant ocean marine salt (or similar products – check the price on Amazon). This is a great choice. It is pretty cheap and will last very long.
Important: Do not ever use simple aquarium salt or table salt!
How to prepare freshtwater:
Ideally, we need to give them something like bottled spring.
Note: Distilled water seems to be the least suitable probably due to a lack of minerals in it.
If you decide to use tap water, let it age for 24 hours before using it. Tap water contains chlorine and it is toxic to them.
⦁ Substances like chlorine, chloramine, and contaminants should be removed from the water before adding it to the tank!
⦁ Do water changes every 2 – 3 days.
Coenobita clypeatus are cold-blooded animals. Their body temperature varies with the temperature of the environment. It means that they rely on an external heat source because they do not have control of their heat balance.
The optimal temperature range for Coenobita clypeatus is between 71 – 84 °F (22 – 29 °C).
At lower temperatures, they became more or less lethargic and all movements get much slower. If the temperature drops below 64°F (18 °C), this species shows very little activity.
Important: Heaters should never be placed under the crabitat because they can overheat your substrate and burn or kill molting hermit crabs there.
The best (safest) option will be to put the heater to the side of the tank, ideally, above the substrate line to heat the air.
Tip: If you have a 10-gallon tank, choose one, which is rated for at least 20 gallons. The difference in money is minimal but the benefit is huge!
Generally, Purple Pinchers tend to be more tolerant of fluctuations in humidity and/or temperature than most other hermit crab species.
Nonetheless, it was observed that these crabs orientated themselves on the relative humidity of the air in such a way that they always went to the place with the highest humidity.
Why is it so important?
Even though hermit crabs are able to live on land with their modified gills, their gills must be kept moist to breathe. Humidity slows down the rate at which the gills dehydrate.
According to the laboratory experiments, desiccation becomes lethal at weight losses of more than 15 % of the initial body weight.
Therefore, the recommended humidity levels in their habitat should always be above 70%. Ideally, it should be between 80 and 90 % all the time.
Note: Closed aquariums and terrariums are great to maintain humidity at a certain level. Whereas open-topped enclosures or wire cages are not suitable for that.
As I have already mentioned, surprisingly, Coenobita clypeatus is rarely observed to burrow in their natural habitats. However, burrowing in loose substrate often occurs in captivity.
These changes in behavior are not yet explained by scientists. My theory will be that the lack of space forces them to burrow instead of crawling away and hide.
Nonetheless, as hermit crab owners, we can’t do anything but adapt. Therefore, it is strongly recommended to have a substrate that allows them to burrow in their crabitat (for example, dirt or sand, not course rock).
|The general rule of thumb is that the substrate needs to be 5 – 6 inches (12 – 15 cm) deep minimum or at least twice as deep as your largest crab. If your setup allows it will be better to go for 10 to 12 inches (25 – 30 cm) of the substrate when Purple Pinchers are kept.|
Another important thing is substrate consistency. To dig underground and form a cave, the substrate should be moist enough to hold its shape (so-called “sandcastle consistency”). However, make sure not to waterlog the substrate to avoid the buildup of mold and other parasites.
Many hobbyists use a combination of sand and coco fiber (1:5 ratio). It is easy to maintain and it holds moisture very well.
- Playsand (It holds its shape very well when made sandcastle consistency).
- Pool Filter Sand (the same as playsand but has a uniform size).
- All-purpose sand (larger grain size compared to playsand and stay moist a little bit better).
Using only sand is possible but not recommended. Sand often becomes supersaturated even though the top couple of inches are dry.
Important: Never use calci sand! After drying and hardening in the crab’s shell, it may trap them inside to die.
Purple Pinchers need driftwood and natural vines for their daily maneuvering theatrics. Provide as many decorations as you can and you will make them happy.
Like most hermit crab species, Coenobita clypeatus relies on gastropod shells for protection as the crabs have a soft abdomen, leaving them vulnerable for predation and desiccation. In addition, the shell serves as a reservoir for fresh or saltwater stores and offers considerable thermal insulation.
Inadequate size or shape of shells may even affect their growth and morphology. For example, Therefore, finding and maintaining a suitable shell is of paramount importance for their survival.
- Coenobitans use enhanced chemosensory cues to pick up on death scents from recently deceased gastropods to retrieve intact shells.
- Coenobita species are also known for their way to modify both the inside and outside of their shell to make them more suitable for wear. For example, they can clean and thin the interior shell wall, remove the columella, clip the aperture of the shell, etc.
Ideally, when Purple Pinchers have a shell of the right size and the right shape, it allows them to withdraw completely in the shell and close the aperture of the shell with chelipeds and legs.
Even though there are a wide variety of shells that may be used by Coenobita clypeatus, some are better suited and preferred more often.
Through evolution, each hermit crab species developed a specific preference for shells with certain morphological traits that give them the most advantage to facing environmental stresses.
- Indian top-shell (Cittarium pica),
- Nerite (Nerita spp.,
- Astraea tecta (Lightfoot)
- Astraea caelata (Gmelin),
- Whelk shells
Warning: Do not use glass shells. First, these shells are very heavy for the hermit crabs. Second, they do not provide enough secrecy. In transparent shells, they cannot hide and it stresses them out even more.
|Important: provide them with lots of shells to choose from. The “Shell shop” should contain shells of different shapes and sizes. It is recommended to have at least 5 shells per Hermit crab, but more is always better.|
Handling and Bathing Coenobita Clypeatus
Handling. Purple Pinchers are not pets you can play with. Do not take them out just because you want to. You should really handle him as little as possible. They stress very easily.
Handle your hermit crabs with utmost care.
Be cautious too, they can snap at your fingers with their pincers. Generally, it does not hurt BUT you can flick your hand instinctively and your pet will go flying somewhere. They can get hurt easily, even with their hard shells.
Bathing. Despite popular practice, it is not recommended bathing hermit crabs. Remember, these animals have a mix of fresh and saltwater in their shell, if you bathe them, it can disrupt the balance.
Main Care Rules of Coenobita Clypeatus:
- Keep the environment humid consistently. The humidity levels should be regulated to 80 – 90 %, monitor this with a humidity gauge or hygrometer.
- The substrate should be kept damp ‘sandcastle consistency’.
- Provide as many hiding places as you can!
- Eliminate chlorine and contaminants from the water before usage.
- Replace the water at least once every 2 – 3 days.
- Don’t keep only one crab. Hermit crabs walk in pairs in the wild.
- Provide the various food items to diversify their diet.
- Replace the substrate bedding at least once every six weeks with a fresh one.
- Hermit crabs’ health needs to be maintained by separating them from specks of dirt, such as food and metabolic waste (feces and urine).
- Make sure the lid of the tank is closed tightly so that they cannot escape it.
Coenobita Clypeatus and Molting Cycle
As they grow, hermit crabs need to molt (shed the old exoskeleton and create new, bigger ones to accommodate their larger bodies).
The process of molting puts them in a very vulnerable state.
Recently molted hermit crabs are soft and also may desiccate very fast. That is why they usually borrow or hide as much as possible.
Molting hermit crabs should be disturbed only in emergency situations.
Interesting fact: The molting process largely takes place inside the shell.
Breeding Coenobita clypeatus
Unfortunately, it is close to impossible to breed Coenobita clypeatus in captivity. There are only a few documented successful attempts to breed them.
Currently, the pet industry completely depends on wild-caught species. A very low success rate is due to high mortality and the insufficient availability of certain environmental stimuli outside of its normal habitat.
Summary of facts about breeding Coenobita clypeatus:
- These hermit crabs reach sexual maturity at the second year.
- In young females, dark reddish-brown gonads can usually be seen through the transparent skin of the abdomen.
- Spawning requires less than a few minutes.
- Average size females can carry around one thousand eggs. Large females can have several times more eggs
- The freshly spawned eggs are firmly attached to the thin but extremely tough hairs of the branched pleopodes at the left side of the abdomen.
- Freshly laid eggs have a dark, reddish-brown color. Gradually, they change to light reddish-brown, light grey, and greyish blue. Dark eyespots indicated very distinctly the advanced development of the eggs.
- The development of the larvae takes place exclusively in normal seawater (a salinity ranging from 33-36% or SG = 1.023 – 1.025).
- Depending on the temperature, incubation lasts 3 – 4 weeks.
- Coenobita clypeatus releases its larvae in the week preceding the full moon.
- Their larvae cannot develop in freshwater or hypersaline water.
- Warm temperature (75 – 78 F or 24−26 C) is required.
- Coenobita clypeatus larvae undergo 6 marine larval stages before metamorphosing. According to the data from the laboratory:
|first||2.6-2.9 mm||3-5 days|
|second||3.2 mm||3-5 days|
|third||3.8 mm||3-4 days|
|fourth||4.6 mm||3-4 days|
|fifth||4.7-5.5 mm||4-6 days|
|Post-larva stage (glaucothoe)||4.3 mm||1 month|
Thus the total duration covers periods from 40 to over 60 days. The survival rate is extremely low.
Coenobita Clypeatus and Suitable Tankmates
The name “Hermit” is far from the truth. In reality, hermit crabs live and travel in colonies (and Coenobita clypeatus is not an exception). Therefore, It is recommended that in captivity they be kept in the company of two or more.
The lack of social need stresses them and shortens their lifespan.
They do not fight very often. Generally, it is usually over a shell dispute. However, newly molted hermit crabs can be attacked by others (they are attracted by the smell).
To prevent them from fighting, you can dip them both in the water bowl so they will smell the same. If it does not help, you need to isolate them for a few days.
Interesting fact: Hermit crabs communicate by sound.
Hermit crabs have a lot of character, personality, and can be a great addition to your home tank. They will certainly keep you occupied.
Having Purple Pincher hermit crab as pets can be exciting but it is one big responsibility. After all, these animals can live for many years. Therefore, you should only acquire these crabs if you are willing to give them special care and attention.
Lastly, instead of supporting the pet industry (they are all wild-caught), you can try to adopt them rather than purchase them.
- de Wilde, Peter Arnoud Willem Jacobus. “On the ecology of Coenobita clypeatus in Curacao with reference to reproduction, water economy and osmoregulation in terrestrial hermit crabs.” Studies on the Fauna of Curaçao and other Caribbean Islands 44, no. 1 (1973): 1-138.
- Rotjan, Randi D., Jeffrey R. Chabot, and Sara M. Lewis. “Social context of shell acquisition in Coenobita clypeatus hermit crabs.” Behavioral Ecology 21, no. 3 (2010): 639-646.
- Harzsch, Steffen, and Bill S. Hansson. “Brain architecture in the terrestrial hermit crab Coenobita clypeatus (Anomura, Coenobitidae), a crustacean with a good aerial sense of smell.” BMC neuroscience 9, no. 1 (2008): 1-35.
- Morrison, Lloyd W., and David A. Spiller. “Land hermit crab (Coenobita clypeatus) densities and patterns of gastropod shell use on small Bahamian islands.” Journal of Biogeography 33, no. 2 (2006): 314-322.
- Nieves-Rivera, Ángel M., and Ernest H. Williams Jr. “Annual migrations and spawning of Coenobita clypeatus (Herbst) on Mona Island (Puerto Rico) and notes on inland crustaceans.” Crustaceana (2003): 547-558.
- Hunt, Harley. “Terrestrial Soldier Crab (Coenobita clypeatus, Fabricius 1787) and Cerion spp.(Röding 1798) shell relationship on San Salvador Island, Bahamas.” (2021).
- Flesner, Tricia. “Food Preference in the Purple Pincher Hermit Crab (Coenobita clypeatus) Food Preference in the Purple Pincher Hermit Crab (Coenobita clypeatus).”
- Alander, Kerstin, Emily Bach, Emily Crews, Megan Smith, Tom Lacher, and Jim Woolley. “Distribution of Hermit Crab Sizes on the Island of Dominica.”