Coenobita brevimanus – Detailed Guide: Care, Diet, and Breeding

Coenobita brevimanus – Detailed Guide Care, Diet, and Breeding

Coenobita brevimanus, commonly known as Indonesian crab, Brevi, Indo, or Purple hermit crab, is a species of coastal living terrestrial hermit crabs. These cute and sociable hermit crabs have a lot of personalities and are a load of fun to watch.

Nowadays Coenobita brevimanus is not very common in the aquarium trade. Overharvesting them for the pet trade, transportation stress and lack of initial care make these hermit crabs more prone to losses. As a result, even sellers try to stay away from so-called sensitive species.

Although at first glance Coenobita brevimanus does seem to require little maintenance, it is not completely so. In captivity, their habitat should be representative of their natural habitat; their diet should be diverse with provided daily care.

Once established these hermit crabs become relatively hardy and easier to keep.

In this guide, I gathered everything we currently know about Coenobita brevimanus including ideal tank setups, healthy diets, breeding, compatibility, etc.

Coenobita brevimanus is listed as “vulnerable” under the World Conservation Union (IUCN) Red List and was regarded as natural monument in Japan.

Quick Notes about Coenobita Brevimanus

Name Coenobita brevimanus
Other Names
Indonesian crab, Brevi, Indo or Purple hermit crab
Scientific Name Coenobita brevimanus
Type Terrestrial
Tank size (minimum) 30 gallons (~120 liters)
Keeping Moderate
Breeding Very Difficult 
Average size up to 3 – 4 inches (7 – 10 cm)
Optimal Temperature 80 – 90 °F (26 – 32 °C)
Water type Freshwater and saltwater bowls
Humidity >80 %
Substrate Sand and coco fiber
Diet Detritivore /omnivore
Temperament Peaceful. Social  
Life span 5– 8 years (in captivity)
Color Form Purple and brownish-red brown

Etymology of Coenobita Brevimanus

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’.

The name Brevimanus is of Latin origin, meaning brevi = short (small), and manis = hand.

Therefore, Coenobita brevimanus can be translated as ‘Monk with short hand’.

Distribution of Coenobita Brevimanus

Coenobita brevimanus is native to the east coast of Africa and the south-west Pacific Ocean Currently, this species is distributed throughout the Indo-Pacific area. These hermit crabs have been reported in East Africa, the Philippines, India, Indonesia, Japan, Malaysia, China, and Taiwan.

Note: They are also present in other countries because of ornamental tourism.

The southern islands of the Japanese archipelago are the extreme northern limit of the biological range of this species.

Natural Habitat of Coenobita Brevimanus

Coenobita brevimanus has subtropical and tropical distribution.

This species is the most terrestrially adapted Coenobita. These hermit crabs primarily inhabit inland, arid scrubland, coastal forests, and rainforests in lower density.

In the wild, they can be often found on rocks or under the woods between the caves up to 1- 1.5 km from the shore (rarely near the shore).

Description of Coenobita Brevimanus

Huge Coenobita brevimanus – Detailed Guide Care, Diet, and Breeding
photo credit to SojMad

Coenobita brevimanus is a large land hermit crab. Fully grown individuals reach up to 6-8 inches (15 – 18 cm) long and weigh up to 8-10 oz (230-300g). It makes them one of the largest land hermit crabs from the genus Coenobita.

Note: However, in captivity, the average size of the adult crabs is often about 2 – 3 inches (5 – 8 cm) long.

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 predation.

Distinguishing characteristics of Coenobita brevimanus:

  • Color. Body color is mostly uniform purplish which is why this species is often times mistaken with Coenobita violascens. However, in some cases, it can also be brownish-red.
  • Claw dimorphism. Even compared to other species in its genus, these hermit crabs are identified by their disproportionately large bulbous left claw without stitch marks.
  • Eyes. The eyes are round and the eye stalks are brown to black.

Interesting fact: According to the study, the cuticle of the hermit crab’s left claw is a hemispherical laminated structure that has 5 sublayers with distinct microstructures that helps it to protect its body against attack from predators.

Lifespan of Coenobita Brevimanus

Currently, there is no data available on the maximum lifespan for Coenobita brevimanus in the wild.

According to Wikipedia, this species can live up to 70 years!

Note: I need to say that all my attempts to find the source of this data did not succeed. However, considering the fact that bigger species of hermit crabs live longer, I would not be surprised to see 40 or 50 years old Coenobita brevimanus.

Nonetheless, in captivity, under good conditions, Coenobita brevimanus can live up to 5 – 8 years.

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Typical Behavior of Coenobita Brevimanus

Indonesian crabs are nocturnal and will spend most of their days hidden from the light in order to avoid being seen. It is at night when they truly come alive, roaming around the tank looking for food or a new hiding spot.

Once settled, their behavior will become more outgoing and they will come out more often even during the daytime.

Note: The diurnal activity of Coenobita brevimanus 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.
These hermit crabs are considered to be social animals and benefit from being in the company of their own. It makes their life richer and less stressful.

They act in conventional ways by toppling over one another. They may have pushing contests from time to time and feeler fights — whereby they smell one another.

Coenobita brevimanus needs a lot of time to accustom to a new environment. So, they can be shy and reticent for months. However, eventually, they become pretty active and not timid at all. They like to climb and explore every nook and cranny in the tank.

When hermit crabs feel threatened, their body retracts into the shell whereas their left claw, serving as a shield, closes off the aperture of the shell to protect its body. They can even chirp when they feel intimidated and will stick out their big claws defensively when picked up.

Coenobita brevimanus tends to burry for a long time (even without molding).

Features:

  • Social: Yes
  • Active: Yes (once settled)
  • Peaceful: Yes (generally)
  • Burrowers: Yes

Diet of Coenobita Brevimanus

Coenobita brevimanus is a generalist scavenger/decomposer of terrestrial debris. In their natural habitat, they accelerate the decomposition of organic substances, and act as seed dispersers and also as nectar-feeding pollinators.

Basically, it means that these hermit crabs will add to the diet whatever they can get their claws on.

However, in captivity, for the best growth, it will be better to provide Coenobita brevimanus with a good mix of meats, vegetation, and cellulose.

General recommendations:

The food provided should be with the proportion of approximately 20% meat-based diets and 80% vegetables, and foods with high levels of cellulose.

Keep in mind that hermit crabs express food preferences, but only on an individual level. In addition, their behavior often switches to unfamiliar food items.

Coenobita brevimanus also requires nutrients like calcium, astaxanthin, carotene, and even antioxidants, to be healthy. Therefore, food diversity is extremely important.

Important: Avoid or be very careful with spicy, sour, fatty, salty, sweets, and food from the table. For example, foods high in oxalic acid also impede the absorption of calcium by binding the mineral.

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Keeping and Housing Coenobita Brevimanus

Although these hermit crabs have been kept as pets for many years, surprisingly, they are not well studied.

So, the best we can do is to find out their preferences and mimic their natural habitat. Here are some care guidelines to help you out.

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Tank Size (Enclosure):

First of all, Coenobita brevimanus is a large species. These hermit crabs need a lot of space to move around. Remember, even if they are not very active during the day, they easily compensate for it at night.

A 10-gallon (40 liters) tank is recommended minimum size for one small hermit crab. Large individuals 3 – 4 inches (7 – 10 cm) will require at least a 30-gallon (120 liters) tank.

Important: Having a smaller tank will significantly limit their freedom. It may also make them more aggressive towards each other. Eventually, lack of space will stress them and reduce their lifespan. 

Water:

Same as all the other terrestrial hermit crab species, in Coenobita brevimanus 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 water is absolutely necessary to create a favorable environment for them. 

According to the study, in Coenobita brevimanus the osmotic concentration of serum was an average of 80.3%. It means that this species does not depend on the sea for a source of water. Unlike beach-dwelling Coenobitids, these hermit crabs can distinguish the odor of fresh water from that of seawater, and they intake only freshwater.

Note: In the same study, it was described that small crabs were also found on the seashore at nighttime, and they assumed that the reasons for the migration may also be drinking seawater.

Although fully grown individuals may suffice/prefer freshwater, it would still be better to 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, these hermit crabs are usually not found in places where there is plenty of freshwater.

Interesting fact: Without water most hermit crabs become more aggressive. Coenobita species can tolerate dehydration to the maximum tolerated 28% loss of body water. Experiments had revealed that a further 24 hours of dehydration would lead to a comatose state and, invariably, death within another few hours.

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. 

You can also use a water conditioner. For example, Seachem Prime will remove also toxic gases, and bind to heavy metals, any ammonianitrites, or nitrates present for up to 48 hours.

Important:

  • 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.

Temperature:

The optimal temperature range for Coenobita brevimanus is between 80 – 90 °F (26 – 32 °C). They do love warm temperatures. At lower temperatures, they became lethargic and all movements get much slower.

Note: Hermit crabs are cold-blooded animals. It means that they do not have control of their heat balance. That is why their body temperature varies with the temperature of the environment.

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 as well.

Humidity:

Humidity levels are very important.

Coenobita brevimanus has an abdominal lung which is adapted to their terrestrial lifestyle. Thus, they need moist, and humid air to breathe. The humidity level should be more than 70%. In ideal range would be between 80 and 90 % all the time.

This hermit crab specie loves fogger more than any other species. They often sit in the mist and groom. Even if you simply mist their enclosure, you will see how active they become right away.

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Substrate:

The tank should be filled with a substrate into which they can burrow. Coenobita brevimanus burrows to chill, rest and molt.

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.

In order to dig underground and form a cave, the substrate should always be kept moist enough. It means that it should hold its shape when you squeeze it. However, not so wet that it drips or pools water.

To get “sandcastle consistency”, a mixture of cocofiber and sand will be the best option.

Many hobbyists use a combination of sand and coco fiber (1:5 ratio). It is easy to maintain and it holds moisture very well.

Tip: There is a simple trick to test the consistency. Take a pencil and stick it all the way down and pull it back up. If the tunnel doesn’t collapse, your substrate is good enough.

The substrate may also require maintenance such as spraying with fresh dechlorinated water on a regular basis in order to keep it moist enough since the moisture in it will evaporate over time.

Sand options:

  • 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).
Important:

  • Do not ever use saltwater to maintain moisture as salt does not evaporate and can lead to a harmful salt build-up.
  • Never use calci sand! After drying and hardening in the crab’s shell, it may trap them inside to die.
  • When they are under the substrate, DO NOT EVER dig them up!

Lighting:

Indonesian crabs are nocturnal animals. So, there are no special requirements.

Just ensure the output is moderate to avoid overheating the tank and harming your hermits.

Decorations:

Provide as many decorations as you can. Coenobita brevimanus should be able to climb up and down their enclosure.

They will appreciate all types of leaves, wood, plants, PVC pipes, alder cones, and other decorations to enrich their environment. 

Important: Make sure that they are safe as well. For example, avoid using rocks, ceramics, etc. because they can damage themselves if they fall.

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Shell:

Coenobita brevimanus – Detailed Guide Care, Diet, and Breeding - closed in shellShells are crucial for terrestrial hermit crabs. They are in limited supply and indispensable to the basic survival of hermit crabs.

They get empty gastropod shells because they protect their non-calcified abdominal exoskeletons while their mineralized claw is outside the shells. In addition, they can carry water within their shells, and this is used as a reservoir to replace evaporative losses.

Interesting facts:

  • They often locate shells by smell. 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.

Shell preference:

During the process of growth, hermit crabs change shells to suit their body size. Multiple studies have already shown that different species exhibit different preferences for shells and Coenobita brevimanus is not an exception.

In terms of shells, such preferences are a way to prevent and limit competition for resources between different species of hermit crabs.

According to the study, Coenobita brevimanus commonly use:

  • Muricidae Mancinella armigera (22)
  • Turbinidae Turbo (Marmarostoma) argyrostomus (22)
  • Trochidae Tectus niloticus (6)
  • Purpura persica (3)
  • Neritidae Nerita (Linnerita) polita (2)
  • Nerita spp. (2)
  • Pleuroploca trapezium trapezium (2)
  • Bursidae Bursa sp. (1)
  • Thalessa savignyi (1)

In captivity, they may also carry:

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.

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Handling and Bathing Coenobita Brevimanus

You need to handle your hermit crabs with utmost care. They 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.

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.

Despite popular practice, it is not recommended bathing Coenobita brevimanus as well.

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Main Care Rules of Coenobita Brevimanus:

  • 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’). Check it daily.
  • Provide as many décors as you can!
  • Eliminate chlorine and contaminants from the water before usage.
  • Replace the water at least once every 2 – 3 days. Clean their water bowls.
  • Don’t keep only one crab. They are social.
  • Provide various food items to diversify their diet.
  • Remove leftovers daily to avoid mold growth.
  • Replace the substrate bedding at least once every 6 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 Brevimanus 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.
Some people say that Coenobita brevimanus tend to shallow molting and do not dig down deep enough.

This is not true! These hermit crabs prefer to molt underground.

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Breeding Coenobita Brevimanus

I have to start off by saying that due to many different factors, in captivity, the breeding process of Coenobita brevimanus presents various difficulties.

So far, there have been only a few documented reports of successful breeding of this species.

Currently, the pet industry completely depends on wild-caught species. 

Sexing:

Hermit crabs, like other crustaceans, are characterized by sexual dimorphism. Although females are also generally smaller than males of the same age, there are mostly distinguishable by the position of their sexual openings (gonopores).

In Coenobita brevimanus, the gonopores open on the coxae of 3rd pair of pereopods (walking legs) in females, and on the coxae of 5th pair of pereopods in males.

Eggs:

In one of the studies, it was estimated that 39 females released 780,000 zoeae. It means that on average, each female can carry around 20 000 eggs.

The incubation period of Coenobita brevimanus is estimated to be around 1month.

Hatching:

In the wild, Coenobita brevimanus migrate to the ocean to release eggs that hatch into planktonic marine larvae.

Seaward migration of this species shows clear seasonality, they mostly migrate and enter into seawater from July to September when seawater temperature is higher than 77°F (25°C) and ~ 34‰ salinity.

They enter seawater only after sunset between 19:00 to 23:00. Larval release by coenobitid crabs takes place in the swash zone.

Although each female produces thousands of eggs, only a small fraction of them eventually metamorphose and return to the land.

Zoeal duration (Larvae stages):

Coenobita brevimanus – Detailed Guide Care, Diet, and Breeding - larvae stagesAccording to the study, larvae develop through 4 planktonic zoeal stages to a megalopa stage.

It is not certainly known when megalopae migrate ashore, however, they were also recorded migrating onto land by around 16 to 18 days after metamorphosis to the first crab stage.

  Days Size (Total lenght)
Stage 1 3-5 2.7- 2.90
Stage 2 3-5 3.2-3.4
Stage 3 3-5 3.7-4.0
Stage 4 5-7 4.4-4.6
Megalopa 12-20 3.3
First crab stage 23-41 similar between the megalopa and the first crab stage

Interesting fact:

  • Under laboratory conditions, Artemia sp. and the rotifer Brachionus plicatilis are fed to the larvae.
  • Larvae cannot molt at less than 68°F (20°C).
  • Survival rates to metamorphosis into the megalopa stage are high at ~77-77 °F (25–31 °C).
  • Megalopae do not feed for several days before molting into the first crabs.
  • Megalopae start to acquire small shells (4 mm or 0.16 inches) at the ages of 3–4 days. Almost all of them (~90%) carry shells after ~10 days of age.
  • Before molting, only 50% of megalopae and all the first crabs create a small cavity in the sand to hide themselves in for 1–5 days.

Coenobita Brevimanus and Suitable Tankmates

Like most hermit crab species, they are pretty social, gentle, and non-aggressive.

However, they have also been known to prey on smaller species of hermit crabs, such as Coenobita rugosus, making them not only scavengers but also predators.

Moreover, through observation, it was noted that they displayed bubble blowing when preying and feeding on Coenobita rugosus. Whether this behavior is special or occurs occasionally during preying and feeding requires more in-depth research.

At the same time, Coenobita brevimanus can be a great companion for other species. For example, results showed that Strawberry hermit crabs had the highest survival rate (around 83%) when they were mixed with Indonesian hermit crabs.

Coenobita brevimanus can coexist, but with the right species.

Ideally, they should be kept with conspecifics, since it’s unclear if the critter can live peacefully with other terrestrial animals like geckos, lizards, salamanders, newts, etc.

In Conclusion

Coenobita brevimanus are not hard to care for once you understand its need and establish a routine.

As a hermit crab owner, you should always be monitoring the health of your pet and watching out for any indicators of concern because the absolute majority of issues can be traced back to poor care in feeding patterns, humidity, and tank maintenance.

These hermit crabs can be extraordinary companions for many years! However, it also means that you should only acquire these crabs if you are willing to give them special care and attention.

Lastly, instead of supporting the pet industry (remember, they are all wild-caught and heavily exploited as ornamental animals!), you can try to adopt them rather than purchase them.

References:

  1. Lin, Weiqin, Pan Liu, Shan Li, Jie Tian, Wenran Cai, Xiao Zhang, Jinlan Peng et al. “Multi-scale design of the chela of the hermit crab Coenobita brevimanus.” Acta Biomaterialia 127 (2021): 229-241.
  2. Nio, Taketo, Wataru Doi, Akira Mizutani, and Hiroyoshi Kohno. “Seaward migration and larval release of the land hermit crab Coenobita brevimanus Dana, 1852 (Anomura: Coenobitidae) on Iriomote Island, Japan.” Crustacean Research 48 (2019): 67-80.
  3. Hsu, Chia-Hsuan, Marinus L. Otte, Chi-Chang Liu, Jui-Yu Chou, and Wei-Ta Fang. “What are the sympatric mechanisms for three species of terrestrial hermit crab (Coenobita rugosus, C. brevimanus, and C. cavipes) in coastal forests?.” PloS one 13, no. 12 (2018): e0207640.
  4. Hamasaki, Katsuyuki, Saori Kato, Sora Hatta, Yu Murakami, Shigeki Dan, and Shuichi Kitada. “Larval development and emigration behaviour during sea-to-land transition of the land hermit crab Coenobita brevimanus Dana, 1852 (Crustacea: Decapoda: Anomura: Coenobitidae) under laboratory conditions.” Journal of Natural History 48, no. 17-18 (2014): 1061-1084.
  5. Reshmi, R., and A. Bijukumar. “First report of the hermit crabs Coenobita brevimanus and Coenobita rugosus (Crustacea: Decapoda: Anomura) from the Indian coast.” Marine Biodiversity Records 3 (2010).
  6. Doi, Wataru, Hiroyuki Inoue, Akira Mizutani, and Hiroyoshi Kohno. “Gastropod shell use by the land hermit crabs Coenobita brevimanus and C. cavipes in an abandoned village on Iriomotejima Island, Japan.” Crustacean Research 49 (2020): 155-165.
  7. Murakami, Tomokazu, Akira Mizutani, Shinya Shimokawa, and Hiroyoshi Kohno. “Numerical Analysis of the Dynamic State of Coenobita brevimanus Larvae in Amitori Bay.” In Geophysical Approach to Marine Coastal Ecology, pp. 261-273. Springer, Singapore, 2020.
  8. Hamasaki, Katsuyuki, Saori Kato, Yu Murakami, Shigeki Dan, and Shuichi Kitada. “Larval growth, development and duration in terrestrial hermit crabs.” Sexuality and Early Development in Aquatic Organisms 1, no. 2 (2015): 93-107.
  9. Hamasaki, Katsuyuki. “Effect of temperature on larval survival, development and duration of six terrestrial hermit crab species under laboratory conditions.” Aquatic Animals (2020): AA2020-6.
  10. Hemolymph oxygen transport, acid-base status, and hydromineral regulation during dehydration in three terrestrial crabs, Cardisoma, Birgus, and Coenobita. Journal of Experimental Zoology, Volume 218, Issue 1, October 1981, pages 53-64

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