Coenobita rugosus, commonly known as ‘Ruggie, Rug, or Tawny hermit crab’, is a hermit crab species with probably the widest distribution among pet land hermit crabs in the World.
These fascinating small hermit crabs are prized for their cute appearance, attractive colors, and relatively easy maintenance as pets.
Although there are some authoritative sources on its husbandry, I have found that information is often spread over different topics. In addition, in my research about Coenobita rugosus, I have found studies that let us better understand this species and its requirements.
In this detailed guide, I have gathered all information about Coenobita rugosus based on existing studies, research, experiments, and the experience of hermit crab owners. You will know more about these remarkable hermit crabs including their behavior, feeding preferences, ideal tank requirements, and how to take good care of them.
Quick Notes about Coenobita Rugosus
| Name | Ruggie hermit crab |
| Other Names |
Ruggie, Rug, or Tawny hermit crab |
| Scientific Name | Coenobita rugosus |
| Type | Terrestrial |
| Tank size (recommended) | 10 gallons (~40 liters) |
| Keeping | Easy-moderate |
| Breeding | Very Difficult |
| Average size (total length) | up to 3 – 4 inches (7 – 10 cm) |
| Optimal Temperature | 75–82°F (24–28°C) |
| Water type | Freshwater and saltwater bowls |
| Humidity | >80 % |
| Substrate | Sand |
| Diet | Detritivore /omnivore |
| Temperament | Peaceful. Social |
| Life span | 4 – 7 years (in captivity) |
| Color Form | Green, brown, tan, pink, reddish, purple, cream blue, or some other mix of colors |
Etymology of Coenobita Rugosus
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 Rugosus is a Latin adjective for “Wrinkled”, which itself is derived from “Ruga” (“Wrinkle”).
Therefore, Coenobita Rugosus can be translated as ‘Wrinkled Monk’.
Distribution of Coenobita Rugosus
It is believed that Coenobita rugosus originated from Nias Island, Indian Ocean. Nowadays, this species is widely distributed throughout the Indo-Pacific Ocean.
These terrestrial hermit crabs can be found Philippines, Malaisie, Taiwan, Indonésie, China, Japan, Sri Lanka, India, Madagascar, Seychelles (Aldabra Atoll), Christmas Island, the mainland coast of East Africa (Tanzanie, Somalie (Sar Uanle), Kenya, northern Mozambique(Quirirnba Island)), French Polynesia, etc.
Natuarl Habitat of Coenobita Rugosus
Coenobita rugosus has subtropical and tropical distribution. This is a shore dweller species.
These hermit crabs are generally found in the supralittoral zones of sandy beaches and beach forests, though rarely more than about 110 yds (100 m) from high tide.
However, during the rainy season, they were also recorded to go further (up to 220 yds or 200 m).
Description of Coenobita Rugosus
Coenobita rugosus is a relatively small land hermit crab. Fully grown individuals reach up to 1.2 – 1.6 inches (3 – 4 cm) carapace length, 4 – 5 inches (10 – 12 cm) total length, and weigh around 1.7 – 2.4 oz (50 – 70 g). It makes them one of the smallest pet land hermit crabs from the genus Coenobita.
Like most hermit crabs species, Coenobita rugosus does not have complete exoskeletons and uses gastropod shells to protect its soft abdomen. These hermit crabs use chelae as lids for blocking their shells.
Distinguishing characteristics of Coenobita rugosus:
- The left chelae are larger than their right chelae. It is also four-sided.
- The left chelae have seven pronounced striations (stitch marks or ridges). The outer side is darker in color.
- The inner dorsal edge of both chelae bears a brush of bristles.
- The right chelae are almost triangular in shape and quite elongated.
- The carapace has a dark shape that looks like ‘O’.
- The abdomen is short and relatively wide.
- There is a black diagonal behind the base of the antenna.
- The pair of the second antennas are yellow or orange at the base and grey or orange at the tip.
- The eyes are elongated, brown, or even black in color.
- The eyestalks are laterally compressed and non-cylindrical. They are generally yellow-brown or sand-colored. There is a narrowing just in front of the eyes.
- The last pair of walking legs are flattened (resemble a sword) and slender, the color is lighter in the second segment.
Unfortunately, color has never been a good way of determining species. For example, color can vary depending on nutritional intake. Nonetheless, the most common are green, brown, tan, pink, reddish, purple, cream blue, or some other mix of colors that have also been observed in Coenobita rugosus.
Note: Coenobita Rugosus is often mistaken for Coenobita compressus (Ecuadorian hermit crabs) and vice versa because they look almost the same to the untrained eye.
Interesting fact: According to the study, Coenobita rugosus is able to sense water-related odors. They can easily detect the difference between fresh water and seawater and orient themselves appropriately. However, they could barely perceive the odor of coconut.
Lifespan of Coenobita Rugosus
Currently, there is no available data on the longevity of wild individuals. However, scientists assumed that under good conditions Coenobita rugosus can live longer than 10 years.
Although there are some reports that Ruggie Hermit Crabs have been maintained in captivity for more than 15 years, an average lifespan is about 4 – 7 years at most.
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Typical Behavior of Coenobita Rugosus
Coenobita rugosus is a naturally nocturnal terrestrial hermit crab and clearly shows nocturnal habits.
Although they can be still relatively active during the daytime the true pick of their activity starts at dusk and gradually stops before sunrise. This nocturnal behavior is mainly associated with attempting to avoid visual predators, and dehydration when food availability is highest during low tide.
During the day they often hide in crevices or in burrows under debris.
Coenobita rugosus is a moderate burrowing species. In the wild, they generally, burrow to protect against predators and dehydration. They are capable of burrowing under debris, between roots and stones, or in damp sand.
In natural conditions, the Ruggies bury themselves to a variable depth from 1 – 2 inches or 2 – 5 cm (in the sand under the beach waste) to 4 – 6 inches or 10 – 15 cm (in the sand wet by the rain).
Note: They dig with chelipeds which are threaded into the sand practically united, held in front and downwards, and then widened in a movement almost like rowing. The first pair of peraeopods help the action by pushing the sand backward and upwards. The movement is directed more downwards than forwards and the animal sinks almost vertically but in a slightly oblique way.
They are agile and can move quickly. Interestingly, in captivity, hiding is the most preferable behavior followed by burrowing and climbing.
Ruggies are very social hermit crabs. They do not mind staying in high density. The results of the study showed isolation generally decreases their activity levels and increases fear levels, in individuals.
Features:
- Social: Yes
- Active: Yes (once settled)
- Peaceful: Yes
- Burrowers: Yes
Diet of Coenobita Rugosus
Coenobita rugosus is described in the academic literature as feeding generalists and scavengers with a wide dietary intake. In natural conditions, they have generally been found to feed on seeds, fruits, rotting vegetation, animal carcasses, and even animal excretions.
In the wild, as seed dispersers and debris scavengers in coastal forests, they accelerate the decomposition of organic substances.
Even though Coenobita rugosus has poor olfactory capabilities, they are still able to locate food using olfactory antennae (antennules) to capture odors from the surrounding air.
Analysis of their gut content also showed that decomposed leaves and fresh and decomposed flowers were the most common foods eaten by Coenobita rugosus. Therefore, for laboratory experiments, the best feed for hermit crabs was found to be the sequence of apple, followed by jicama, and corn.
Note: This species depends considerably on vegetation in the supralittoral area. It provides shelter, shade, and food.
In captivity, it will be better to provide them with varied, fresh, and low protein content feed.
General recommendations:
The food provided should be with proportion of approximately 10% meat-based diets and 90% vegetables.
Generally, Coenobita rugosus has seemingly unselective food choices. However, hermit crabs may express food preferences on an individual level. In addition, their behavior often switches to unfamiliar food items.
They also require nutrients like calcium, astaxanthin, carotene, and even antioxidants, to be healthy. Therefore, food diversity is crucial.
| 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. |
Coenobita rugosus will readily consume foods like:
- corns,
- carrots (these supply the carotene also needed to maintain their color),
- leafy vegetables,
- oak leaves,
- spinach,
- tree barks,
- nuts and seeds,
- bananas,
- cranberries
- broccoli,
- sweet potatoes,
- red peppers,
- pumpkin,
- squash, etc.
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How Often to Feed Coenobita Rugosus
Adults can be fed 3 – 4 times a week whereas juveniles should be fed daily.
- Leave their food in there for 24 hours before removing it (including fruits and vegetables). Just make sure that whatever they do not consume in one day is removed to prevent moles.
- Obviously, you will have to change it to your livestock’s requirements. It is extremely important to not let Ruggies starve or they can even cannibalize their tank mates.
Keeping and Housing Coenobita Rugosus
The main problem in keeping land hermit crabs in artificial habitats is the mortality rate which is very high. Although Coenobita rugosus does seem to require very little maintenance, they still need a bit more care than you may have been led to believe in pet stores.
To increase their survival rate we need to understand their preferences and mimic their natural habitat. Here are some care guidelines to help you out.
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Tank Size (Enclosure):
In natural conditions, the average density of Coenobita rugosus can be up to 7 crabs per 10 ft2 (or 1 m2).
Although these hermit crabs are relatively small, they do require some space to crawl around. Therefore, the minimum recommended tank size for keeping one Ruggie is a 5-gallon (~20 liters) tank.
Having a larger tank is always preferable. In larger tanks, you will also have more space to allow the addition of suitable environmental enrichment. Therefore, I would say that you need to start with a 10-gallon (or 40 liters) tank.
| Important: Having a smaller tank will significantly limit their freedom. It may also make them more aggressive toward each other. Eventually, lack of space will stress them and reduce their lifespan. |
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Water:
Coenobita rugosus is a fairly euryhaline species. These hermit crabs are able to adapt to a wide range of salinities.
In the wild, Coenobita rugosus have a constant supply of seawater. Therefore, according to the study, in terms of behavior, the majority of Coenobita rugosus prefer gathering around freshwater supply to saltwater supply.
Their water management is based on an equilibrium maintained by, the pressure of constant strong evaporation and a subtle method of uptake from the environment.
In captivity, the presence of both freshwater and saltwater is absolutely necessary to create a favorable environment for these hermit crabs.
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! In the wild, they rarely make contact with the water, except to lay their eggs.
Interesting observations:
- It was recorded that Coenobita rugosus could survive up to 24 hr underwater.
- This species can absorb water from the wet sand with slow movements of the chelipeds and of the third maxillipeds.
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 a very long time.
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 ammonia, nitrites, 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:
Coenobita rugosus crabs 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.
A temperature range between 75 – 82°F (24–28°C) is mostly recommended. They do love warm temperatures.
In natural conditions, Coenobita rugosus never expose themselves to temperatures over 93°F (34°C) as well as the coolest period. To protect themselves they burrowed.
Note: According to the study, many coenobitid juveniles stoped feeding below 64°F (18°C). All Coenobita rugosus had died at the 39°F (4°C) test level. Additionally, all juveniles died on the Boso Peninsula, where the winter temperature was frequently below 50°F (10°C).
Important: It does not mean that the temperature in your crabitat can fluctuate that much in short periods of time! The range of their tolerance is strongly influenced by acclimation temperature. In other words, hermit crabs that are acclimated at lower temperatures can extend their lower temperature tolerance further compared to hermit crabs acclimated to higher temperatures.
| Warning: 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:
Coenobita rugosus 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.
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Substrate:
Coenobita rugosus is a burrowing species. Burrowing space is needed to hide, rest, and protect itself when it is molting. So, the tank should be filled with a substrate into which they can easily burrow.
In nature, Coenobita rugosus is a shore dweller species. They like substrate conditions that are dominated by sandy substrates.
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 (so-called “sandcastle consistency”). However, not so wet that it drips or pools water. Make sure not to waterlog the substrate to avoid the buildup of mold and other parasites.
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).
Note: If we are talking about crabitat that replicates a natural environment – sand is the only option. Nonetheless, we can also use a combination of moist sand and coco fiber (1:5 ratio). It is easy to maintain and it holds moisture very well.
The general rule of thumb is that the substrate needs to be at least twice as deep as your largest crab. If your setup allows it will be better to go for 6 to 8 inches (15 – 20 cm) of the substrate when Ruggies are kept.
They need deep substrate in order to molt properly and to avoid potential aggression during molting from other hermit crabs.
How to Prepare Sand
- Place it into a bucket and spray the sand with a hose.
- The excess water will run out of the bucket and the water will be cloudy and dirty initially.
- Keep rinsing. You will notice that the water will run clearer.
- If you think that sand is clean enough – rinse it again for a few more minutes!
Important:
|
Lighting:
Coenobita rugosus 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 rugosus enjoy hiding, burrowing, and a little bit of climbing.
They will appreciate all types of leaves, wood, plants, PVC pipes, alder cones, and other decorations to enrich their environment.
Important: Make sure that the décor is safe as well. For example, avoid using rocks, ceramics, etc. because hermit crabs can damage themselves if they fall.
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Shells:
Mollusc shells are a vital but also scarce resource for hermit crabs. Shells protect them from mechanical damage and desiccation. Given the scarcity of shells, fighting for them is a common occurrence.
Ideally, the shell should protect the entire body, without any soft tissues exposed. In addition, it should be an appropriate size for hermit crabs to close the opening with their chelae.
Interesting facts:
- Coenobita rugosus are able to 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.
Myth busting: Although shells are vital for hermit crabs, they do not limit their growth. Scientists could not find supporting evidence for that. Their diet plays the most important role.
Shell preference (Shell shop):
Many studies have shown that different species of hermit crabs will exhibit different preferences for shells and suitable opening sizes. It reduces competition for this precious resource.
Regarding shell selection, it was observed that Coenobita rugosus occupied:
- Bursa granularis
- Cerithium caeruleum
- Chicoreus chicoreus
- Fasciola trapezium
- Nassarius arcularius
- Nassanus coronatus
- Natica gualtenana
- Nenta albicilla
- Nerita plicata
- Nerita polita
- Nenta textills
- Peristernia forskali
- Planaxis sulcatus
- Polinices didyma
- Polinices mamilla
- Strombus mutabdis
- Terebralia palustris
- Thais svignyi
- Turbo coronatus
- Volema paradisica
The most used and popular shells are Turbo coronatus, Terebralia palustris, and Nerita plicata.
Coenobita rugosus has a significant preference for squat low-spired shells. Shells with narrow openings are less important, even within their particular size range.
Warning: Do not use glass shells. First, these shells are very heavy for 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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Cleaning:
Keeping crabitat’s cleanliness is important. Remove their feces and food crumbs as often as you can. It will increase their survival rate.
Direct and prolonged contact with its waste and leftovers may lead to dangerous pathogenic agents infecting the organism.
Handling and Bathing Coenobita Rugosus
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 to bathe Coenobita rugosus as well.
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Main Care Rules of Coenobita Rugosus:
- 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 freshwater before usage.
- Replace the water at least once every 2 – 3 days.
- Clean their water bowls and enclosure.
- 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 – 8 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.
- When they are under the substrate, do not dig them up unless you absolutely have to!
Coenobita Rugosus 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.
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Breeding Coenobita Rugosus
Currently, the pet industry completely depends on wild-caught species. There are only a few documented successful attempts to breed them.
A very low success rate is due to high mortality and the insufficient availability of certain environmental stimuli outside of its normal habitat.
Despite their high level of terrestrialization, Coenobita rugosus is still tied to the ocean for reproduction. This species releases marine larvae into the sea to develop. They develop in the ocean through several stages before their metamorphosis into the megalopal stage and then into the juvenile crab (terrestrial form).
Sexing:
Coenobita rugosus is characterized by sexual dimorphism.
- Claws. Left chelae are larger in males (for the first time in terrestrial hermit crabs).
- Genitals. Males and females are clearly distinguishable by the position of their sexual openings (gonopores). The gonopores open typically on the coxae of 3rd pair of pereopods (walking legs) in females, and on the coxae of 5th pair of pereopods in males.
Note: According to the study, the external reproductive organs and the secondary sexual characters of both sexes complete when their carapace length reaches 0.24 inches (6 mm). And it has been found that a female with 0.31 inches (8 mm) carapace length was already incubating.
Eggs:
There is a positive correlation between the size of females and the number of eggs as larger females produce more eggs.
The eggs are almost uniform in size. They are oval in shape and measure 0.73 mm x 0.56 mm. The eggs have a reddish brown color, glassy, and are covered by a double thin membrane that is strong and transparent.
Females retain eggs throughout their entire development. Presumably, the eggs are fertilized by means of the spermatophore soon after being laid.
Females carry the eggs for about a month. They are hidden in her shell.
Hatching:
Coenobita rugosus has 5 zoeal (larvae) stages. The zoea-egg hatches out almost immediately at a stimulus exerted by seawater, and the zoea becomes free. It generally swims in a heads-down position.
| Stages | Average total length (mm) |
| Stage 1 | 2.59 |
| Stage 2 | 3.10 |
| Stage 3 | 4.23 |
| Stage 4 | 4.48 |
| Stage 5 | 4.85 |
| Megalopal stage | 4.00 |
Early megalopae of the terrestrial hermit crabs are active swimmers, which is likely associated with their immigration behavior to inshore habitats where they settle.
Some additional information:
- The size (carapace length) of the smallest ovigerous female was 3.93 mm for Coenobita
- Larvae cannot survive to the megalopal stage at temperatures below 68°F (20°С).
- Megalopae only appeared at temperatures above 71°F (22°C). Its survival rate is optimal at 77 – 88°F (25–31°C) and declines over ~ 90°F (32°C).
- Larvae of Coenobita rugosus require approximately 30–40 days before migrating onto shores as megalopae carrying gastropod shells.
- It takes another 5 – 6 days for the megalopae to metamorphose into the first crab stage.
- Coenobita rugosus has fully developed oocytes from May to October. Some females may produce at least two broods during the breeding season.
- Although larvae can tolerate from 34 ppt to 20 ppt salinity conditions, low-salinity seawater tends to enhance the molting and survival rates of hermit crabs. Also, sudden changes in salinity conditions will cause mortality.
- The experiment demonstrated that low salinity decreased the swimming activity and enhanced the walking activity at the bottom, i.e., the conditions stimulated the settlement behavior of megalopae.
Coenobita Rugosus and Suitable Tankmates
Like many hermit crab species, Ruggies are pretty social, gentle, and non-aggressive.
In their natural habitat, they have also been preyed on by bigger crabs such as Indonesian crabs (Coenobita brevimanus).
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
Although Coenobita rugosus does seem to require little care, it is not completely so. In captivity, their habitat should be representative of their natural habitat and their diet should be diverse as well.
Provide them with burrowing, climbing, and hiding space, it will make them more active.
These hermit crabs are very cute and can be amazing companions for many years! However, it also means that you should only acquire them if you are willing to give them the special care and attention they need.
References:
- 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 one13, no. 12 (2018): e0207640.
- Hsu, Chia-Hsuan, and Keryea Soong. “Mechanisms causing size differences of the land hermit crab Coenobita rugosus among eco-islands in Southern Taiwan.” PloS one12, no. 4 (2017): e0174319.
- Bundhitwongrut, Thanakhom, Kumthorn Thirakhupt, and Art-ong Pradatsundarasar. “Population ecology of the land hermit crab Coenobita rugosus (Anomura, Coenobitidae) at Cape Panwa, Phuket island, Andaman coast of Thailand.” Natural History Bulletin of the Siam Society60 (2014): 31-51.
- Fujikawa, Shunsuke, Katsuyuki Hamasaki, Shigeki Dan, and Shuichi Kitada. “Emigration behaviour, moulting and survival during the sea-to-land transition of land hermit crabs Coenobita violascens and Coenobita rugosus under laboratory conditions: effects of salinity and riverine odours.” Biogeography20 (2018): 111-121.
- Vannini, Marco. “RESEARCHES ON THE COAST OF SOMALIA. THE SHORE AND THE DUNE OF SAR UANLE: 7. FIELD OBSERVATIONS ON THE PERIODICAL TRANSDUNAL MIGRATIONS OF THE HERMIT CRAB COENOBITA RUGOSUS MILNE EDWARDS: PUBBLICAZIONI DEL CENTRO DI STUDIO PER LA FAUNISTICA ED ECOLOGIA TROPICALI DEL CNR: CVI.” Monitore Zoologico Italiano. Supplemento7, no. 1 (1976): 145-185.
- Vannini, Marco. “RESEARCHES ON THE COAST OF SOMALIA. THE SHORE AND THE DUNE OF SAR UANLE: 5. DESCRIPTION AND RHYTHMICITY OF DIGGING BEHAVIOUR IN COENOBITA RUGOSUS MILNE EDWARDS: PUBBLICAZIONI DEL CENTRO DI STUDIO PER LA FAUNISTICA ED ECOLOGIA TROPICALI DEL CNR: XCVII.” Monitore Zoologico Italiano. Supplemento6, no. 1 (1975): 233-242.
- Hutagalung, R. A., N. W. Koswara, and V. D. Prasasty. “Improving the survival rate of land hermit crabs (Coenobita rugosus) through artificial habitat design.” In IOP Conference Series: Earth and Environmental Science, vol. 278, no. 1, p. 012036. IOP Publishing, 2019.
- Nakasone, Yukio. “Reproductive biology of three land hermit crabs (Decapoda: Anomura: Coenobitidae) in Okinawa, Japan.” Pacific Science55, no. 2 (2001): 157-169.
- Bartmess-LeVasseur, Julia N., and Todd M. Freeberg. “Isolation increases time to emerge from shells in two Coenobita hermit crab species.” acta ethologica18, no. 2 (2015): 221-225.
- Vannini, Marco, and Jacopo Ferretti. “Chemoreception in two species of terrestrial hermit crabs (Decapoda: Coenobitidae).” Journal of Crustacean Biology17, no. 1 (1997): 33-37.
- Barnes, David KA. “Ecology of tropical hermit crabs at Quirimba Island, Mozambique: shell characteristics and utilisation.” Marine Ecology Progress Series183 (1999): 241-251.
- Hutagalung, Rory Anthony, Stella Magdalena, Isdaryanto Iskandar, and Sylvain Mastrorillo. “Increasing growth and survival rate of land hermit crabs (Coenobita sp.) in artificial habitat through feeding habit.” International Journal of Applied and Physical Sciences3, no. 3 (2017): 55-59.
- Hamasaki, Katsuyuki. “Effect of temperature on larval survival, development and duration of six terrestrial hermit crab species under laboratory conditions.” Aquatic Animals(2020):
- https://coenobitaspecies.com/coenobitidae-family/
- https://tonycoenobita.com/coenobita_rugosus_eng.htm
- http://decapoda.free.fr/illustration.php?n=6&sp=187
- https://hermitcrabassociation.com/
Hi Michael,
I’m getting into my first terrarium and was looking into the ruggies as a good fit. I have a 110 L tank and you say they require 40L. My question though is how many i could put in this tank safely? I don’t want to cramp their living space but I don’t want them to become lonely either. What’s your two cents?
cheers.
Hi David Kerkhove,
Of course, it depends on the size of your hermit crabs. If we are talking about adult individuals, I would say that you can keep 3 crabs in your terrarium. In theory, you can have more, but if you want each of them to have the opportunity to spend some time in relative solitude and prevent them from constantly digging each other up, I would still recommend sticking to three or a maximum of four.
Best regards,
Michael
Hi Michael, me again!
Thanks for the advice last time,
I have set up my tank and all the parameters are fine for the crabs so i was planning on actually getting them soon. I came upon two more issues though.
Looking at the preffered shell list i have found some Turbo Stenogyrus and Nérita plicata shells, ranging from 1 to 4~ centimeter (height). I’m planning on getting a few juiveniles (6 months) and i was wondering how big the shells theyll need through their entire life should be. Buying all the shells in one go seems most economic with shipping and all. It seems these shells dont get any larger than the 1-4 cm range so if the crabs were to outgrow them (will they?) should i be looking at different shells? Or is it ok if i buy 20 shells per crab along this entire range?
my second question is more of a logistics one, I’m based in the Netherlands and all the food pellets that were linked as fit for hermit crabs were unavailable on both the sites and anywhere i looked online. What is a good (still available) alternative in your opinion? I’ll be mixing it with fresh fruits and vegetables of course but some of the nutrients they need are easier using them.
Thanks for reading,
cheers,
David.
Hi David,
It’s great that you’re considering the appropriate shells for your hermit crabs beforehand! When it comes to choosing shells for hermit crabs, it’s a good idea to follow a general rule of thumb: the shell should be about 1.5 or 2 times (max) the size of the crab’s current shell. This provides them with room to grow comfortably.
While having a variety of shells within the 1-4 cm range is beneficial, it’s also a good idea to have a few larger shells available in case your crabs exceed these sizes. Sometimes, individual crabs might have slightly different growth rates, and they might need larger shells than the average size for their species. Additionally, I would not worry or focus only on Turbo Stenogyrus and Nérita plicata. Sure these shells are good for this species, but it does not mean that they are irreplacable. Anyway, buying shells in bulk can be cost-effective.
As for the second part of the question.
The article contains a link to an article about the diet of hermit crabs and what we can feed them besides specialized crab food.
There’s one subtle point here – specialized foods are beneficial and convenient for us, but at the same time, their importance shouldn’t be exaggerated. In the wild, these crabs are scavengers and eat almost anything they can find.
So, if you’re unable to purchase specialized crab food, simply try to diversify their diet as much as possible. As mentioned in the article, there are extensive lists of what hermit crabs like and what to avoid when feeding them.
When you feed them, you’ll quickly notice their preferences 🙂
Best regards,
Michael