Hermit Crab Shell Selection: How to Choose and Prepare Shells for Your Pet

Hermit crabs depend on gastropod shells for protection, moisture retention, and defense against predators. Selecting and preparing appropriate shells is a core husbandry task for owners of terrestrial and marine hermit crabs. This article explains how to assess shell type, size, condition, and preparation methods, and what to do when a crab is shell-less. The guidance is based on published research on shell selection behavior and is intended for pet owners, veterinary students, veterinary technicians, and veterinary professionals who advise on invertebrate care.

At a Glance: Shell Selection Decision Table

Understanding Hermit Crab Shell Needs

Hermit crabs are crustaceans that carry an empty gastropod shell as a portable refuge. The shell protects the soft abdomen from predators, desiccation, and physical damage. Shell availability is a limiting resource for many hermit crab populations, and crabs actively assess and compete for suitable shells. Research on the terrestrial hermit crab Coenobita compressus shows that shell size, shell species, and shell condition are the three major variables that influence shell utilization and selection. In the field, crabs are often found in shells smaller than their preferred size, and this difference is most pronounced in relatively small individuals. Shell size preference also differs between crabs collected at different sites, indicating that local shell supply shapes what crabs accept.

For pet owners, this means that offering a range of shell sizes and types is essential. A crab that appears healthy but refuses available shells may be rejecting them because none match its preferred size or species. The same research found that Coenobita compressus prefers shells that have been previously used by other hermit crabs, likely because the crabs modify the shell interior, increasing the effective internal volume. This finding supports the practice of offering shells that have been occupied before, provided they are cleaned and free of debris.

The relationship between crab size and shell preference is dynamic. Research on Calcinus californiensis demonstrates that as crabs grow, they shift from assigning similar value to several shell species to exhibiting a strong preference for conical shells. This shift occurs because shell traits change allometrically with size. Conical shells gain mass at a higher rate than globose shells relative to their internal volume, so small crabs carry similar shell mass in both types while larger individuals must carry much heavier conical shells to obtain the same internal volume as globose shells. Owners should therefore adjust shell offerings as their crab grows, recognizing that a shell type once rejected may become preferred at a larger body size.

Shell Types and Species Preferences

Different hermit crab species have evolved preferences for distinct shell morphologies. A study of two co-occurring terrestrial species, Coenobita rugosus and Coenobita perlatus, found that each species utilizes a distinct subset of the available shell resource. Coenobita rugosus prefers a short and globose shell morphology, while Coenobita perlatus prefers an elongated shell with a narrow aperture. These preferences arise from intrinsic differences between the species and allow them to coexist in the same habitat by partitioning the shell resource.

For owners, this means that the species of your hermit crab determines which shell types are most likely to be accepted. Common pet species include Coenobita clypeatus (Caribbean hermit crab), Coenobita compressus (Ecuadorian hermit crab), and various marine species such as Pagurus and Clibanarius. Research on Coenobita species in the Andaman and Nicobar Islands shows that Coenobita rugosus occupies shells from multiple gastropod families, including Turbinidae, Muricidae, Trochidae, Strombidae, Buccinidae, Neritidae, Cerithidae, Cymatidae, Olividae, and even plastic debris such as bottle caps. In contrast, Coenobita violascens prefers shells of Turbinidae and Muricidae, while Coenobita brevimanus selects only Turbinidae shells.

Practical guidance for owners is to offer a variety of shell types and observe which ones the crab investigates, turns, and enters. Marine species such as Pagurus bernhardus show preferences for darker shells over white shells, and this preference is influenced by background color. A study on Pagurus bernhardus found that crabs prefer black shells over white, but this preference disappears when visual cues are absent. The same study showed that crabs prefer darker red shells over yellow shells, suggesting that shell color and shading matter to some species. Offering shells in a range of colors and shades may improve acceptance rates.

The shell species available in the pet trade varies by region and supplier. Common offerings include turbo shells, magpie shells, tapestry shells, and various cone shells. For marine hermit crabs, the range of acceptable shell species may be broader, but species-specific preferences still apply. Owners should research the natural shell preferences of their crab species and prioritize those shell types in their offerings.

Shell Sizing: How to Measure and Match

Shell size is the most critical factor in shell selection. A shell that is too small does not accommodate the crab's abdomen, while a shell that is too large is heavy and difficult to carry. Research on Calcinus californiensis shows that shell traits change allometrically with size. Conical shells gain mass at a higher rate than globose shells relative to their internal volume. Small crabs carry similar shell mass in both shell types, but larger individuals must carry much heavier conical shells to obtain the same internal volume as globose shells. This means that the optimal shell type changes as the crab grows, and owners should adjust the shell offerings accordingly.

To size a shell for a hermit crab, measure the crab's shield length, which is the hard anterior portion of the cephalothorax. The aperture width of the shell should be slightly larger than the crab's largest chela, allowing the crab to withdraw fully and seal the opening with its claw. A shell that is too small forces the crab to protrude, increasing the risk of predation and desiccation. A shell that is too large is difficult to maneuver and may cause the crab to abandon it.

A practical method for sizing is to offer several shells with progressively larger aperture widths and observe which shell the crab chooses. Hermit crabs investigate shells by inserting their chelae and walking around the shell, assessing internal volume and weight. A crab that repeatedly tries a shell and then moves on is signaling that the shell is not suitable. Owners should provide at least two to three shells per crab, with sizes ranging from slightly smaller to slightly larger than the current shell.

Temperature and salinity also affect shell size preference. Research on the marine hermit crab Pagurus longicarpus found that increasing water temperature from 22 °C to 32 °C significantly affects the size of shells chosen, as does lowering the temperature to 16 °C. Reducing salinity from 30 ppt to 15 ppt also affects shell choice. For marine hermit crab owners, this means that water temperature and salinity should be stable before offering new shells, because crabs in stressful conditions may accept suboptimal shells or reject suitable ones.

Shell Sizing Reference Table

Shell Preparation and Cleaning

Preparing shells before offering them to a hermit crab is essential for hygiene and acceptance. Shells collected from beaches or purchased from pet stores may contain organic material, debris, or residues that deter crabs or introduce pathogens. The preparation process involves cleaning, sterilizing, and drying.

Boiling is a common method for sterilizing shells. Place the shells in boiling water for 10 to 15 minutes, then allow them to cool completely. Do not use soap or detergent, as residues can be toxic to crabs. After boiling, scrub the shells with a soft brush to remove any remaining organic material. Rinse thoroughly in fresh water or saltwater, depending on whether the crab is terrestrial or marine. Allow the shells to air dry completely before offering them to the crab.

An alternative method is soaking shells in saltwater for 24 to 48 hours. This is suitable for marine hermit crabs and helps remove organic material without the risk of thermal damage. For terrestrial crabs, a saltwater soak followed by a fresh water rinse and air drying works well. Avoid using bleach, alcohol, or other chemical disinfectants, as these can leave toxic residues.

Shells that have been previously occupied by other hermit crabs are often preferred, as noted in the research on Coenobita compressus. However, these shells must be cleaned thoroughly to remove any remaining tissue or waste. Inspect the interior of each shell for debris, mold, or foul odor. Discard shells with cracks, chips, or sharp edges, as these can injure the crab's abdomen.

The preparation method should match the shell material. Thin-shelled species may crack during boiling, while thick-shelled species tolerate boiling well. For delicate shells, the saltwater soak method is gentler. Owners should inspect shells after preparation for any damage that may have occurred during cleaning.

Shell Abandonment: Causes and First Response

A hermit crab that is outside its shell is in a vulnerable state. The abdomen is soft and unprotected, and the crab is at high risk of desiccation, injury, and stress. Shell abandonment can occur for several reasons, including unsuitable shell size or type, poor environmental conditions, stress, illness, or exposure to toxins.

Research on shell removal techniques provides insight into how crabs respond to forced shell abandonment. A study comparing heating the shell apex and cracking the shell found that both methods are stressful, but the effects differ. Crabs removed via heating increased their respiratory rate shortly after manipulation and recovered their metabolic rate in less than 24 hours. Crabs removed via cracking spent more time hiding in their new shells, and this effect lasted more than 24 hours, similar to responses after a predator attack. This research is relevant to owners who may need to remove a crab from its shell for inspection, and it suggests that heating is less invasive than cracking for tropical species.

If you find a hermit crab outside its shell, the first response is to isolate it in a small, humid container. Provide a shallow dish of fresh or saltwater, depending on the species, and place several prepared shells of appropriate size in the container. Keep the container in a quiet, dimly lit area to reduce stress. Monitor the crab closely for signs of improvement, such as investigating and entering a shell.

If the crab does not enter a shell within a few hours, assess the environmental conditions. Check temperature and humidity, as both affect shell selection behavior. Research on Pagurus longicarpus shows that temperature changes affect shell size preference, and extreme conditions may cause crabs to reject shells. For terrestrial crabs, humidity should be high, typically above 70 percent, to prevent desiccation. For marine crabs, water temperature and salinity should be within the species-specific range.

Shell Abandonment Decision Checklist

Environmental Factors That Affect Shell Selection

Environmental conditions influence whether a crab accepts a shell and which shell it chooses. Hypoxia, or low oxygen levels, affects shell assessment and selection in hermit crabs. Research on this topic shows that crabs in hypoxic conditions are less choosy or have different preferences compared to crabs in normoxic conditions. For owners, this means that poor water quality or inadequate ventilation in a terrestrial enclosure can reduce a crab's ability to assess shells properly.

Microplastic pollution is another environmental factor that affects shell selection behavior. A study on the common European hermit crab Pagurus bernhardus found that crabs exposed to polyethylene microplastic spheres for five days were less likely to contact or enter optimal shells compared to control crabs. The exposed crabs also took longer to contact and enter the optimal shell. These results indicate that microplastics impair cognition, disrupting an essential survival behavior. A follow-up study found sex-dependent effects, with plastic-exposed females more likely to select the high-quality shell than control females, while control females spent longer investigating the high-quality shell compared to males.

For pet owners, this research highlights the importance of water quality and substrate cleanliness. Microplastics can enter enclosures through contaminated water, substrate, or food. Using filtered water, cleaning substrate regularly, and avoiding plastic decorations that can degrade may reduce the risk of microplastic exposure. While the research was conducted on marine crabs, the findings suggest that environmental pollutants can affect shell selection behavior in any hermit crab species.

Research on microplastic accumulation in hermit crabs from the Sundarban Biosphere Reserve found microplastics in the gills and gut of Clibanarius longitarsus, as well as in the water present in its occupied gastropod shell. The study documented that shell water exhibited accumulation of microplastics, with green and black as the preferable microplastics for the crab. This finding is directly relevant to pet owners because it demonstrates that the water inside a crab's shell can harbor contaminants. Regular water changes and filtration are important for maintaining shell water quality.

Toxic algae also affect shell selection. Research on the impacts of the toxic red tide algae Karenia brevis on shell selection behavior in Pagurus longicarpus shows that exposure to this toxin alters shell assessment. For marine hermit crab owners, this means that water from natural sources should be tested for algal toxins before use. If a crab shows abnormal shell selection behavior, consider whether the water source may be contaminated.

Shell Competition and Social Dynamics

Hermit crabs are social animals that interact with each other, and shell competition is a natural part of their behavior. Research on shell-selection behavior in Pagurus granosimanus in relation to isolation, competition, and predation shows that the presence of other crabs affects shell choice. Crabs that are isolated may accept shells they would reject in the presence of competitors, while crabs in competitive situations may make different choices.

For owners with multiple crabs, this means that shell availability must be sufficient to prevent harmful competition. Provide at least two to three shells per crab, with a range of sizes and types. Observe the group for signs of shell fighting, where one crab attempts to pull another from its shell. This behavior is stressful and can cause injury. If shell fighting occurs, separate the crabs and provide additional shells.

Research on shell resource partitioning in terrestrial hermit crabs shows that different species prefer different shell morphologies, which allows coexistence. In a mixed-species enclosure, offering a variety of shell types can reduce competition. However, owners should be aware that some species may not coexist peacefully, and separate enclosures may be necessary.

Predation threat also influences shell selection. Research on Pagurus longicarpus shows that crabs under predation threat make different shell choices compared to crabs in safe conditions. Crabs may prioritize shells that offer better protection over shells that are more comfortable or easier to carry. For owners, this means that a crab that has recently experienced a stressful event, such as handling or a predator encounter, may reject shells it would otherwise accept.

The structure of the shell itself can influence social interactions. Research on shell structure in agonistic interactions shows that shell characteristics can provide advantages to owners but not to intruders during conflicts. This means that a crab in a well-fitted, high-quality shell may be better able to defend its shell against competitors. Providing high-quality shells to all crabs in a group can reduce the frequency and intensity of shell fights.

Shell Quality and Condition Assessment

Shell condition is a major factor in shell selection. Research on Coenobita compressus identified shell condition as one of the three major variables affecting shell utilization. Crabs prefer shells that are intact, free of cracks, and have a smooth interior. Shells with chips, cracks, or rough edges can injure the crab's abdomen and are often rejected.

When assessing shell quality, inspect the following:

• Exterior surface for cracks, chips, or holes
• Interior for debris, mold, or foul odor
• Aperture edge for sharp or jagged areas
• Overall structural integrity, including the spire and columella

Discard any shell that shows signs of damage. A cracked shell may break further while the crab is carrying it, exposing the abdomen to predators and desiccation. A shell with a sharp aperture edge can cut the crab's soft abdomen, leading to infection.

Shell modification by previous occupants can improve shell quality. Research on Coenobita compressus found that crabs modify shells by removing material from the interior, increasing the effective size. This modification makes previously occupied shells more desirable. For owners, this means that shells that have been used by other crabs may be more attractive to a new crab, provided they are cleaned and structurally sound.

The weight of a shell relative to its internal volume is an important quality factor. Research on Calcinus californiensis shows that conical shells gain mass at a higher rate than globose shells relative to internal volume as they increase in size. This means that for larger crabs, a globose shell may offer the same internal volume at a lower carrying cost. Owners should consider shell weight when selecting offerings for larger crabs.

Practical Workflow for Introducing New Shells

Introducing new shells to a hermit crab enclosure requires a systematic approach. Follow these steps to maximize the chance of acceptance:

1. Prepare the shells by boiling or soaking, scrubbing, rinsing, and drying completely.
2. Measure the crab's shield length and largest chela to determine the appropriate aperture width range.
3. Select shells with aperture widths ranging from slightly smaller to slightly larger than the current shell.
4. Place the prepared shells in the enclosure, preferably near the crab's favorite hiding spot or food dish.
5. Observe the crab's behavior over the next 24 to 48 hours. A crab that is interested in a shell will approach it, insert its chelae, and turn the shell to assess its weight and volume.
6. If the crab does not investigate the shells within 48 hours, try different shell types, sizes, or colors.
7. Record which shells the crab accepts and rejects to build a preference profile.

For crabs that are shell-less, the workflow is more urgent. Isolate the crab in a small, humid container with several prepared shells. Provide a shallow water dish and a moist substrate. Monitor the crab closely and escalate to a veterinarian if the crab does not enter a shell within 24 hours or shows signs of distress, such as lethargy, discoloration, or inability to right itself.

The timing of shell introduction matters. Research on Pagurus bernhardus shows that crabs use visual cues during shell selection, and the strength of preference depends on background color. Placing shells against a contrasting background may make them more visible and attractive to the crab. Owners can experiment with shell placement to determine what works best for their individual crab.

Records and Measurements

Keeping records of shell selection behavior helps owners identify patterns and make informed decisions. Record the following for each crab:

• Species and approximate age
• Shield length and chela width measurements
• Current shell species, size, and condition
• Date of shell change
• Shells offered and whether each was accepted or rejected
• Environmental conditions at the time of shell introduction, including temperature and humidity for terrestrial crabs or temperature and salinity for marine crabs

These records are valuable for veterinary consultations. If a crab repeatedly rejects shells or shows abnormal shell selection behavior, the records can help the veterinarian identify potential causes, such as environmental stress, illness, or toxin exposure.

For veterinary professionals, morphometric measurements are useful for species identification and health assessment. Research on Coenobita species in the Andaman and Nicobar Islands identified shield length, cheliped propodus length, and cheliped dactylus length as important parameters for species differentiation. These measurements can be taken with a vernier caliper and recorded in the patient file.

Morphometric data also support species identification when color patterns are absent. The same research found that one-way ANOVA showed significant differences in shield length values among the three species studied, and mean shield length values varied significantly between males and females for some species. Veterinary professionals can use these measurements to confirm species identification, which informs appropriate shell offerings and environmental parameters.

Common Failure Patterns in Shell Selection

Owners may encounter several common problems when offering shells to hermit crabs. Understanding these patterns helps in troubleshooting.

Crab ignores all offered shells. This pattern suggests that the shells do not match the crab's preferences. The shells may be the wrong size, type, or color. Review the crab's species and size, and offer a wider variety of shells. Environmental stress, such as low humidity or poor water quality, can also reduce shell investigation behavior.

Crab investigates shells but does not enter. This pattern indicates that the crab is interested but finds the shells unsuitable. The shells may be too heavy, too large, or have an internal obstruction. Check the interior of each shell for debris or irregularities. Offer lighter shells or shells with a larger internal volume relative to their weight.

Crab enters a shell but abandons it within hours. This pattern suggests that the shell is uncomfortable or the crab is stressed. The shell may be too small, causing the crab to protrude, or too large, making it difficult to carry. Environmental conditions, such as temperature or humidity fluctuations, can also cause abandonment.

Crab repeatedly switches shells. This pattern is common in social groups where shell competition occurs. The crab may be trying to find a better shell or may be displaced by a larger crab. Provide additional shells and observe for shell fighting.

Crab remains shell-less despite multiple offerings. This is an emergency situation. The crab is at high risk of desiccation and injury. Isolate the crab, provide a humid environment, and offer a variety of prepared shells. If the crab does not enter a shell within 24 hours, escalate to a veterinarian.

Crab selects a shell that appears too large or too small. This pattern may reflect species-specific preferences or environmental stress. Research on Pagurus longicarpus shows that temperature and salinity changes affect the sizes of shells chosen. If a crab selects an unusual shell size, check environmental parameters and compare with the crab's normal behavior.

Welfare and Safety Considerations

Hermit crab welfare depends on appropriate shell provision, environmental conditions, and handling practices. Forced shell removal is sometimes necessary for health assessment, but it is stressful for the crab. Research comparing heating and cracking methods found that both are stressful, harmful, or fear-inducing. However, heating the shell apex is less invasive than cracking for tropical species, because the temperature required to force abandonment is below the critical thermal maximum of most tropical tide pool inhabitants, and the metabolic effects resolve within 24 hours. Cracking causes a longer-lasting behavioral response, similar to a predator attack.

For owners, this means that shell removal should be avoided unless absolutely necessary. If a crab must be removed from its shell for veterinary examination, heating the shell apex is the preferred method for tropical species. The crab should be monitored closely after removal and provided with a suitable replacement shell immediately.

Safety considerations also apply to shell preparation. Boiling shells can cause burns, and owners should use tongs and allow shells to cool completely before handling. Do not use chemical disinfectants, as residues can be toxic to crabs. When collecting shells from the wild, be aware of local regulations regarding shell collection and avoid taking shells that are occupied by living gastropods.

Plastic debris poses a specific welfare risk to hermit crabs. Research from the Nicobar Islands documented 4783 entrapments of hermit crabs in marine litter, with 4102 crabs trapped in 198 plastic and glass bottles. Only 0.52 percent of entrapped hermit crabs were found alive. The bottle opening diameter acts as a size-selective filter, allowing entry of hermit crabs whose shell widths are smaller than the opening. This research underscores the importance of never offering plastic containers or bottle caps as shell substitutes, even though some wild crabs have been observed occupying them. The entrapment risk is severe and often fatal.

Professional Escalation Criteria

Veterinary professionals should be consulted in the following situations:

• A hermit crab remains shell-less for more than 24 hours despite appropriate shell offerings and environmental conditions
• A hermit crab shows signs of injury, such as bleeding, discoloration, or a damaged abdomen
• A hermit crab is lethargic, unresponsive, or unable to right itself
• A hermit crab has been exposed to toxins, such as microplastics, algal toxins, or chemical residues
• A hermit crab shows abnormal shell selection behavior that persists for more than one week

Veterinary professionals should assess the crab's overall health, including hydration status, body condition, and evidence of infection or parasitism. They should also review the owner's records of shell offerings, environmental conditions, and behavior. Treatment may include fluid therapy, nutritional support, and environmental modification. Drug doses and withdrawal periods are not provided in this article, and veterinary professionals should consult current formularies and regulations for any pharmacological treatment.

The World Organisation for Animal Health provides standards for animal health and welfare that may inform veterinary practice with invertebrates. While specific guidance for hermit crabs is limited, the general principles of minimizing stress, providing appropriate environmental conditions, and avoiding unnecessary harm apply. Veterinary professionals should stay informed of current welfare standards and incorporate them into their recommendations for invertebrate patients.

The Merck Veterinary Manual serves as a reference for veterinary professionals managing unusual or exotic species. While hermit crab coverage may be limited, the manual provides guidance on general crustacean care and disease recognition that can support clinical decision-making.

Frequently Asked Questions

What size shell should I offer my hermit crab?

Measure the crab's shield length and the width of its largest chela. The shell aperture should be slightly larger than the chela, allowing the crab to withdraw fully and seal the opening. Offer several shells with progressively larger apertures and observe which one the crab accepts. Research on Coenobita compressus shows that crabs in the field often occupy shells smaller than their preferred size, so a crab may accept a shell that appears slightly small.

How do I clean shells before giving them to my hermit crab?

Boil the shells in water for 10 to 15 minutes, then allow them to cool completely. Scrub with a soft brush to remove organic material, rinse thoroughly, and air dry completely. Do not use soap, detergent, bleach, or alcohol, as residues can be toxic. For marine crabs, a saltwater soak for 24 to 48 hours is an alternative to boiling.

Why is my hermit crab not entering any of the shells I offered?

The shells may not match the crab's species-specific preferences for size, type, or color. Review the crab's species and offer a wider variety of shells. Environmental stress, such as low humidity, poor water quality, or temperature fluctuations, can also reduce shell investigation behavior. Research on Pagurus bernhardus shows that crabs prefer darker shells, and this preference is influenced by background color.

What should I do if my hermit crab is out of its shell?

Isolate the crab in a small, humid container with several prepared shells of appropriate size. Provide a shallow water dish and a moist substrate. Keep the container in a quiet, dimly lit area. Monitor the crab closely. If it does not enter a shell within 24 hours or shows signs of distress, consult a veterinarian.

Can I force my hermit crab out of its shell for inspection?

Forced shell removal is stressful and should be avoided unless necessary. Research comparing heating and cracking methods found that heating the shell apex is less invasive for tropical species, with metabolic effects resolving within 24 hours. Cracking causes a longer-lasting behavioral response. If removal is necessary, use the heating method and provide a replacement shell immediately.

Do hermit crabs prefer certain shell colors?

Some species show color preferences. Research on Pagurus bernhardus found that crabs prefer black shells over white and darker red shells over yellow. This preference is influenced by background color and may be rooted in a preference for darker shaded shells. Offering shells in a range of colors may improve acceptance rates.

How many shells should I provide for multiple hermit crabs?

Provide at least two to three shells per crab, with a range of sizes and types. Shell competition is natural, and insufficient shell availability can lead to shell fighting and stress. Research on shell resource partitioning shows that different species prefer different shell morphologies, so offering a variety of shell types can reduce competition in mixed-species enclosures.

Can microplastics affect my hermit crab's shell selection?

Research on Pagurus bernhardus found that crabs exposed to polyethylene microplastic spheres for five days were less likely to contact or enter optimal shells and took longer to do so. Microplastics can enter enclosures through contaminated water, substrate, or food. Use filtered water, clean substrate regularly, and avoid plastic decorations that can degrade to reduce exposure risk.

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References and Further Reading

• Merck Veterinary Manual. Merck Veterinary Manual.
• Animal Health and Welfare. World Organisation for Animal Health.
• Microplastics disrupt hermit crab shell selection.. Biology letters, 2020.
• Does microplastic exposure and sex influence shell selection and motivation in the common European hermit crab, Pagurus bernhardus?. The Science of the total environment, 2023.
• Shell selection and utilization in a terrestrial hermit crab, Coenobita compressus (H. Milne Edwards).. Oecologia, 1978.
• Context-dependent use of visual cues in the shell selection behaviour of the hermit crab Pagurus bernhardus.. Behavioural processes, 2021.
• Shell resource partitioning as a mechanism of coexistence in two co-occurring terrestrial hermit crab species.. BMC ecology, 2020.
• Characterization and ecological risk assessment of microplastics accumulated in sea water, sand, sediment, shell water and selected tissues of hermit crab of Sundarban Biosphere Reserve.. Environmental pollution (Barking, Essex : 1987), 2024.
• Temperature and Salinity Effects on Shell Selection by the Hermit Crab Pagurus longicarpus.. The Biological bulletin, 2018.
• Can morphometrics and shell preference behaviour be a tool for hermit crab species identification?. Marine environmental research, 2025.
• Allometric shell scaling drives body size-dependent shifts in preference and performance in a hermit crab.. 2026.
• Size-specific vulnerability of hermit crab (Coenobita spp.) to entrapment in marine plastic litter: Evidence from the Nicobar Islands, India.. 2026.
• Designation of a Brazilian topotypic neotype for Dardanus pectinatus (Ortmann, 1892) and establishment of D. ctenodon sp. nov. for the East Atlantic hermit crab previously misidentified with it (Crustacea, Decapoda, Anomura, Diogenidae).. 2025.
• Metabolic and behavioural effects of hermit crab shell removal techniques: Is heating less invasive than cracking?. Animal Welfare, 2023.
• Hermit crab shell exchange algorithm: a new metaheuristic. Evolutionary Intelligence, 2022.
• Preparation of crab-shell-based N, O co-doped graded porous carbon for supercapacitors using the confined nanospace deposition method. Waste Disposal & Sustainable Energy, 2024.
• Same resource, different benefits: hermit crab shell structure advantages owners, but not intruders in agonistic interactions. Hydrobiologia, 2021.
• One-step molten salt-assisted preparation of crab shell-based hierarchical porous carbon for capacitive energy storage. Diamond and related materials, 2024.
• Shell-selection behavior of the hermit crab Pagurus granosimanus in relation to isolation, competition, and predation. Journal of Shellfish Research, 2007.
• Shell choice in Pagurus longicarpus hermit crabs: Does predation threat influence shell selection behavior?. Behavioral Ecology and Sociobiology, 2004.
• Less choosy or different preference? Impact of hypoxia on hermit crab shell assessment and selection. Animal Behaviour, 1998.
• The importance of various shell characteristics to the shell-selection behavior of hermit crabs. Journal of Experimental Marine Biology and Ecology, 1978.
• Impacts of toxic red tide algae Karenia brevis on shell selection behavior of the hermit crab Pagurus longicarpus. Journal of Experimental Marine Biology and Ecology, 2023.

This article is educational and is not a substitute for veterinary diagnosis or treatment. Contact a veterinarian for advice about an individual animal.