How to Care for Hermit Crabs

Hermit crabs (also known as shell-dwelling crabs) make fantastic pets. While they may not be as affectionate as puppies, entering the captivating world of hermit crabs allows children to learn the importance of caring for a living creature. This article will provide insights into the habitat and care needed for these fascinating crustaceans.

Select an appropriately sized glass tank to create the 'crabitat'. 'Crabitat' refers to the artificial habitat for hermit crabs. A tank with a capacity of 40 to 80 liters is ideal for housing two to four small crabs. Hermit crabs are social creatures, so at least one other crab should be present for interaction. A suitable enclosure should maintain humidity while allowing airflow. Options include fish tanks, reptile enclosures, or even repurposed old water containers from your rooftop. Acrylic tanks or clear plastic bins are also good choices as they retain moisture and heat effectively.

Ensure proper humidity levels for the tank. It's recommended to equip the tank with a hygrometer and thermometer. These will help you monitor and maintain optimal temperature (24-28°C) and humidity (75-85%). Hermit crabs breathe through their gills, which need to remain moist. If their gills dry out, they will suffocate. Therefore, the environment must maintain at least 75% humidity. If humidity drops below 70%, the crabs may struggle to breathe and eventually die over time.

• Adding moss to the tank is a natural way to increase humidity. Moss retains moisture and serves as food for the crabs. You can also use sponge material, which holds moisture well. However, sponges get dirty quickly, so they should be replaced every two or three weeks.

Maintain the appropriate temperature for the tank. Hermit crabs are tropical creatures and thrive in warm environments. Their ideal temperature range is between 24-29°C. Excessive heat damage is irreversible, and temperatures that are too low can slow down their metabolism. It's a good idea to install a heater behind the tank to maintain temperature and humidity. If the tank is not properly set up, the crabs may become lethargic, lose limbs, or even die.

Prepare the substrate. The substrate is the material you spread on the bottom of the tank. It is best to use sand that is the size of sugar grains, as finer sand can enter the shells of the crabs while they move, causing serious issues. You can moisten the substrate with dechlorinated saltwater to create a consistent "sandcastle" structure. You can also use compressed coconut fiber (available at aquarium shops). After loosening the coconut fiber, sprinkle it with saltwater to provide humidity and prevent mold growth. Avoid using aquarium decorative gravel (as crabs cannot burrow in it) or calcium sand (which can harden and cause odor). The substrate should be at least 3-5 times the height of the hermit crab and should allow them to dig burrows, hide, and molt.

• Some hermit crabs love to crawl into damp moss for molting. (Note: not Spanish moss or synthetic moss used for decoration!)

Keep the substrate clean. Dirty substrate can foster harmful mold growth. It's recommended to replace the substrate every 6 months. However, check monthly for any mold, ants, or pests damaging the substrate. If you notice any problems, change the substrate immediately. You can also "spot clean" by removing droppings or leftover food the crabs scatter on the substrate. Do not clean the tank when the hermit crabs are in the process of molting (they will bury themselves in the sand and emerge after they’ve changed shells). Crabs are very weak during this time, so avoid moving them.

• If you want to take extra precautions, you can sterilize the sand substrate by baking it. Place the sand in a large pan (use a separate pan to ensure hygiene) and bake it in the oven at 120°C for about 2 hours.
• Once every two or three weeks, boil all the shells in the tank with dechlorinated saltwater to ensure no bacteria or mold will harm the crabs. Let them cool before returning them to the tank.

Buy toys for your hermit crabs. Hermit crabs are like professional climbers. In the wild, they often climb large rocks at low tide to search for food. Sometimes, hermit crabs are called "tree crabs" because they can climb trees to feed on insects and plants. Avoid purchasing painted toys to prevent the risk of paint chipping off and being ingested by the crabs, which could harm their digestive system. Some toys you can buy include:

• Climbing toys are essential. Natural materials like almond wood or tree roots are very popular, as they are non-toxic and provide plenty of holes for the crabs to cling to. You can place it in a corner of the tank, making sure the crabs cannot climb out through this way. Besides almond wood, Lego blocks and hemp fiber nets are also great options, available at pet stores.
• Natural toys: Stones and shells. Scattering beach-found items around the tank can help make your crabitat lively. Hermit crabs may even eat the shells. Be sure to boil everything to sterilize before placing them in the tank.
• Plastic toys: Plastic reptile plants also work well for crabs to climb or hide in, but make sure to close the lid of the tank tightly to prevent the crabs from escaping and dying. Ensure that the crabs do not consume the plastic; if they do, remove it immediately.
• Never use "split pine wood" for reptiles, as it contains stimulating chemicals that could poison your crabs.

Prepare a hiding place for your hermit crabs. Like many other animals, hermit crabs seek shelter when they feel threatened. You can use coconut shells, old flower pots, large seashells, or other similar items. Just make sure the crabs can easily crawl in and out without getting stuck or have enough space to dig around.

Introduce some live plants into your tank. Plants are an essential addition. Specifically, bamboo (except for the lucky bamboo), carnivorous plants (air plants), and spider plants are safe options. However, keep in mind that the crabs may eat them at any time, so it's better to wait until the plants are well-established before adding them to the tank.

Provide water for your hermit crabs. All hermit crabs need access to both fresh and saltwater. Prepare two dishes with these types of water, as the crabs need to balance the salinity inside their shells. The water dishes should be deep enough for the crabs to soak their shells (C. Perlatus crabs love to immerse themselves in water). Create a sloped water area, from shallow to deep, surrounded by stones or something to help the crabs climb. Avoid using plastic as it's slippery, making it harder for the crabs to climb.

• If you have a large hermit crab and a smaller one, you can add small rocks or a piece of natural sponge to the water dish to ensure the larger crab can soak properly without the smaller one getting stuck or drowning.
• You can buy marine aquarium saltwater (not freshwater) for the tank. Avoid using table salt, as the anti-caking agents in it can harm the crabs. Some hermit crab salt brands are actually table salt, so be careful when mixing saltwater to ensure proper salinity. Use trusted brands like Instant Ocean or Oceanic.

Ensure the water is dechlorinated. Tap water contains chemicals like chlorine, chloramine, and heavy metals that can cause the hermit crabs' bodies to swell, potentially leading to sudden death from suffocation. Distilled water removes chlorine, but chloramine will remain, so if you use tap water, you should use a water treatment system to remove these harmful substances.

• If you don't have a water treatment system, you can use spring water as a substitute for tap water. However, make sure it's pure spring water without any additives. For example, Dasani water contains magnesium sulfate (Epsom salt) to "enhance the flavor", which is not safe for crabs.

There are many types of hermit crabs you can purchase. In the United States, there are six species of hermit crabs available. Most of them belong to the Coenobita genus. The Purple Pincher is the easiest for beginners, as it doesn't require too many details or meticulous care.

• The most common one is the Caribbean hermit crab (Coenobita clypeatus), often referred to as "PP" for "purple pincher." They got this name due to their purple patches and were first discovered in the Caribbean Islands. If you visit a pet store, you're likely to find one of these as your first hermit crab. There are also other types, such as Rugosus, often called "Rug" or "Ruggy" (rugosus), Strawberry (perlatus), Ecuadorian or "E" (compressus), Cavipe or "Cav" (cavipes), Komurasaki "Viola" (violascens), and Indonesian or "Indo" (brevimanus).

Handle them carefully. When you first bring home your hermit crab, be patient as it takes some time for it to adjust to its new home. Leave it alone for a few days in its tank. When you notice the crab no longer hides in its shell, it's a good time to gently interact with it. Let the crab explore your hand and get comfortable with it.

• Once you bring the hermit crab home, it will go through a "stress" period that can last anywhere from a few days to several months. During this time, you must provide fresh food and water frequently and avoid disturbing it. Even experienced hermit crab owners may find it difficult to help the crab overcome this period, watching them struggle with Post Purchase Stress Syndrome (the stress of an unfamiliar environment), potentially leading to death.

Hermit crabs must undergo molting and shell replacement. If your crab buries itself for a few weeks, don't panic. As long as there’s no foul, fishy smell, everything is fine. During this time, avoid disturbing them, as they need solitude to molt and will die from stress if interrupted. When a hermit crab’s body grows too large, its exoskeleton becomes too tight, necessitating molting, similar to how snakes shed their skin. However, don't throw away the old exoskeleton! Crabs need to consume it to strengthen their new exoskeleton.

• If one of your hermit crabs appears unwell, don’t worry. Keep it in a separate tank with the appropriate substrate, water, and food. If it acts sick, it may be preparing to molt. The isolation tank should be set up with the correct temperature and humidity, as mentioned earlier.

Prepare new shells for your crab. As your hermit crabs grow, they will need larger shells. Always have multiple shells of various sizes scattered around the tank. This is essential. Occasionally, replace them with shells of different styles and colors.

• Purple Pincher crabs prefer shells with round holes rather than oval ones. Ecuadorian hermit crabs, on the other hand, favor oval holes because they have somewhat flat bellies.
• Never buy painted shells! Even if the manufacturer claims they are safe, the paint can chip off, and the crabs could ingest it and get poisoned. Many crabs prefer "natural" shells over artificial ones, even if they don’t fit perfectly. See the 'Warnings' section for more information on which shells to avoid.

Provide a regular and varied diet. Hermit crabs are known as the “laborers of nature” because they will eat almost anything. Be cautious, as some foods contain preservatives and copper sulfate, which can harm your crabs. Avoid giving them anything spicy, hot, or containing preservatives.

• Hermit crabs enjoy fish fillets, fresh shrimp, dried shrimp, bloodworms, seafood, and more. You can purchase these from local grocery stores or bait shops.
• If you cook at home, you can give them a piece of beef or chicken, unseasoned and just lightly grilled. Alternatively, hermit crabs can also eat raw meat.
• If you have more than twenty hermit crabs, consider feeding them fish heads. Fishmongers are often willing to give you fish heads that would otherwise be discarded (except for large fish heads like salmon). Place the crabs in a large tank or a clean plastic container (without a lid or with large holes), add the fish heads, pour in a bowl of water, and leave them to enjoy for a few hours. You probably won't want to do this too often due to the strong fishy smell, but your crabs will love you for it.

Know which fruits and vegetables hermit crabs like. In addition to meat, hermit crabs love eating fruits, vegetables, and other organic waste (since they are nature's cleanup crew). Be sure to change their food daily or at the end of the day, as the crabs enjoy burying their leftover food, which can lead to mess and mold growth.

• Hermit crabs enjoy fresh fruits such as pineapple, apples, pears, grapes, watermelon, mango, papaya, strawberries, bananas, etc. Be sure to wash the fruits before cutting them to avoid pesticides.
• Hermit crabs go wild for shredded coconut.
• They also enjoy natural peanut butter on toast, boiled eggs, eggshells (boiled), and plain popcorn (no salt, no butter).
• Avoid any plants from the onion family (onions, garlic, etc.).

Play with them. Most hermit crabs love attention. When they wake up, gently take them out of the tank. How should you play? Climbing! Let them crawl on your shirt while you watch TV or across both of your hands (like a treadmill for crabs). The key is to be careful not to let them fall, and don't let them out of the tank for too long as they need the proper humidity. Falling from a height of one meter can be fatal, and they might reflexively pinch you out of fear of falling. Keep the hermit crab safe, and you won’t get pinched.

• Remember, hermit crabs need humidity. The typical indoor humidity is around 40%, and it can be even lower with air conditioning. When a hermit crab is kept in low humidity, it feels like it's holding its breath for too long.

Be cautious because hermit crabs can pinch. Apart from self-defense, they may pinch for no reason, so be prepared. If they pinch you, don’t try to make them release by spraying water or putting them under a running faucet, as this can make them pinch harder. Always be careful when handling a hermit crab. You can reduce the chances of being pinched by keeping your hand straight and tense so the crab doesn't have much skin to grab onto.

• Don't make loud noises or cause sudden movements when handling the crab, as this can stress it out.
• Choose a crab that looks lively, not sluggish. While sluggishness may indicate illness, sometimes a crab might just be stressed or shy at first.
• If you smell something unusual, like the odor of dead fish, it could be a sign of a dead crab. But before searching for the cause, consider the food you've provided. Did you recently feed them raw seafood? It could take a month before any leftover food is discovered in the tank. Hermit crabs love burying their food. That's why you should change the substrate every month or longer (unless it's molting time).
• If a hermit crab pinches you, it doesn’t mean it hates you; it’s simply scared or hungry. Put it back and wait a moment before picking it up again, and remember not to shake your hand, as this will make the crab more scared and pinch harder. Ensure that there’s enough food in the tank. Don't punish your tiny friends if they pinch—they're just acting on instinct and don't understand what they’re doing.
• Hermit crabs cannot breed in captivity. They need a tropical and oceanic climate to reproduce. Unless you have an enormous tank designed specifically for this purpose, don’t expect to see a baby hermit crab.
• Do not feed hermit crabs anything before a long car trip, as motion sickness can be fatal for them.
• If your child has a hermit crab, advise them to wear gloves if they’re worried about being pinched.
• When handling the crab, place your hand on a surface like a table. This will help the crab feel less anxious and reduce the chances of getting pinched.
• Dip the crab in water for about one minute, then let it dry for five minutes if you want to clean it.
• If you notice the crab becoming less active and its eyes turning white, it might be preparing to molt. Place it in a separate tank in a suitable spot, and spray it with distilled water. Wait one to two days, and your pet should be fine... but remember, don't blow on it or touch it. The new skin is very sensitive, so don’t disturb it until its color returns to normal. This process takes about a month.

• If you're considering decorating the tank with driftwood, furniture, or wooden objects, think carefully. Many types of wood and plants are toxic to hermit crabs, like Lucky Bamboo and evergreen plants.
• Hermit crabs. Being crabs, they can deliver a painful pinch. Always keep an eye on children when they handle a hermit crab!
• Never drop the crab, as it could get injured or even die.
• If a local pest control team comes to spray your house regularly, make sure the hermit crabs aren't exposed to the spray. Move them to a different room for a few days and block the gap under the door with a towel to keep out the smell. While not insects, hermit crabs are close enough in relation to be affected by the chemicals, so be cautious.
• Do not use soap to clean the tank and toys! After removing all crabs and sand, you can use white vinegar to spray and scrub. Boil the toys, empty shells, and apricot wood in saltwater (to prevent mold) and place them on a towel to dry.

• A glass or plastic tank.
• A tank cover (glass or plastic).
• Two water dishes.
• Spring water and saltwater (do not "mix" saltwater with regular salt and tap water, as chlorine may harm the hermit crabs. If possible, add a few drops of water conditioner to neutralize it.)
• A shallow water dish big enough for the crab to soak in, but not too deep, as small crabs could drown (you can use a seashell to hold water for small crabs).
• A hiding space where the crab can have some privacy (you can cut a door into a coconut shell and flip it over, or bury half a flowerpot in the sand and make a ramp for the crab to climb into).
• At least 3 spare shells (one smaller, one about the same size, and one larger than the crab’s current shell). Do not use painted shells, as mentioned before, as the paint could harm the crabs if ingested.
• Substrate (at least 5 cm thick).
• White vinegar (for cleaning the tank) (optional).
• Fresh food (canned food can weaken the crab’s immune system).
• Something for climbing (like apricot wood or small bridges).
• A scooper (you can use a plastic spoon).
• Toys (available from pet stores or animal care shops).
• Gloves (just in case they pinch! Be careful with their claws).
• A thermometer and hygrometer (to measure temperature and humidity).
• A heater for the tank (if the indoor temperature is lower than 23°C).