Hermit crabs are ectotherms. An ectotherm is an animal that needs to draw heat from external sources, not its own body. Ectothermic has replaced the previous, more colloquial term, cold-blooded.
Hermit crabs flourish at a temperature of 80 degrees Fahrenheit. Heat lamps or under tank heaters help maintain the optimal temperature. A humidifier is also worthwhile. If you have no power or prefer not to use electrical appliances to save money, offer more substrate for deeper burrowing and insulate the tank with towels.
Hermit crabs are not the most robust of pets. Owners need to be careful to match the living conditions of the wild in a hermit crab aquarium. A significant part of this is keeping your hermit crabs warm.
Are Hermit Crabs Ectotherms?
In the wild, hermit crabs can draw heat from the rays of the sun. Although hermit crabs are nocturnal, they tend to hail from tropical climes. This ensures that a little time spent in the sun goes a long way.
In captivity, this is not an option. You can consider taking your hermit crabs outside for exercise or play. This is not a sustainable, long-term solution, though. Hermit crabs cannot live outdoors indefinitely.
You will need to arrange sufficient heat for your hermit crabs in their habitat. Failure to do so could be fatal for your pets.
What Temperature Should Hermit Crabs be Kept At?
As explained by the Journal of Thermal Biology, ectothermic animals do not have one set, preferred temperature. A hermit crab may require a different temperature than a snake, for example.
Most hermit crab experts recommend following the 80/80 rule for these animals. This means a habitat of humidity of 80% and a temperature of 80 degrees Fahrenheit. This could be considered an oversimplification of the needs of hermit crabs, though.
80 degrees is an ideal temperature. However, wild hermit crabs are used to an array of different temperatures. Gusts of wind, for example, may create temperature variances.
If your hermit crabs are too hot, they will leave their shells. This suggests they are uncomfortably hot. Reduce the temperature by a degree or two.
The same applies to aquatic hermit crabs. A water temperature of 80 degrees is often fine for these creatures. Some hermit crabs prefer a water temperature closer to 72 degrees Fahrenheit. Again, watch your hermit crabs for signs of discomfort.
It is likelier that your hermit crabs will get too cold than too hot. If in doubt, keep hermit crabs warm.
Do Hermit Crabs Get Cold?
Hermit crabs feel the cold. These are warm-weather animals that live on the beach. You will never find a hermit crab in the Antarctic.
As discussed, hermit crabs in the wild know how to manage their body temperature. They have experience in understanding how to stay warm. In captivity, hermit crabs are reliant on owners to meet their needs.
If hermit crabs get cold, they become weak, listless, and sick. This makes particular times of the day and certain seasons more dangerous than others. Hermit crabs need additional heat sources during winter. Also, you must learn how to keep hermit crabs warm at night.
How to Tell if a Hermit Crab is Too Cold
The easiest method is to get a thermometer for your hermit crab enclosure. These will only cost around $15. Place this in the tank and keep an eye on the base temperature. If it drops below 80 degrees, watch for any reaction. Signs that hermit crabs are feeling the cold include:
- General lethargy
- Consistent burrowing under the substrate
- Hiding within the shell
- Color fading to a dull gray (also a sign of impending molt)
None of these behaviors should be ignored. If left cold for too long, hermit crabs will sicken and die. They will also become increasingly stressed by cold conditions. This will likely result in limb shedding.
Can Hermit Crabs Live in Cold Weather?
As discussed previously, hermit crabs dislike cold weather climates. This is why you cannot keep hermit crabs outside, and certainly not in a pond. The temperatures will eventually drop to a deadly level.
Marine Behavior and Physiology explains how wild hermit crabs adapt to drops in temperature. These animals will cluster and huddle up. This improves their chances of survival during adverse weather conditions.
To keep hermit crabs safe in cold weather conditions, you will need additional heat sources and peripherals. It is unfair and unrealistic to expect hermit crabs to keep themselves safe in cold conditions.
Keeping Hermit Crabs Warm
Land hermit crabs need particular attention. These animals are delicate when faced with suboptimal temperatures. Consider one of the following techniques to keep your hermit crabs comfortable.
Heat lamps are a common accessory for ectothermic pets. You’ll find these items online or in any pet store. They will offer a direct heat source to an aquarium, in addition to acting as a light during daylight hours.
Wherever possible, install an incandescent white lightbulb in your heating lamp. This is preferable to a reptile heating bulb, which could run too hot. A wattage of 25w is usually enough, but this may be a vase of trial and error. Install a bulb and check your thermometer. Do not pick up anything so bright it will hurt the eyes of your hermit crabs.
If there is a flaw with heating lamps, it is their comparative inflexibility. If you have a large tank, this lamp will only heat certain parts of it. This will essentially create basking spots, but not warm the habitat as a whole. If this is a concern, consider under tank heaters instead.
Under Tank Heaters
Undertank heaters are commonly used in fish aquariums. These appliances can be secured to the bottom of the habitat or the side. They look like conventional hermit crab heat pads but are fastened to a tank.
If you place a heater under a tank, it will create a constant source of warmth below the substrate. It may be too hot for some hermit crabs, though. With this in mind, consider placing the heater on the side of the tank.
These heaters can run warm, sometimes generating temperatures of 85 degrees or above. By locating it on the side of a tank, though, your hermit crabs have a choice. They can station themselves wherever they are most comfortable.
As discussed, the tank of hermit crabs must run humid. If a hermit crab enclosure regularly drops below 80% humidity, your pets are at risk of suffocation. Always keep an eye on a hygrometer to ensure your hermit crabs are safe.
Some owners increase humidity with a misting spray. An alternative could be to get a micro-humidifier to place inside the tank. This can be expensive, but it solves two problems at once. It increases humidity and temperature by releasing warm air.
A humidifier will need to be refilled regularly, and you’ll need to play with the settings to get levels just right. This is less work than constantly misting a tank, though. If you live in an arid climate, a humidifier is a great addition to your aquarium.
External Heat Sources
If you are not keen on applying a heat source directly to an aquarium, consider adding one just outside. A portable heater, for example, could be wheeled and plugged in beside a tank.
Be careful with these. They can run hot, so you do not want to damage the aquarium walls with heat. Most portable heaters can be attached to a timer, though. This makes them ideal for warming hermit crabs at night.
Set the heater to come on when the temperature is scheduled to be coolest and to switch off when the sun rises. Checking the thermometer during the first night to ensure the heat is reaching the interior of the enclosure.
Heating Sources to Avoid
Not all electrical heating sources for ectotherms are safe for hermit crabs. Some are outright dangerous. As we mentioned previously, allowing hermit crabs to get too hot is just as dangerous as leaving them to freeze.
If looking to provide heat for your hermit crabs, these devices and methods must be avoided. If you already have them in a hermit crab habitat, remove them post-haste.
Heating pads are the materials used in the under tank heaters that we discussed earlier. Some owners erroneously think these hermit crab heating pads can be left in a habitat.
As explained, these heating pads run hot. If they bring the enclosure temperature up to 85 degrees when placed outside, imagine how scorching they will be to touch directly?
If your hermit crabs are still cold with a heating pad attached to the bottom or side of the habitat, attach a second one outside. Never leave the heating pads in the aquarium for hermit crabs to step on. This will not end well.
Hot rocks are a popular addition to lizard enclosures. They are unsuitable for hermit crabs, though. Your hermit crabs can easily burn themselves.
Hot rocks concentrate all heat in one small place. This means that they can create an intense level of heat. This means just brushing past a hot rock can cause serious burns.
Also, hermit crabs love to climb on rocks. Sometimes, they may even fall asleep in such a location. If the hot rock switches on, the hermit crab will be fried before it knows what is happening.
How to Keep Hermit Crabs Warm without a Heater
You need to understand how to keep hermit crabs warm in winter without external appliances. There are many reasons why this is important.
- Electrical heat appliances will increase your energy bills
- Electrical appliances can run noisily
- Adverse weather, such as storms, can lead to power blackouts
- Direct sources can cause excess heat if left running too long
- Electrical appliances can break down without warning and take time to repair
Relocate the Aquarium
Sometimes, the simplest solution is also the most effective. Certain rooms in a house are invariably colder than others. Consider moving your aquarium to another part of the home that runs a higher room temperature.
This could be challenging with cabinet aquariums or anything affixed to a wall. In this instance, consider using a second habitat. You should always have two aquariums anyway. Your hermit crabs need somewhere to be rehomed during deep cleans and molting.
The only problem with this plan is that a second tank is likely small. It may cause the hermit crabs some distress to be cramped. They’ll huddle for warmth initially but soon grow distressed. Factor this into your decision.
Apply Additional Substrate
Another quick and easy win to warm up hermit crabs is applying more substate to a habitat. As per Ecology, wild hermit crabs bury themselves increasingly deep in the substrate during cold seasons. Your hermit crabs will imitate this action.
The deeper under the substrate hermit crabs go, the more protection they’ll have from the cool air. This is not necessarily a sustainable solution, though. Consider why your hermit crabs are so cold. More substrate cures an ill but does not diagnose a symptom.
If you are adding more substrate, consider using soil. This can either complement or replace sand. Creature soil is particularly effective, as this contains moss. This will slightly increase the humidity in the tank, which leads to higher temperatures.
Take a look in any novelty or gift store in winter and you’ll find hand warmers. These are small pieces of plastic that are worn with gloves. Activate the hand warmers and they release a small, welcome amount of warmth.
This can be a fast way to take the edge off a cold night for hermit crabs. Enable hand warmers and leave them in the aquarium. This will offer some brief respite from the cold without putting hermit crabs in danger.
Hand warmers are cheap, so this is a cost-effective solution for short-term heat. Hand warmers are stone-cold within a couple of hours. They should be removed as soon as the heat subsides. This will prevent curious hermit crabs from attempting to eat them.
Spray Warm Water
We mentioned previously that misting spray would increase humidity in a habitat. Using warm water will be even more impactful. Boil up some water (filtered to remove any chlorine), let it cool, then spray.
Do not spray the water straight on your hermit crabs. Equally, resist the urge to create a warm bath. Prolonged exposure to warm water can harm your hermit crabs. As a quick fix for a low temperature, use warm water in a spray bottle.
Insulate the Tank with Towels or Blankets
You could consider applying insulation to your hermit crab tank. This is easily achieved by wrapping towels or blankets around it.
Ensure that your hermit crabs have already enjoyed 12 hours of light before attempting this. Equally, do not cover every square inch of the enclosure. You’ll need to leave enough space for hermit crabs to breathe.
All the same, towels and blankets will keep heat within the aquarium. This is a fast way to keep hermit crabs warm using everyday items.
Keeping hermit crabs warm, especially during winter and at night, is critical. The most effective way to create a warm environment for hermit crabs is through direct heat sources. These are invariably electrical.