Last Updated on September 2, 2023 by Joanne Harper
Hermit crabs are nocturnal animals, allowing them to avoid sun exposure. Overheating is an ever-present risk for hermit crabs, so the tank’s temperature must always be monitored.
A temperature above 80 degrees Fahrenheit is too hot for hermit crabs. Warning signs of overheating include diurnal activity, leaving the shell, a musty smell, and brown liquid discharge.
Left ignored, these symptoms can be life-ending, so you must cool down the tank.
Preventing hermit crabs from getting too hot is preferable to dealing with the consequences of overheating. Add a thermometer for the tank to monitor the temperature at all times.
Are Hermit Crabs Warm or Cold-Blooded?
Hermit crabs are ectothermic (cold-blooded) creatures, which means they depend on the temperature around them to generate warmth.
As per Estuarine, Coastal, and Shelf Science, wild hermit crabs hide when the sun is at its highest, as befits nocturnal creatures. This illustrates that hermit crabs avoid excess heat.
Similarly, if the temperature gets too cold, hermit crabs will adjust how they live.
Do Hermit Crabs Like Hot or Cold?
The ideal temperature for hermit crabs is 72-80 degrees Fahrenheit.
Marine hermit crabs thrive in water in the low 70s but no colder. If hermit crabs live with fish, the water may need to be slightly warmer.
Land hermit crabs thrive at 80 degrees. However, you may need to cool them off occasionally.
Can Hermit Crabs Get Too Hot?
Hermit crabs can overheat due to:
- Excessive humidity.
- Too much substrate.
- Prolonged use of artificial heat sources.
- High room temperature.
- Too many hermit crabs in a small space.
Monitor the behavior of hermit crabs during the hottest times of the year. If anything looks amiss, you should adjust the temperature of the tank.
How Hot is Too Hot for Hermit Crabs?
Most owners abide by the 80/80 rule – 80% humidity and a temperature of 80 degrees Fahrenheit.
Set the temperature in the enclosure to 80 degrees and check how the hermit crabs react. You may need to reduce this temperature, especially for marine hermit crabs.
Signs of Hermit Crabs Overheating
You must learn the symptoms of hermit crabs overheating. Any time the temperature in a tank exceeds 80 degrees Fahrenheit, check for any signs of discomfort.
Active During the Day
If the tank is too hot, hermit crabs will become active during the day.
Ordinarily, hermit crabs burrow under the substrate and sleep during daylight hours. Then, they emerge at night, feeling refreshed, comfortable, and well-rested.
Excessive heat prevents hermit crabs from sleeping; they’ll start to feel uncomfortable burrowed under the substrate. This reversal of the day-night cycles will cause stress to hermit crabs.
You may see hermit crabs for 1-2 hours in the morning, which is normal. If they’re active all day, check the temperature of the tank in case the hermit crabs require a slightly cooler climate.
Leaving the Shell
The most common sign that hermit crabs are too hot is leaving the shell, as they’ll never leave their home without good reason. This leaves them vulnerable to attack and the elements.
According to the Journal of Experimental Marine Biology and Ecology, the shells of hermit crabs are heat conductors. By leaving the shell, the hermit crab is attempting to cool off.
Shells protect hermit crabs from the rays of the sun. If hermit crabs are without a shell, they’re exposed to heat sources, drying them out and leading to suffocation.
Discharge of Brown Liquid
Brown liquid, especially discharged from a hermit crab’s mouth, means that hermit crabs detach from their exoskeleton.
A foul, musty stench often accompanies this symptom. The tank should smell comparatively neutral, so any smell that captures your attention is rarely a good sign.
If you observe brown liquid around your hermit crabs, and they’re not scheduled to molt, take action.
How To Cool Off Overheated Hermit Crabs
Avoid removing the hermit crabs from their enclosure. They’ll already be stressed, and handling will magnify the problem. Instead, it would help if you cooled them off inside the tank.
Reduce Room Temperature
Start by reducing the ambient temperature in the room that houses the tank. Open some doors and windows., turn on the air conditioning, and switch on any freestanding fans in the room.
This won’t always be effective in the summer months. If the ambient temperature remains high, you’ll need to focus on cooling the enclosure by doing the following:
You shouldn’t let the humidity drop below 80% for too long. However, a brief drop in humidity is better than overheating. Lift the lid to release some humidity.
If you have a humidifier in the tank, switch it off. If you’re using Saran wrap to retain humidity, remove this temporarily. As humidity increases temperature, this will cool the tank down.
Place something over the tank to prevent the hermit crabs from escaping, but leave it open for at least an hour because this allows some humidity to dissipate.
Once your hermit crabs have recovered from their overheating ordeal, restore the humidity to 80%.
Fans and Breezes
Micro-fans are widely available. These are primarily used for cooling off electrical appliances but can provide a short burst of cool air when hermit crabs are overheating.
An alternative is to fan your hermit crabs manually. Open the tank’s roof and create a breeze with a paper fan or magazine.
Cool Bathing Water
When hermit crabs are overheating, they’ll likely head to their water bowl.
This way, they can submerge and dampen their gills and skin. Encourage this activity by placing a small piece of an ice cube in the water.
Use a bowl of salt water because marine salt will make the ice melt faster and the water colder. As discussed, hermit crabs can get too cold.
Frozen Water Bottles
Water bottles make good toys for hermit crab enclosures.
Hermit crabs will enjoy climbing over them and attempting to roll them over. Leaving a water bottle in the freezer beforehand will also aid with overheating.
Don’t fill a bottle with tap water because this is toxic to hermit crabs and even more dangerous when hermit crabs are overheating. Put the water through a purifier to reduce the risk.
How To Prevent Overheating in Hermit Crabs
You can cool off overheating hermit crabs by doing the following:
Hermit crabs appreciate space. If you have more than two hermit crabs, select a tank no smaller than 10 gallons. The more space they have, the less likely hermit crabs will overheat.
Think about where the tank faces. Don’t position a tank in front of a window where hermit crabs risk baking in the sun. Find a room that has a suitable ambient temperature.
Shaded Hiding Places
Hiding is an everyday activity for hermit crabs; it’s a way to stay safe, cool, and occupied. The more shaded space your tank offers, the more comfortable it’ll feel.
As per Crustacean Research, many hermit crabs seek shade by burrowing under the substrate. This can be dangerous, magnifying the risks of overheating. Instead, provide shaded spots for hermit crabs.
Rocks are ideal, but cardboard, halved coconuts, and freestanding cuttlebone are beneficial.
Airing The Tank
Occasionally, air out the tank by lifting the lid for a few minutes. Add a cold water spray or use a fan while you do so.
Even if this is for 10 minutes, it’ll prevent heat from becoming trapped in the tank. You can do this while spot cleaning, and while doing so, trim any moss growth to keep humidity levels manageable.