Hermit crabs are nocturnal creatures because it allows them to avoid exposure to the sun. Overheating is an ever-present risk for hermit crabs, so the aquarium’s temperature must be monitored at all times.
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 lethal, so you must cool down the aquarium.
Preventing hermit crabs from getting too hot is preferable to dealing with overheating once it’s become a problem. Get a thermometer for the aquarium so that you can monitor the temperature.
Are Hermit Crabs Warm or Cold-Blooded?
Hermit crabs are ectothermic (cold-blooded). This means that hermit crabs are dependent on the temperature around them as they cannot generate warmth by themselves in the way that humans do.
It’s easy for hermit crabs to get too cold, especially during winter. Of equal danger is hermit crabs getting too hot, though. It’s just a balancing act.
As per Estuarine, Coastal, and Shelf Science, wild hermit crabs are occasionally spotted during the day. They usually hide when the sun is at its highest, as befits nocturnal creatures. This suggests that hermit crabs avoid excess heat as much as cold.
Do Hermit Crabs Like Hot or Cold?
Hermit crabs need optimal temperatures. There is little room for maneuver as hermit crabs are delicate creatures. The temperature sweet spot for hermit crabs is between 72 and 80 degrees Fahrenheit.
Marine crabs thrive in water at the lower end of this scale, but will be fine at 80 degrees. If your hermit crabs live with fish, the water may need to be warmer. If they live alone, stick with the low 70s, but no colder.
Terrestrial hermit crabs do better at the upper end of this scale. As we’ll discuss shortly, 80 degrees should be the target temperature. You may need to offer occasional cooling techniques, though.
Can Hermit Crabs Get Too Hot?
Hermit crabs can overheat. Causes of this could include:
- 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. 80 degrees is the upper limit of hermit crab comfort, though. 81 degrees or above is too hot.
Set the temperature in a hermit crab enclosure to 80 degrees, to begin with. This should always be your base target for the aquarium climate. Watch how the hermit crabs react. If they appear happy, leave it be.
You may need to reduce this temperature, especially for marine hermit crabs. If they show any signs of distress, reduce the temperature at once. Your hermit crabs are at risk of overheating.
Signs of Hermit Crabs Overheating
You must learn the symptoms of hermit crabs overheating. Any time the temperature in an enclosure exceeds 80 degrees Fahrenheit, watch for signs of discomfort.
Active During the Day
If the enclosure of your hermit crabs is too hot, they will become active by day. Ordinarily, hermit crabs burrow under the substrate and sleep during daylight hours. They emerge at night, feeling refreshed and comfortable.
Excessive heat will prevent hermit crabs from sleeping. They will start to feel uncomfortable burrowed under the substate. This reversal of the day-night cycles will cause stress to hermit crabs.
You may see your hermit crabs for an hour or two in the morning. That is perfectly normal. If they are active all day, check the temperature of your aquarium. Your hermit crabs may welcome a slightly cooler climate.
Leaving the Shell
Arguably the most common sign that hermit crabs are too hot is leaving the shell. Hermit crabs will never leave their protective shell without good reason. This leaves them vulnerable to attack from other hermit crabs, as well as the elements.
As per the Journal of Experimental Marine Biology and Ecology, the shells of hermit crabs are heat conductors. By leaving the shell, the crab is attempting to cool off. As well as the stress that accompanies not having a shell, there are other issues.
Shells protect hermit crabs from the rays of the sun. If your hermit crabs are without a shell, they are exposed to heat sources. This could lead to the hermit crabs drying out and suffocating before long.
Discharge of Brown Liquid
Brown liquid, especially discharged from a hermit crab’s mouth, is an emergency. This means that hermit crabs are detaching from their exoskeleton. It is too hot for the crabs to survive.
A foul, musty stench often accompanies this symptom. The habitat of your hermit crabs should smell comparatively neutral. Any smell that captures your attention is rarely a good sign.
If you spot any brown liquid around your hermit crabs, and they are not scheduled to molt, take action straight away.
How To Cool Off Overheated Hermit Crabs
Avoid removing the hermit crabs from their enclosure. They will 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 your aquarium. Open as many doors and windows as you can. Turn on air conditioning and switch on any freestanding fans in the room.
This will not necessarily be effective in the summer months. If the ambient temperature remains high, you’ll need to focus on cooling the enclosure.
Humidity is important in a hermit crab enclosure. You can never let it drop below 80% for a prolonged period. A brief drop in humidity is the lesser of two evils compared to overheating, though.
Lift the lid of your hermit crab tank to release some humidity. If you have a small humidifier in the tank, switch it off. If you are using Saran wrap to retain humidity, remove this. As humidity increases temperature, this will cool the tank down a little.
Place something over the tank to prevent your hermit crabs from escaping, but leave it open for at least an hour. This allows some of the humidity to dissipate. Once your hermit crabs are safe and have recovered from their overheating ordeal, return humidity levels to 80%.
Fans and Breezes
Micro-fans are widely available. These are primarily used for cooling off electrical appliances, but they can help a short burst of cool air when hermit crabs are overheating is needed.
An alternative is to fan your hermit crabs manually. Open the tank’s roof and create this breeze with a paper fan, or even a magazine. This will create a welcome breeze.
Do not assume that hermit crabs want or need this at all times. Under ordinary circumstances, hermit crabs loathe draughts. Overheating is the only time this practice will inspire relief over distress.
Cool Bathing Water
When hermit crabs are overheating, they are likely to head straight to their bathing water. This way, they can submerge and dampen their gills and skin. Encourage this activity by dropping an ice cube or two in the water.
Use your saltwater bath for this technique. The presence of 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 great toys for hermit crab enclosures. Your 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.
Do not fill a bottle with tap water as this is toxic to hermit crabs, and even more dangerous when they are overheating. Put the water through a purifier to reduce the risk if water starts to leak.
How To Prevent Overheating in Hermit Crabs
You can aid hermit crabs that are overheating by reducing their body temperature. Here’s how:
Ensure that you are housing your hermit crabs properly. This involves getting an aquarium that’s the correct size and placing it in the right location.
Hermit crabs appreciate space. If you have more than two hermit crabs, pick up a tank no smaller than 20 gallons. The more space they have, the less likely they are to overheat.
Think about where the aquarium faces, too. Do not place in front of a window, where your hermit crabs are at risk of baking in the sun. Find a room that offers a suitable ambient temperature.
Shaded Hiding Places
Hiding is an everyday activity for hermit crabs. It’s a way to stay safe, cool, and simply for recreation. The more shaded spaces your aquarium offers, the more comfortable your hermit crabs will be.
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 your hermit crabs.
Rocks are ideal for this, but you can get creative. Cardboard, halved coconuts, and even freestanding cuttlebone could all be applied. Anywhere your hermit crab can shield from heat will be embraced.
Airing The Tank
Every once in a while, air out your hermit crab tank. Just lift the lid for a few minutes. Add a cold water spray, or use a fan while you do so.
Even if this just for 10 minutes a day, it will start to have a positive impact. It prevents heat from becoming trapped in the habitat. You can tie this in with spot cleaning. While you’re doing so, trim any moss growth to keep the humidity levels manageable.
Most habitats will require a heating source to keep hermit crabs warm during winter. Only use these appliances only when necessary. In the height of summer, you are unlikely to need to add additional heat.