Setting up the correct tank enclosure is vital for the survival of your pet hermit crabs. There are also significant differences between the breathing abilities of marine and land hermit crabs.
Land hermit crabs can drown in water. They can’t be underwater for too long because of their small gills. Most marine scientists believe they can only survive for 20-30 minutes. Terrestrial hermit crabs need small amounts of water to store water and keep their gills wet, and this is what enables them to breathe.
Owners must provide the right conditions for their hermit crabs to prevent them from drowning. This includes ramps, small pools of water, and accessories that enable them to escape the water if they get stuck.
Can My Hermit Crab Drown?
Even though hermit crabs are known as aquatic pets, marine and land hermit crabs have completely different requirements. Land hermit crabs are more commonly kept as pets and are most at risk of drowning.
Marine Hermit Crabs
Marine hermit crabs can’t drown. That being said, they need the right temperature and salinity to survive. Without it, they struggle to thrive and, in the worst cases, die almost immediately after their owners get them.
Aquatic hermit crabs have large, prominent gills that are located near their front walking legs. They breathe by absorbing oxygen from saltwater and transferring it to their gills. Oxygen then reacts with a hermit crab’s blood, where they release carbon dioxide through the mouth in the form of tiny bubbles.
Aquatic hermit crabs spend most of their time in the water. The wetter their gills, the more oxygen they breathe. As the Journal of Experimental Marine Biology and Ecology describes, exposure to saltwater changes a hermit crab’s breathing rate because the oxygen reacts to the water present in the gills.
Land Hermit Crabs
Land hermit crabs can’t breathe underwater and can drown. Their gills aren’t developed for prolonged exposure to water. While they need to dampen their gills to breathe, they can’t be submerged for too long. That’s why they also need various escape routes to get out of the water when they need to.
According to Comparative Biochemistry and Physiology, hermit crabs experience breathing difficulties when they’re exposed to the wrong environments. Land hermit crabs need to remain predominantly dry. However, owners must be careful with this, as they can suffocate if their gills are left to dry out.
Do Land Hermit Crabs Have Gills?
All hermit crabs have gills, but they need water to breathe. According to Smithsonian’s National Zoo & Conservation Biology Institute, land hermit crabs have much smaller gills than their marine cousins. This is predominantly why they can’t spend much time underwater.
A land marine hermit crab’s gills are located in the brachial chamber. Their moist gill chambers have several blood vessels that enable gas exchange. The chamber and gills act like lungs, allowing hermit crabs to breathe through the air instead of water. But, to breathe, they must obtain oxygen from humid air.
Hermit crabs also have a unique physiology, enabling them to store and retain water, which they obtain from the ground or in shallow pools.
As described, terrestrial hermit crabs can’t breathe underwater. They spend approximately 95% of their lives living on dry land, periodically going into the water around 20 minutes at a time to:
- Dampen their gills
- Store water in their shells
Doing this prevents suffocation and enables land hermit crabs to thrive in captivity.
How Long Does It Take for a Hermit Crab To Drown?
As mentioned, marine crabs don’t drown. They’re able to breathe underwater for as long as they need to. They’re at risk of other environmental factors posing a threat to their lives, such as incorrect temperatures and salinity levels.
On the other hand, land crabs can only breathe underwater for roughly 20-30 minutes. Any more than this and they’ll likely die. Juvenile or sick hermit crabs may only last 10 minutes underwater before they succumb to suffocation.
That being said, all hermit crabs are different, and we don’t know for sure how long they can survive underwater. Some can even last as long as 60 minutes before they die. They also have an innate sense of how long they can survive and attempt to get out of the water before it’s too late.
Unfortunately, keeping land hermit crabs alive is tricky because they need access to water. This means you’ll need to take preventative measures to prevent them from drowning.
How To Prevent Hermit Crabs From Drowning
It may surprise you to know that hermit crabs don’t swim. That’s why they need additional assistance escaping water so that they don’t drown. You can provide this by adding the following things to your hermit crab’s enclosure:
Ramps are the best way to prevent hermit crabs from drowning. This gives them an easy exit from their swimming pools. You can pick up plastic mesh ramps from most aquatic stores that hermits can easily grip onto.
Plastic canvas ramps are also another good option, as they don’t rust and are cheap to buy. Keep an eye on your ramps to make sure your hermit crabs can walk up and down them at all times.
Hermit crabs need external water sources in their enclosure, including two swimming pools of water. One should contain dechlorinated freshwater, while the other needs a sprinkling of marine salt. This enables hermit crabs to bathe and keep their gills moist, preventing the risk of drowning. Never use table salt as iodine is toxic.
When searching for swimming pools, choose the simplest ones you can find. While pools with multiple levels may tempt you, they’ll confuse your hermit crabs. This increases the risk of drowning.
Correct Water Depth
Don’t make your swimming pools too deep as your hermit crab could drown. They should be deep enough for the crabs to submerge themselves and their shells underwater but shallow enough not to confuse their exit.
Hermit crabs don’t grow to be very big, so you don’t need to fill the pools too much. 2-6 inches should be enough, depending on your pet’s size.
Land hermit crabs require the appropriate amounts of humidity to breathe. Most owners follow the 80/80 rule when setting up their tank, which means the:
- Humidity should be at 80%
- Temperature should be 80 degrees
This humidity introduces moisture to the air, enabling hermit crabs to breathe. You can use a hygrometer to measure humidity and a misting spray to apply more to the atmosphere. As a rule of thumb, mirror your hermit crab’s natural environment to keep it healthy.
Unfortunately, many owners lose their hermit crabs due to drowning. You must keep an eye on your hermit crabs to ensure their enclosure’s suitable and doesn’t leave any risk of accidental drowning.