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Do hermit crabs need water to breathe?

How Do Hermit Crabs Breathe? (Lungs vs. Gills)

Hermit crabs, including land-based crustaceans, breathe through gills, which must be kept moist. Terrestrial hermit crabs also have an adaptation called the branchiostegal lung.

Land hermit crabs must live in humid conditions to breathe easily. So, never allow the humidity in a hermit crab enclosure to fall below 80%, as this increases the risk of suffocation.

Terrestrial hermit crabs can’t breathe underwater indefinitely but may survive for around 20 minutes.

Marine hermit crabs can breathe underwater indefinitely, but their gills dry out on land. If you care for aquatic hermit crabs, avoid removing them from the water for more than a few minutes.

Does a Hermit Crab Have Lungs or Gills?

All hermit crabs have gills, but terrestrial hermit crabs must keep them moist. If hermit crabs are kept in arid conditions, their gills will start to close, making breathing increasingly difficult.

Terrestrial hermit crabs have evolved and developed lungs despite their reliance on gills.

As explained by Arthropod Structure and Development, most hermit crabs have a branchiostegal lung over the more familiar abdominal lung.

The branchiostegal lung is small and thin, making it easier to absorb air from the gills and pass it to the bloodstream, especially as an external shell covers most of the body.

The gills and lungs work in tandem to enable hermit crabs to breathe.

Do Hermit Crabs Need Oxygen?

According to Comparative Biochemistry and Physiology, oxygen is vital for marine hermit crabs to breathe, while terrestrial hermit crabs rely more on carbon dioxide for air.

Land-dwelling hermit crabs can spend a little time in the ocean.

Wild hermit crabs wait for a high tide and submerge in salt water for a short while. Equally, marine hermit crabs will spend time on the beachfront seeking sustenance.

Both types of hermit crabs need the right environment to prevent suffocation. Land hermit crabs can’t spend too much time underwater, and marine hermit crabs can’t spend too much time on land.

How long can a hermit crab live out of water?

Signs A Hermit Crab Is Suffocating

Suffocation is a common but avoidable cause of death in captive hermit crabs. If you decide to care for hermit crabs, you have to understand the warning signs that they’re struggling for air.

The symptoms of suffocation in hermit crabs include:

Some symptoms resemble molting the exoskeleton, but the hermit crab will eat and dig more often.

How Do Land Hermit Crabs Breathe?

Terrestrial hermit crabs are from tropical conditions and rely on humid conditions to breathe. Humidity and carbon dioxide are intrinsically linked, so the higher the humidity, the easier it is to breathe.

Captive hermit crabs must live inside an airtight enclosure, ensuring humid air is drawn through the gills and into the bloodstream by the branchiostegal lung.

Get a hygrometer for the hermit crab tank to ensure the humidity level remains appropriate.

80% is considered the optimum level of humidity. Any less causes hermit crabs to gasp for air, but too much moisture leads to mold growth on the tank walls.

Increase the humidity in a hermit crab tank with the following actions:

Hermit crabs that can breathe freely and easily will actively explore their living environment at night.

How Do Hermit Crabs Breathe Under Sand?

Hermit crabs like to burrow under their substrate. Wild hermit crabs spend most of the day buried under sand, hiding from predators and avoiding the sun’s heat.

Captive hermit crabs often sleep under the sand and hide while molting or stressed.

You may be concerned that burrowing under the sand is a suffocation risk, but this isn’t the case. Playground sand, coconut soil, and creature soil are all hermit crab-safe choices.

An appropriate substrate won’t collapse and lead to suffocation. By building a sandcastle, you can tell if the substrate is appropriate and safe for hermit crabs.

To be extra cautious, wet the substrate before building the sandcastle and ensure this doesn’t alter the texture. For example, wet potting soil turns to mud and restricts breathing.

How Do Hermit Crabs Breathe Underwater?

Land hermit crabs can’t breathe underwater but can hold their breath temporarily when submerged.

While terrestrial hermit crabs spend time in the water to bathe and fill their shells with drinking water, they can’t stay underwater indefinitely.

Minimize the risk of drowning with these safety precautions:

  • Use shallow vessels with enough to submerge the body, as hermit crabs can’t swim.
  • Ensure hermit crabs can quickly get in and out of the water with the addition of ramps or nets.
  • Reduce the risk of mite infestations, driving hermit crabs to spend more time in the water.

Most hermit crabs can hold their breath for around 20 minutes.

Do hermit crabs have gills or lungs?

How Do Marine Hermit Crabs Breathe?

Marine hermit crabs breathe using a scaphognathite (a thin appendage at the underside of the mouth).

The scaphognathite draws water to the gills, and oxygen is extracted from the water and passed to the bloodstream. As aquatic hermit crabs rely on oxygen, not carbon dioxide, it’s expelled through the mouth.

Marine hermit crabs need specific conditions to breathe easily:

  • Use saline water, not tap water, because it contains chlorine and heavy metals.
  • Water pH shouldn’t fall below 8.0 or exceed 8.4.
  • Water gravity should fall between 1.021 and 1.028.
  • Nitrate levels shouldn’t exceed 10 parts per milligram.
  • Don’t allow the water temperature to fall below 72OF or exceed 78OF.

Adhere to these guidelines so marine hermit crabs can breathe freely and easily.

How Long Can Hermit Crabs Breathe Underwater?

Marine hermit crabs can breathe underwater indefinitely when their environmental needs are met. Captive marine hermit crabs can remain submerged in water 24/7.

Can Hermit Crabs Breathe Out of Water?

Marine hermit crabs can breathe out of the water as long as their gills remain moist. Once the gills dry out, the hermit crab will struggle to breathe.

This happens much faster in marine hermit crabs than in their land-based counterparts. As a result, removing aquatic hermit crabs from water for longer than a few minutes is inadvisable.

The only occasion you need to do this is while the aquarium is cleaned. This can take 24 hours to complete, so you need a second tank to keep them in temporarily.

Whether you are using a bathtub, sink, or a second aquarium, the usual caveats apply. The water must be between 72–82OF, have a pH between 8.1 and 8.4, and a salinity of 1.021–1.028.