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can hermit crabs regenerate eyes?

Do Hermit Crabs Eyes Grow Back? (Missing + Lost Eyes)

Hermit crabs have the ability to regenerate lost or damaged tissue. They frequently shed limbs, growing replacements when they next molt.

However, replacing lost or missing eyes is a more complicated procedure.

Hermit crabs have corneal lenses in their eyes that reflect light. These are replaced during every molt. However, the severance of an eyestalk is more problematic.

Hermit crabs regenerate eyestalks, although this can take 2-3 molts. Whether the eye also regenerates depends on the severity of the ocular damage during separation.

Hermit crabs with one or two missing eyes still enjoy full lives. Hermit crabs are much more reliant on antennae than eyes for negotiating the world around them.

Do Hermit Crabs Use Their Eyes?

All hermit crabs have two eyes, which are located on stalks that protrude from the head. Behavioral Processes explains that hermit crabs can differentiate between colors, but shapes are more problematic.

Coupled with the use of antennae to aid the negotiation of terrain, this suggests that vision is not a primary sense for hermit crabs. Perhaps this is due to the complex physiology of the eyes of hermit crabs.

As per the British Journal of Ophthalmology, hermit crabs have compound eyes. The eyes of hermit crabs are divided into individual ommatidia, which resemble tiny hexagons. This creates a kaleidoscopic field of vision, similar to that of an insect.

Every one of these ommatidia has an independent corneal lens, which is replaced every time the hermit crab molts. This lens reflects light, which helps hermit crabs see at night. Hermit crabs can see in even the dimmest of light, often blinded by intense illumination.

If you watch your hermit crabs, you will see antennae twitching constantly. These appendages aid hermit crabs in feeling – and smelling – what is nearby. This suggests that, while hermit crabs use their eyes, they do not rely upon them.

Can Hermit Crabs Hurt Their Eyes?

Hermit crabs can injure their eyes. Unless the issue is something serious, like a missing eye, it can be difficult to tell. As discussed, hermit crabs are unlikely to become drastically clumsier when experiencing vision issues.

You may find that your hermit crabs have a glazed, milky look in their eyes. This can resemble the impact of a cataract in a mammal. Don’t worry because it’s a common symptom of hermit crabs preparing to molt.

As discussed, hermit crabs shed their corneal lenses while molting. For this to happen, the lens needs to toughen up. From there, it will drop out and regenerate during the molting process. Other signs to look out for include:

  • Eating, drinking, and bathing more.
  • Digging, especially after spilling water.
  • General lethargy and not interacting with other hermit crabs.

If you spot these behaviors in one of your hermit crabs, remove it from a tank and temporarily rehome it alone. The hermit crab will conclude its molt after a couple of months, rejuvenated corneal lenses and all. It can then be restored to the main aquarium.

If your hermit crab does appear to be struggling to see, ensure the habitat contains saltwater. An absence of saltwater impacts the effectiveness of the antennae, especially the sense of smell. This is likelier to cause greater hardship than any restriction of eyesight.

can hermit crabs hurt their eyes?

My Hermit Crab Lost an Eye

If your hermit crab has a missing eye, you will understandably be concerned. Hermit crabs continue to live a full, happy life with one or both eyes missing.

All the same, it is advisable to learn why your hermit crab is missing an eye. The first thing to assess is whether this has always been the case. Some hermit crabs are born with eyes missing. This is a genetic mutation that could impact any animal.

In such cases, the hermit crab will not suffer any ill effects. These hermit crabs have long adjusted to living without the benefit of eyesight. They are even more reliant on antennae and tiny hairs on the legs for sensory stimulation.

If hermit crabs are losing eyes overnight, it’s more worrying. You will need to pinpoint what has happened. In times of stress and duress, hermit crabs shed limbs. This behavior rarely stretches to eyestalks, though. It is likelier that the eyestalk was willfully severed.

This may have been done by the hermit crab itself or a tankmate. Discovering what happened will help you prevent the same fate from befalling the second eyestalk, or other hermit crabs.

Aggression from Other Hermit Crabs

Hermit crabs are largely docile. They are social and like to live in groups, so home as many hermit crabs together as you can. The more company hermit crabs have, the happier they are. They will become a family.

Unfortunately, families sometimes squabble. Hermit crabs are no exception. Hermit crabs will occasionally come into conflict and may even attack each other. These disagreements can arise over territory, mating rights, food, or, most commonly, shells.

Hermit crabs try to settle their differences calmly and equitably. All hermit crab colonies obey a social hierarchy, with dominant crabs rarely meeting resistance from subordinates. A stubborn refusal to respect the pyramid can lead to aggression, though.

On the rare occasion that hermit crabs fight to injure, eyestalks are an easy target. These protruding stalks and thin and brittle. Hermit crab pincers, meanwhile, generate impressive force. It will not take much to separate an eyestalk from the head.

This will bring the conflict to a rapid end, but at what cost? This will be distressing for the victim of the assault. Hermit crabs also remember their tankmates. The scent of this aggressor will be a constant source of stress for the newly one-eyed hermit crab.

If you see pincers start to fly in a hermit crab fight, separate the pugilists. After calming down, these two crabs will likely return to co-existing in peace. This does not prevent hermit crabs from losing eyes, though. Sometimes, they sever their own eyestalks.

Foreign Objects

Hermit crabs spend a lot of time buried under their substrate. This means they may get foreign objects trapped in their eye. This could be a piece of sand or soil, or even a small insect. Humidity and warm temperatures often attract lodgers to an aquarium.

Most of the time, hermit crabs will deal with this themselves. Ensure your hermit crabs have access to two pools of bathing water. One of these should be unchlorinated freshwater, the other mixed with saltwater. Hermit crabs will submerge in these daily.

The primary purpose of this activity is to keep the gills moist. This makes it easier for hermit crabs to breathe. It also doubles up as a bath, though. This will help hermit crabs rid themselves of clinging substrate. That includes foreign objects in the eye.

If bathing does not help, the hermit crab will become increasingly frustrated. Just because hermit crabs do not rely on vision, they will not enjoy a constant pain in the eye socket. If the problem is not rectified, the hermit crab may sever its eyestalk.

This is a desperate measure, so try to avoid letting things progress this far. Encourage your hermit crab into bathwater regularly and watch for any strange behaviors.


Of all the insects that move into a hermit crab enclosure, mites are the most troublesome. Various species of these tiny bugs can set up home in your aquarium. As mites breed and lay eggs at a rate of knots, they multiply in the blink of an eye.

Parasitic mites will attach to the legs, abdomen, and eyes of hermit crabs. The hermit crab will attempt to kill these invaders by bathing in saltwater. If that does not work, they will start to sever appendages. Legs are common, but eyestalks may also be removed.

If you spot mites giving your hermit crabs a hard time, take action before your pets take matters into their own hands. Manually bathe the hermit crabs in saltwater and rehome them in a temporary enclosure.

While the aquarium is empty, it needs a complete deep clean. That means removing everything inside and thoroughly washing then air drying all surfaces. The substrate should be replaced, or at least oven-baked, and any accessories boiled in water.

After this, you can return your hermit crabs to their newly clean enclosure. This will now be mite-free, ensuring that your crabs will not feel the need to mutilate themselves.

Excessive Light

As hermit crabs are nocturnal, they rely on darkness to manage their circadian rhythms. When the sun goes down, the temperature drops outside and darkness descends, hermit crabs automatically start to wake up.

We mentioned earlier how the eyes of hermit crabs are equipped to respond to the smallest amount of light. This is all that hermit crabs want and need. If you apply a lamp to an enclosure at night, your hermit crabs will grow distressed. It’s too much stimulation.

Certain times of year will see more natural light than others. This will be reflected in the sleep-wake cycles of hermit crabs. They’ll likely rise later and retire to sleep earlier. During the winter, the opposite will happen.

Attempting to work around this can lead to drastic action from hermit crabs. These animals need at least 12 hours of darkness a day. If this is not available, they will make it so. Initially, this will involve hiding – either in the shell or burrowed under the substrate.

No hermit crab can hide all day. Eventually, they’ll need to eat, drink, bathe and exercise. If the hermit crabs are too overwhelmed by light to do so, they can sever their eyestalks. They’ll make do with other senses.

hermit crab lost eye

Can Hermit Crabs Regenerate Eyes?

If your hermit crab has lost an eye, you will want to know if they regenerate. Hermit crabs may not rely on eyesight but surely miss it. Humans do not negotiate the world by smell, but a blocked nose impacts our quality of life.

As previously mentioned, the lenses of a hermit crab cornea regenerate with every molt. In the case of eyestalks, it’s a little more touch and go.

As per The Biological Bulletin, hermit crab eyestalks can regenerate. Scientists transplanted limb tissue into empty eye sockets of hermit crabs. Limbs regrew in this area, most notably pincers.

This suggests that eye stalks can regenerate. This may take multiple molts to happen completely. Some hermit crabs will attempt to bring on molting earlier than anticipated to aid this process. Eye stalks are only half the battle, though. Can hermit crabs regenerate their eyes?

This depends upon the extent of the damage. If the eyestalk is hollow, the eye will not return. Hermit crabs regenerated damaged tissue, not grow entirely new body parts.

If there is enough of the eye left in the socket, your hermit crab may eventually enjoy vision again. This may take several molts over a period of years, though. The more time your hermit crab spends in the dark, the more it will molt.

Hermit crabs have delicate eyes that are easily damaged. This may be by accident or design. A missing eye is not the end of the world for hermit crabs. They function well with their other four senses. All the same, nobody wants hermit crabs to suffer. If you spot something amiss with the eye sockets of your hermit crabs, intervene before it’s too late.