How Big Will a Hermit Crab Get?

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‘How old’ is an oft asked question and hard to answer. Lifespan is similar. Both depend on a lot of things, like what they eat, how much they exercise, how often they shed their feathers, the order in which they are nested, the species of bird, and the availability of seashells. I’ll talk about a few of them in this article and end with some tips on how to get a rough idea of your hermit crab’s size and age. Thanks a lot to Carol of CrabWorks for letting us use her beautiful photos and for being such an inspiration to all of us!

Most of the time, what and how much a hermit crab eats and drinks determines how fast it grows. A land hermit crab’s growth cycle is based on a process called moulting, which is often set off by how much it eats and drinks. The body grows within the hard outer skeleton. Just as when we are young and our feet are growing, but the shoes do not. When the tough outer shell (or shoe in this case) no longer fits and squeezes your bigger foot, we change shoes. So do shoes feel bad when your body keeps water in, like when you’re traveling or after eating salty foods? Growing feet can cause the material to stretch, which can cause weak spots (often around glue lines) to come apart.

“Usually, animals that are about to moult go into their burrows with their bellies very full from food reserves. After moulting, the animal eats its exuviae, which contain organic materials and calcium salts that the new skeleton needs. Very little is known about how Coenobita moult.” It is said that Coenobita clypeatus hides during the process, which takes place mostly in the shell (de Wilde, 1973). Several days before the moult, there is a noticeable drop in activity, and after ecdysis, the exuviae are placed right in front of the shell’s mouth (A). W. Harvey, pers. comm. ). This process called calcification shapes the new soft skeleton of the chelae and other walking legs to fit the shape of the shell. If the animal gets very big, it might not fit inside the old shell anymore, and it might need to quickly switch shell sizes to keep from losing water and being eaten. We don’t know anything about the balance of calcium, how it is stored during the moult, or how much Coenobita grows. Coenobita clypeatus grows up to 500 g if large-enough shells are available” (Greenaway, P. 2003 p. 21) Land Hermit Crabs that eat a lot of calcium, fiber, chitin, and other nutrients will often shed their shells much more quickly. This process slows down as the crabs get older or don’t have access to bigger seashells. It takes longer for a crab to shed its shell when it is in a seashell because it is tight and doesn’t have many other options.

Exercise is known to increase hunger, and thus will affect the rate of moulting. In the wild, land hermit crabs have been known to walk many miles a night, and graze on foods along the way. It would depend on location as to the amount of exercise and grazing a hermit crab will do. We can full fill the need to walk by providing a plastic hamster wheel in the crabitat. It is important to provide a multitude of climbing surfaces as well.

Scientist Mike Oesterling of the Virginia Institute of Marine Science has noted this in Blue Crabs.

“In the summer months, food availability has a major affect on shedding activity. If a crab does not satisfy the physiological need to shed (increased muscle tissue, body cavity ‘cramping’, etc. ), it will not enter the molting cycle. In other words, if it doesn’t get adequate nutrition it’s not going to grow. ” (Oesterling, M. 2003).

Hermit Crabs are social animals, and as such, there is usually a ‘pecking order’ among groups or colonies. As with many other animals and plants, when food is scarce, there is a “pecking order” among hermit crabs. Hermit crabs need a variety of protein- and calcium-rich foods, places to hide, room to dig down to shed their shells, different-sized seashells, water, and ocean water.

If a crab is ‘top crab’ than it would get the most food, like with puppies and seagulls. In the crabarium, we see this on a small scale when hermit crabs fight over the food bowl or their favorite place to hide. I have often watched my jumbo hermit crabs fighting for access to the salt-water bowl or treat dish. They often fill the bowl all the way to the top and push other hermit crabs out of the way to protect their right to eat first.

Hermit Crabs grow through moulting. A hermit crab won’t look very different before and after its moult, but after ten or twenty years, it will be very different. If you want to know how old something is, you can also look at the antennae and the little “teeth” on the cheliped or grasping claw.

Carol of CrabWorks has had the same two hermit crabs for twenty-six years. On her photo page, she shows how much they have grown over 25+ years in captivity. Carol believes Jonathon and Kate would have grown more than they have in captivity. Not only are her crabs limited by the size of the seashells they can find, but the way they roam around her sunken living room at night is nothing like how wild crabs do it. (Carol lives in Florida which is the native habitat of C. clypeatus so she is able to allow her hermit crabs to roam outside of the crabitat. ).

Sheep in the wild are known to walk miles every day, so they need to eat more to stay alive. That being said, they might not get the tasty foods they eat in captivity. Instead, they would eat shells, wood, and other “normal” foods like dead animals, fish, meat, and fruit that they find on the beach, in the mangroves, or in the forest.

Jonathon Livingston Crab and Kate in 1977, a year after getting them from two different pet stores

Jonathon and Kate in 1998, eleven years on and a toasty brown colour.

The different kinds of food Carol gives her hermit crabs are meant to be like the food they would find in the wild. Their favourite is Brown Oak Leaves,.

“I usually pick up the fresh brown leaves from a sidewalk, not from the ground. I do inspect them for bugs, mold, and weird spots.

There are so many available that choosing is easy”.

The leaves may have helped Jonathon and Kate get their beautiful dark chocolate color, but that’s just the beginning of the great food her hermit crabs eat every day.

For calcium, Carol gives them “boiled eggshells about once a week. They like brown oak leaves, spinach leaves, a little lettuce, and tree bark that has been boiled or microwaved (but not cedar or pine). They just love bark and oak leaves. These too: bananas, apple slices, scrambled eggs on Saturday, a variety of dry cereals (including Kashi), occasional cookies. I just keep changing and trying new foods. They don’t like the same foods all the time, or even two nights in a row! I sprinkle sea salt on their food a few times a week, and I’m trying it out in a second water dish right now. I’ve already seen them drinking it. ”.

When a crab moults, they often regenerate any limbs or body parts that were lost between moults. After the first few moults, the new limb is usually much smaller than the old one. It takes a while for it to grow to the same size as the old one. This is one reason why a hermit crab’s cheliped size doesn’t always show how old it is.

Size and Aggression, Competition for Shells

Over the last two years, I’ve seen more than thirty jumbo Australian land hermit crabs. They really opened my eyes to how larger hermit crab colonies deal with aggression and social order. Some of the crabs were in seashells that didn’t fit right or were broken. They were found in the wild. Seashell fights were rife and more than a few hermit crabs killed for their shell.

It makes you understand how valuable it is and what “survival of the fittest” really means. The faster the hermit crabs found a new or different modified seashell to protect themselves, the faster they settled down and became important in the group. Many Hermit Crabs that had a seashell that didn’t have any obvious flaws stayed in it for a year or more, even when they had more than one hundred (100) to choose from. They liked Tunna shells, Turban shells, Fox shells, whelk shells, and different types of Murex shells. Smaller hermit crabs love the Nerite shells, which are found in large proportions along the coast of Australia. Other popular shells are: Thais (rock shells) and Turban shells.

Being around older, bigger hermit crabs helped me understand why bigger hermit crabs aren’t common in many places around the world. As it gets harder for hermit crabs to find big shells, they have to fight harder to stay alive. If they can’t find a light seashell with enough room and watertight properties, they will soon outgrow their current one, become dehydrated from not having a seashell that fits, or be attacked. Either way, their chance of survival is limited. This could be the reason why many larger hermit crabs that are kept as pets don’t seem to get much bigger after a certain age. They will be more likely to grow if they can eat right, work out regularly, and have a variety of seashells of the right sizes and shapes. They might not be able to grow as much if they have to stay in the same seashells for years on end because of the size or shape of their seashell.

I usually sort hermit crabs by the size of their cheliped (grasping claws). Older crabs have bigger claws, but as we already talked about, this isn’t a very scientific way to do it because hermit crabs lose their claws when they’re stressed and it can take them a while to grow back to their original size.

BBC One video on hermit crab housing and the chain reaction a single shell change can trigger:

What’s Inside a Hermit Crab Shell?

FAQ

How big do pet store hermit crabs get?

How long does it take for a hermit crab to grow full size?

What is the maximum size of a hermit crab?

Do hermit crabs like being held?

How big does a hermit crab get?

Land pet hermit crabs range between 0.5 inches and 8 inches in size. The smallest species is the Ecuadorian hermit crab, while the biggest is the Indo Hermit Crab, which can grow up to 8 inches. The Coconut crab is the largest hermit crab measuring up to 1 meter (40 inches), but very few people keep it as a pet.

What is the largest hermit crab?

The world’s largest hermit crab is coconut crab which can grow more than 40 inches. This is a land crab. There is also a big marine hermit species called giant red hermit cr-ab. Your email address will not be published. Hermit crabs can grow up to 5-6 inches long.

How big should a hermit crab tank be?

Some smaller species such as the Ecuadorian hermit crab can be kept in a tank as small as 10 gallons, but if you plan to keep a large group of them, you will need to increase the tank size accordingly. Hermit crabs in captivity don’t typically grow larger than 8 inches in size, with many species only reaching around 1 to 2 inches.

How big should a hermit crab enclosure be?

The size of the enclosure will depend on the species, but a 20-gallon-long aquarium is a good starter size for most hermit crabs. Some species such as the Caribbean or Strawberry hermit crab need a bigger enclosure since they can grow to 6 inches.