HCA: Hermit Crab Association

Hey everyone!

I’ve been a long time lurker on the forums, but this is my first post. I’d like to introduce you all to the newest love of my life; Oliver, my baby coconut crab! He arrived 48 hours ago with a weight of just 25 grams.

His current enclosure specs:

120 gallon aquarium with dimensions of 48”x24”x24”,

~10” of substrate (3 fifty pound bags of playsand, 48 quarts of eco earth, 30 pounds of organic potting soil (without pearlite) wetted down to proper moisture with MSW)

Various types and thicknesses of logs/branches (local and exotic)

Mixed species hardwood leaf litter (local and exotic)

6 quart freshwater and MSW pools with sponge filters

Humidity range of 83-90 percent

Temperature of 83-86

With the exception of substrate composition and enclosure size, he is essentially receiving what would be required by the “exotic” hermits (straws, blues, indo’s etc.).

I’m not sure if this is the right place, but I was wanting to create a sort of “diary” of his progression. There’s such a limited amount of information on the keeping of this species in captivity, I’m trying to add as much as possible to the collective knowledge base.

I’ll be tracking and taking notes every step of the way. If anyone has any ideas on additional observational note taking/things I should be tracking that could prove useful, I’d love to hear them! I’ll be setting up a webcam in short order, so I’ll be able to make nightly observations.

Pardon the poor photo quality. I snapped a couple pics during his initial weigh in immediately upon arrival, and I wanted to keep stress to a minimum.

I hope it goes well! Thanks for sharing.

I haven’t seen many keepers try coconut crabs outside of Asia. I don’t know how well they do in captivity but I hope you have a plan for when it gets bigger


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Jaydick484 wrote: ↑

Sat Jun 22, 2024 8:33 am

I hope it goes well! Thanks for sharing.

Thank you! I’ll be posting updates regularly.

JoeHermits wrote:I haven’t seen many keepers try coconut crabs outside of Asia. I don’t know how well they do in captivity but I hope you have a plan for when it gets bigger


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You’re absolutely right. There aren’t many keepers far from their native range. They don’t get exported very often, and when they do, the people who buy them seem to purchase them as more of a novelty than as an actual pet. Much like hermit crabs, they end up receiving improper care, and perish in short order.

Thankfully with Oliver being so small, he should be able to live comfortably in his current enclosure for several years. I’m expecting him to molt maybe 2-3 times a year at his current size, but again, there’s really no literature to back this assumption, so it’s all going to have to be observational note taking on my end.

That being said, when he inevitably outgrows his 120, he’ll be getting quite a large upgrade. Custom Reptile Habitats offers a PVC enclosure measuring 8’x4’x6’, which I believe (with a few modifications) would be an excellent next enclosure.

Nice. The San Diego Zoo had theirs in an enclosure of similar size for less than a year before transferring to a larger enclosure, but I think their crab was also a little bigger


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JoeHermits wrote:Nice. The San Diego Zoo had theirs in an enclosure of similar size for less than a year before transferring to a larger enclosure, but I think their crab was also a little bigger


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Oh yes, their crab Kenny was about 50 times larger when they acquired him in 2014. He was about 1,200 grams compared to Oliver’s 25 grams!

I actually went to see him at the San Diego zoo last January, but he was unfortunately down for a molt. I wasn’t able to see him, but was able to see how they have designed his enclosure.

Either way, it’ll likely be years and years until little Ollie is the size Kenny was back in 14’. I’m guessing I’ll be able to get ~3 years out of the current enclosure, and likely twice that out of his next upgrade. However, I’m not on any kind of time crunch. If he ends up outgrowing his 120 by the end of the year, he’ll be getting an upgrade!

Here is dinner for night #5 (all organic/wild collected)

Raw wild shrimp
Red bell pepper
Fuji apple
Puffed buckwheat
Assorted dried wildflower blend
Pre-made hermit blend (just2oldcrabs mix)
Snake shed (captive specimen)

Just wanted to make an update on Ollie’s progress; he has successfully molted!

He was kind enough to make his molting chamber right at the bottom of the tank (though it was at a terrible angle for photos) so I was able to make daily checks on him. His molting timeline is as follows:

-Witnessed a large uptick in both saltwater and food consumption from July 14th through the 17th
-Went down on July 18th
-Molted August 15th
-Molt completely consumed August 23rd
-Emerged, fed and consumed both fresh and saltwater August 30th

In total, it took him 28 days from burying himself to begin molting, and 43 days from going down, till re-emergence. Visually, I’d say he’s grown 25/30%, but I’ll give him a while to regain his strength before the next weigh in.

After 3 months of care, I’ve made several behavioral observations, and notable dietary preferences. Thus far, he has proven to be completely nocturnal. Lights are on a timer and go off at 9pm, and he won’t emerge from his network of tunnels until at least 35-45 minutes after lights out. I’m hoping as the years go by and he becomes more accustomed to both captivity and my presence, he’ll start making trips above ground during daylight hours. At the very least it would make photography an heck of a lot easier! All observations are currently made with a red LED headlamp so as not to disturb him. Any white light shining either on or near him causes him to bolt (remarkably fast!) back to one of his tunnels. On the topic of tunnels, he is an absolute bulldozer. Think hermit crab and multiply it 10 fold. He has at least 6 entrances/exits dug throughout the enclosure spanning the entire length, and God only knows how convoluted the network actually becomes underground. He is also constantly rearranging. Tunnel entrances come and go day by day. All said and done, I’m quite pleased with the substrate mix I came up with. It seems to be able to hold all of his burrows with ease, and maintains the 85-90% humidity I’m aiming for.

He has a definite preference for protein, nuts, vegetables and high fat, low processed oils (coconut, salmon, walnut etc.). Fruits, with the exception of shaved coconut and goji berries, are all but ignored. Raw meat with the exception of shellfish is also generally left untouched. “Favorite” food items so far seem to be any kind of shellfish, fish, beef, poultry, pork, dried insects, salmon oil, peanuts, popcorn, kernel corn, peas and dried kelp. I have however noticed that if popcorn is offered, he will tend to single out just that and leave everything else untouched.

I purchased a “mega bundle” of foods from CrabcuisineCo which gives me a great diversity of foods to choose from. Almost everything is a mix of between 15-20 different ingredients. He doesn’t get the same mix more than once every two weeks in order to ensure proper nutrition as well to avoid him picking “favorites” and ignoring other, potentially more nutrient dense foods.

Overall, he’s been an extraordinarily rewarding captive so far. It’s going to be great fun getting to watch him grow and see his individual “personality” start to show.

The photo with the red light is right after he finished his shed, and the other pictures are what I was able to take this morning before the light scared him back down one of his many holes.

Pardon the picture quality. Again, everything I’m doing is in an effort to keep external stressors to an absolute minimum.