In the Crabitat


**If you are looking for the hermit crab dishes I make and sell, you can find them at my Etsy store. Thank you!

I’ve had a hermit crab obsession for a while now. And it actually started back in the 1990s when I lived in Florida and bought my first three. I did keep them in a big aquarium, but only provided gravel, a shallow freshwater dish, and pellets of “hermit crab food” from the pet store. I think they lived about two years. And it haunts me.

I have learned so much more about their care and feeding since that time and I like to think I’m making up for my earlier ignorance. These days, my tank is a 120-gallon (tall) with saltwater and freshwater pools, lots of climbing structures, and ten inches of sand—lots of space for them to dig tunnels and create safe molting caves. AND, I’m doing my best to learn how to breed them in captivity so that our pet hermits that we love don’t have to be captured and taken from the wild. Links to detailed records of my captive breeding attempts (by year) are below, followed by a running log from the current year.

Summer 2017 Breeding Attempt

Summer 2018 Breeding Success

Summer 2019 Breeding Success

Summer 2020 Breeding Success

BY-YEAR BREEDING STATS:

2018 Stats:

First Mating (observed): August 15th, 2018.

First (successful) Spawn (September 13th): Approximately 10,000 zoeae hatch successfully and are moved to a kreisel tank kept at 83 degrees Fahrenheit and at a salinity of 35 PPT.

Day 5, first zoeae molt into larval stage two.

Day 9, first zoeae advance to larval stage three.

Day 14, larval stage four begins, about 1,000 surviving.

Day 19, molt into larval stage five begins.

Day 24, first megalopa! (Approximately 40 megalopa get moved to the transition tank.)

Day 36, first megalopa takes a shell and walks out of the water. (Over the next two weeks, 4 are moved to the land tank, in shells.)

Day 49: Confirmed! 2 survivors make the first molt to become land hermit crabs.

Second Spawn (October 16th, 2018): About 10,000 zoeae hatch successfully.

Day 4, zoeae enter larval stage two.

Third Spawn (October 20th, 2018): Another 10,000 hatch, get placed into several small “holding” tanks and receive minimal care. Survivors are gradually added to the kreisel over the next seven days.

At this point, with two full spawns, four days apart, it becomes impossible to tell the larval stages because shedding occurs daily.

Day 23, first megalopa. Over the next two weeks, about 1,000 megalopa are moved to the transition tank.

Day 26, spot blue zoeae among the orange zoeae. Conclude, with the help of other hermit crab experts, that the blue ones must be Ecuadorian zoeae. (This is later proven to be a false assumption.)

Day 34, first megalopa takes a shell and walks onto land.

By mid-December 2018, 240 baby hermit crabs have been moved to the land tank where they are largely cared for similar to adult hermits.

January 8th, 2019: confirm, by count, that 206 have survived the first land molt to become land hermit crabs. (2 stayed hidden in shells and were accidentally left out of the tank after the counting process, so 204 is the actual survivor count, allowing for human error.)

October 22, 2019: 180 captive-bred baby hermit crabs have been successfully adopted out to brand-new forever homes. All of these first adopters have agreed to participate in a long-term study to track growth, behavior, shell preference, and coloration over time and in different conditions.

I’m so very grateful to all those who contributed supplies, love, and support. ❤️❤️

2019 Stats:

First (successful) Spawn (September 10th, 2019): About 10,000 zoeae hatch successfully and are moved to a kreisel tank kept at 78 degrees Fahrenheit with a salinity of 35 PPT.

Day 22, first megalopa! (Over the next few weeks approximately 4,000 megalopa are moved to the transition tank which is a plastic bin holding roughly 4″ of saltwater at 35 PPT and kept at 75-78 degrees Fahrenheit.)

Day 30, first megalopa takes a shell.

Day 35, first baby walks onto land. Over the next two weeks, 390 megalopa take shells and are moved to the land tank (100% sand) where they will fend for themselves.

Second (successful) Spawn (October 12th, 2019): Approximately 7,000 zoeae hatch successfully and are moved to a kreisel tank. This batch will be given minimal care in an attempt to see how many survive with fewer feedings and water changes.

Day 18, first megalopa! 930 megalopa are moved to the transition tank over the next 11 days.

Day 26, first megalopa takes a shell.

By Day 66, 336 megalopa from the second spawn have taken shells and been moved to the land tank for a total of 726 captive-bred baby hermit crabs moved to land (from two spawns) in 2019.

May 6th, 2020: A follow-up count of the 2019 spawns reveals that 633 of the 726 initially moved to land have survived ~8 months post-spawn. Of that number, .3% are XL (7-8 mm opening shells), 9% are Large (5-8 mm opening shells), 43% are Medium (3-5 mm opening shells), and 47% are small (2-3 mm opening shells).

Baby #55 moving onto land.

2020 Stats:

5-4-20 I meet fellow hermit crab keeper Kelly Kurtz and she gives me three large mason jars of zoeae that she discovered in her saltwater pool and believes to be either C. viola or C. perlatus based on brooding behavior exhibited by her female crabs.

5-7-2020 (Day Five) First day of sheds, so larval stage two begins. They don’t seem very happy, so after researching salinity in the waters off the coast of Indonesia (where I believe these crabs may be native) and finding that it is far more dilute, I gradually lower the salinity to 31-32 PPT.

5-10-2020 (Day Eight) Second sheds into larval stage three begin. They are ravenous and eat everything, but don’t appear to be especially cannibalistic. Still not appearing super happy, so I lower the water temp to 84 degrees Fahrenheit and that seems to be better.

5-13-2020 (Day Eleven) First larval stage four sheds begin, somewhat overlapping with the later sheds to stage three. I believe this will be their final stage, since by now I’m pretty convinced these are not clypeatus.

5-16-2020 (Day Fourteen) I do a full clean and count zoeae as I siphon. There are ~1,400 stage four zoeae on Day 14.

5-18-2020 (Day Sixteen) First megalopa moved to transition tank. Over the next eight days, 1,113 megalopa are moved to the transition tank. They are ravenous and eat anything I give them: frozen brine shrimp, hatched artemia, shrimp pellets, dulse, Marine Snow, and I add plenty of nannochloropsis to the water. I lower the salinity to ~30-31 PPT and the temperature to 81 degrees Fahrenheit so they don’t develop too quickly.

5-23-2020 (Day Twenty) the first megalopa take shells and walk onto land.

6-8-20 All of the surviving megalopa have taken shells and 507 have been moved to the land tank. Stay tuned! (Species STILL UNKNOWN.) Coenobita mysteriosa for now.

9-8-20 At six months of age, all C. mysteriosa are moved to the 55 gallon baby tank (to reside with the remaining 2019 clypeatus babies). It takes two weeks for all molters to resurface and be counted. A full count reveals there are only 275 survivors (out of 507). This represents my highest loss rate to-date (~46%) for any moved-to-land juveniles. I believe this high loss rate resulted from offering access to deep water pools right away. Even with exit ladders many drowned and more became trapped under the pool and expired there. There are no plans to repeat that experiment with future spawns.

9-21-20 Artemis (C. clypeatus) spawns on her own in the saltwater pool.

9-22-20 Gilda (C. clypeatus) has an assisted spawn (in a bucket with a bubbler).

9-24-20 Lola (C. clypeatus) has an assisted spawn. I this point, I have all three kreisels up and running and several tens of thousands of zoeae.

10-4-20 Saskia (C. compressus) has an assisted spawn in a bucket with bubbler, and approximately 6,000 hatch. The C. compressus zoeae are then divided among the three active kreisels containing clypeatus. Given their much smaller size, I believe it will be easy enough to distinguish compressus zoeae from clypeatus.

10-10-20 Big Red (C. perlatus) has an assisted spawn in the prepared transition tank (intended for the upcoming C. clypeatus megalopa but as yet unoccupied). The combined zoeae in the single kreisel are then divided among the two double kreisels and the C. perlatus are all placed in the single kreisel so I can better track their progress.

Across the board, this proves to be too large of a population to sustain and I see massive die-offs on or around 10-14-20. At this point, it is also unclear how many of which species remain because they have all become intertwined.

10-15-20 I begin moving megalopa over to the transition tank, where all species reside together, eventually relocating 632 mixed-species megalopa to the transition tank.

10-25-20 The first megalopa takes a shell and walks onto land (assumed to be clypeatus as they are oldest). Over the next 25 days, 131 megalopa (mixed clypeatus, perlatus, and compressus) take shells and are moved to the temporary land tank.

10-31-20 Big Red (C. perlatus) spawns for the second time, on her own, in the saltwater pool. Roughly 3/4 of the spawn is siphoned out and added to the single kreisel where I can track them more carefully this time. The rest remain in the saltwater pool within the tank, but these do not appear to survive more than a day or two at most.

11-19-20 First C. perlatus megalopa from the second spawn is moved to the transition tank, where 5 or 6 remaining stragglers from the earlier batch are still taking shells or staying in the water in shells.

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The adoption form for any of my captive-bred babies can be found here.

  If you would like to donate funds to help further the cause of sustainable, ethical, hermit crab husbandry, you can do so here:
Thank you!