Summer 2020 Breeding

5-3-2020 A friend and fellow hermit crab owner texted late at night to tell me she had zoeae in her saltwater pool and no time to try to raise them, would I meet her and take them off her hands? They were most likely an exotic species because she had seen viola and perlatus females exhibiting brooding behavior the night before.

Have zoeae, will travel.

5-4-2020 We both slept on the decision and when the zoeae were still alive the next morning, quickly figured out a makeshift setup to transport the zoeae for five hours (2 1/2 each way). I started a jar of brine shrimp eggs for hatching, got my foods prepared, and set up the five gallon tank for filtered, heated exchange water. She bought three large Mason jars, an electrical converter for her car, and used an air pump and a bubbler with splitter, then surrounded the bottles with hand warmers and placed them in a box on the seat beside her with the seat warmer on. It was May, but a very cold day, about 41 degrees and rainy, so we were really pushing it.

I fed them some Marine Snow for the ride, got them home to my kreisel (which had been set up already in case my perlatus dropped eggs) at 5pm on the 4th and starting feeding right away–Instant Baby Brine Shrimp–and boy were they hungry! To start with, I kept their water at 86 degrees Fahrenheit and 35 PPT salinity.

5-7-2020 (Day Five) First day of sheds, so larval stage two begins. They don’t seem very happy, so I research salinity in the waters off the coast of Indonesia (where I believe these crabs may be native) and find that it is far more dilute so 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. At this writing, 42 have been moved to the land tank with many more in the queue. Stay tuned! (Species STILL UNKNOWN!) Coenobita mysteriosa for now.

6-8-20 All of the megalopa have now taken shells and been moved to land. 507 are in the land tank now, though I have already seen some losses, so I know that number will go down.

7-26-20 A partial count (all above-ground mysteriosa babies during a two-day period) showed 253 survivors. I have to believe there are more survivors below ground molting, but I don’t have time to wait for them to surface before moving the others back, so we’ll just say 253 confirmed, with more survivors likely but uncomfirmed.

8-1-20 I am starting a habitat experiment with these babies. I am still holding out hope that they will turn out to be violas, although all of the ID experts out there are telling me these are more clypeatus (based on photographs). It doesn’t jibe with the fact that they came to land sooner and had one fewer larval stage than clypeatus typically do, but science means leaving unknowns unknown until such time as they can be confirmed, so mysteriosa they will remain for at least a little longer. The habitat experiment involves making their land tank a bit more like a mangrove mudflat. I’ve ordered mineral mud (the kind used in refugiums), live sand, mangrove propagules and some tropical moss slurry that I’m trying to culture onto some old wood pieces that I have on hand. So far, I’ve offered the mineral mud in a dish, wet, and they have really been digging it. I can’t tell if they’re getting moisture from it, eating it, or just soaking, but they are definitely hanging out there for extended periods. The mangroves are rooting in a separate container that I will be adding once they appear to be comfortably established.

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.