Humidity 

Orin (2018) in Breeding the Vampire and other Crabs (Brachyura and Anomura in Captivity) Husbandry, Reproduction, Biology and Diversity claims that a lidded enclosure with high humidity and little ventilation "can kill them within days" so he prefers not to use lids (p. 116). It is important to note that Orin attributes this rapid death to stagnant and poorly oxygenated tanks. And even more important to note is that Orin's standard set up is the most basic imaginable with a sponge for land sitting in a water feature with no live plants, except for occasionally some moss. 

This author has found no such susceptibility to high moisture or high humidity using static water features in a heavily planted vivarium with minimal ventilation and a relative humidity in the 90's. Orin's aversion to and repeated belief in his books that heavily decorated and planted tanks are only for the keepers benefit or aesthetics and all that Geosesarma need or should have is an unobstructed simple sponge-land area, maybe with moss, and a water feature compared to planted vivaria to cycle air with places for the crabs to burrow and hide show that he did not consider that plants in a planted tank can give off sufficient oxygen to prevent the tank from becoming stagnant and that he did not consider how Geosesarma have been documented to live in nature. Perhaps for him with his standard bare minimum sponge-land set ups and little new oxygen from plants was his problem all along, with the addition he was working with mainly wildcaught adults, and not that high humidity or limited ventilation kills them as a hard rule-of-thumb.

Not many animals thrive on poorly oxygenated enclosures but Geosesarma have not simply died of high humidity in naturalistic setups of this author. In many instances these more naturalistic environments that do have a higher humidity, but with soil for burrowing and water features for submerging, have instead allowed the wild caught adults to accumulate faster, regain health after shipping, and live longer lives that make it to breeding chances, compared to more basic setups. But expereinces and quality of the vampire crabs can vary.  

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