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Heat-bulbs-for-hermit-crabs, favorite answer in the past, it was though that hermit crabs were nocturnal and providing lights could be stressful for the crabs. however, low wattage and/or special night light bulbs are a good.... Hermit crabs don't need an elaborate home, but the appropriate temperature and humidity are vital to their health. land hermit crabs come from warm tropical climates and, therefore, they need a warm, humid environment to survive., with the glass between the light and hermit crabs. a 15 watt bulb can be used for lighting purposes, however the ambient with higher wattages you may notice a problem with keeping the humidity within the 72-82% range.