Hermit crabs are nocturnal creatures. This means that they sleep during daylight hours and are up and around at night. This doesn’t mean that you will never see them walking around during the day, but as a rule they do tend to be more lively come evening. It is believed that the reason they are this way is because it is too hot during the day where they live in the wild, and during the evening hours it is warm and humid just as they need. The other reason is due to more predators being out during daylight hours. With darkness as their ally, they are much less prone to be seen. Pet hermit crabs can be trained to come out durrng a certain time of day if played with at that same time on a daily basis, but in the wild they are more commonly nocturnal.