Fluker's Hermit Crab Habitat Night Time Bulb, 60-watt (3 Pack) 3 Pack of Fluker's Hermit Crab Habitat Night Time Bulb, 60-watt Use Fluker's thermometer and hygrometer inside your crab's enclosure to make sure your crab's environment is the correct temperature and humidity Bulb allows you to observe your hermit crabs at night since they are nocturnal! 3500 hours lifespan