Our crabs are named Chuk and Pukrs (Puckers). Yes! One of our crabs switched houses shortly after we got home. We haven't seen much action since and believe they may be too cold. Overnight we tried a lamp with an incandescent bulb. It warmed the tank a couple degrees but our house is cold so I don't think it was enough. We went today and purchased a heater. Hopefully they are more actie tonight.