24 hours. Crabs are cold-blooded animals and can tolerate low temperatures. Therefore, crabs will turn on their self-protection mechanism when the temperature is low. Crabs will be in a state similar to dormancy. After being frozen for a short period of time, they can last for several days without dying. At the same time, low temperature can inhibit the activity of fungi and parasites in crabs, delay the degradation of crabs' own proteins, and freeze and preserve crabs. It has almost no impact on the nutritional content and taste of crabs, so they can be eaten with confidence.