Try not to eat the frozen hairy crabs, because the oxyacid in the frozen hairy crabs will decompose to produce histamine, which is a toxic substance. With the extension of death time, more and more histamine is accumulated in the crabs, and the toxic gas is getting bigger and bigger. Even if the crabs are cooked, this toxin is not easy to be destroyed. Therefore, eating the dead hairy crabs is harmful to people's kidneys. It is recommended to eat them alive.