According to Baidu Health Network, crabs can't be eaten the next day after being left overnight, because crabs are scavengers, and many bacteria, microorganisms and parasites will breed in crabs. After the death of crabs, these bacteria and microorganisms will multiply and secrete a lot of harmful substances, which may lead to food poisoning, gastrointestinal infection, abdominal pain, diarrhea and even systemic poisoning.