Being slow and clumsy swimmers these fish developed an ability to inflate their stomachs and fill them with water, turning themselves into an almost inedible ball several times their normal size. Some, like this example, were also covered with a coat of long sharp spines. All pufferfish contain tetrodotoxin which is lethal to both other fish and humans. There is enough toxin in one fish to kill 30 adults and there is no known antidote. In some countries however, like JApan, the meat is considered a delicacy.