<human>:  Can the largest crustacean stretch out completely on a king-sized mattress?
<bot>: No, the largest crustacean is not large enough to stretch out completely on a king-sized mattress. The largest crustacean is the Japanese spider crab and the largest Japanese spider crabs have a leg span of just over 12 feet and the longer edge of a king-sized mattress is six feet, eight inches, so the largest crustacean is not large enough to stretch out completely on a mattress.