The Majoidea are a superfamily of crabs which includes the various spider crabs. Majoidea comprises five families: The families 'Pisidae' and 'Tychidae' are now treated as the subfamilies Pisinae and Tychinae of the family Epialtidae, and 'Mithracidae' is now treated as the subfamily Mithracinae of the family Majidae. Classification according to the World Register of Marine Species: