Misc: What is the name of the fin on a fish's back?

Questions

Which famous mystery writer created a mystery by disappearing in 1926?

Which famous mystery writer created a mystery by disappearing in 1926?

Which famous scientist's first published work was a monograph on barnacles?

Which film preceded 'magnum force' and 'the enforcer'?

Which film starring julie andrews and christopher plummer won the oscar for best picture in 1965?