The Zoo is a one-act comic opera, with music by Arthur Sullivan and a libretto by B. C. Stephenson, writing under the pen name of Bolton Rowe. It premiered on 5 June 1875 at the St. James's Theatre in London (as an afterpiece to W. S. Gilbert's Tom Cobb), concluding its run five weeks later, on 9 July 1875, at the Haymarket Theatre. There were brief revivals in late 1875, and again in 1879, before the opera was shelved.
The farcical story concerns two pairs of lovers. First, a nobleman, who goes to the zoo to woo the girl who sells snacks there. He tries to impress her by buying and eating all of the food. The other couple is a young chemist who believes that he has poisoned his beloved by mixing up her father's prescription with peppermint that he had meant for her.
The score was not published in Sullivan's lifetime, and it lay dormant until Terence Rees purchased the composer's autograph at auction in 1966 and arranged for publication. The opera is in one act without spoken dialogue, running about 40 minutes. Like Trial by Jury and Cox and Box, it has been staged as a curtain-raiser to the shorter Gilbert and Sullivan operas. Triple-bills of Sullivan's three one-act operas have also proved successful.
How Sullivan came to collaborate with Stephenson is uncertain. Just ten weeks before The Zoo opened, Trial by Jury premiered at the Royalty Theatre, with a libretto by Sullivan's more famous collaborator, W. S. Gilbert. But in 1875, Gilbert and Sullivan were not yet a permanent team. Sullivan had already written two operas with F. C. Burnand, and in late 1874 he had travelled to Paris to see one of Offenbach's librettists, Albert Millaud, although it is not known if anything came of that meeting.