Torquay dominated the first half, but failed to make the most of their territorial advantage with Kieran Charnock coming closest for the Gulls, but his header was tipped over the crossbar by Brighton goalkeeper Michael Kuipers.
The Seagulls barely tested the Torquay goal in the first period, but livened up after the break.
Nicky Forster and Liam Dickinson both went close for the League One side before Crofts broke the deadlock with a brilliant header from Gary Dicker's corner that flew into the roof of the net.
Forster again went close for the visitors, only for Michael Poke to get down and save his low shot, while substitute Kevin Nicholson saw his powerful drive punched clear by Kuipers as Torquay searched for an equaliser.
Glenn Murray could have made it two late on for Brighton, but he dragged his shot wide.