Posh are now unbeaten in five matches - a well timed purple patch as a number of their fellow strugglers also continue to pick up vital points.
They lie one point from safety and just four points behind Blackpool, who could not build on their first win under Paul Ince at Watford last weekend.
Pool dominated a first half overshadowed by a serious head injury sustained by their veteran midfielder Barry Ferguson, but Ferdinand put United ahead with a simple finish in the 45th minute.
Dwight Gayle and Lee Tomlin might have added to Peterborough's advantage after half-time before Blackpool's late rally failed to truly threaten.
- Sports & Recreation