A second half header from Adam Thompson saw Blackpool crash to their sixth defeat on the bounce.
The defender guided a 76th minute header past keeper Dean Lyness as the Seasiders’ dreadful run continued.
Despite defeat Blackpool had some decent openings in the first half, with debutant Andy Little’s header crashing the bar before Mark Cullen fluffed a golden chance just before the break.
Loan man Little looked lively before he limped off with a hamstring injury as boss Neil McDonald’s gamble to play him from the start backfired.
After the break, and with the wind at their faces, it was a different story for Pool who struggled to create chances.
Southend pushed and eventually got their reward on 76 minutes when Thompson headed home from eight yards.
In the end it was another defeat, and another game which asks big questions of McDonald’s Pool squad.