Tapp was a restricted free agent, who signed his one-year tender to be one of Seattle's pass rushing options.
A second-round pick of the Seahawks in 2006, Tapp played in 16 games last year with 49 tackles, 2.5 sacks and a forced fumble. He has 18 sacks in his four seasons with Seattle.
On his Twitter account, Tapp said "it is truly a blessing to have a job doing what I love to do. Always appreciating my opportunities."
Grant started all 48 games during his three seasons in Seattle and has started 144 consecutive games. Grant had 78 tackles and three interceptions last season.
Grant, 31, was scheduled to make $4 million next season.
Martin, 27, played eight games in 2009 for St. Louis. Before joining the Rams, he spent three seasons in Green Bay. He has 58 career catches for 848 yards and six touchdowns.
Seattle also released running back Tyler Roehl and long snapper Matt Overton.
Copyright 2010 by The Associated Press