Issued in Sheets of 20 easy to use, Self Adhesive Forever stamps will always be valid for first class postage even if rates change Celebrate the wonder of sharks stamps feature realistic images of five species that inhabit American waters. This issuance celebrates the wonder of sharks with a pane of 20 stamps featuring realistic images of five species that inhabit American waters: The mako shark, represented here by a shortfin mako (Isurus oxyrinchus); The whale shark (Rhincodon typus); The thresher shark, here a pelagic thresher (Alopias pelagicus); The hammerhead shark, this one a scalloped hammerhead (Sphyrna lewini); and The great white shark (Carcharodon carcharias) On the selvage, the stamp image of the great white shark is repeated at the top of the pane. The background blue color deepens in shade as one looks down the pane, evoking inky ocean waters barely penetrated by sunlight.