Whale barnacles and whale "lice" on a mature female gray whale.
This patch is roughly 6 inches (15 cm) in diameter. Both the barnacles and the "lice" are specialized to live on whales. The barnacles are the volcano shaped objects with white circular openings. The numerous sowbug-shaped animals among the barnacles are a species of specialized crustacean that only lives on gray whales. (Similar related species are specialized to live on other species of whales.)