William (“Bill”) M. Hamner, a pioneer of ethological studies of avian and aquatic organisms who changed the way we think, particularly about the gelatinous zooplankton that suffuse the world’s oceans, died on 06 June, age 84 (Figure 1). Bill’s innovative approach to investigating pelagic animals married simple observation with unconventional methods in novel situations. This work spanned a half-century, beginning when he boldly moved marine science off the deck of ships, out of undiscriminating trawls that tend to macerate specimens, away from the accessible intertidal zone, and into the blue water of the pelagic realm. Bill’s ethological approach defined much of his life’s work and took him to extreme tropical outposts, the frigid waters of the Antarctic, and the depths of the ocean, always with his life-long collaborator in science and life, Peggy Hamner.