Hydrostatic pressure emerged as a significant environmental factor in ecology and evolution during the second half of the twentieth century. Pressure is not explicitly considered, for example, in Ekman’s classic 1953 book on the biogeography of marine animals (Ekman 1953). The book, a revision of a much earlier edition, was probably completed just as the Galathea Expedition ended in 1952 and was uninfluenced by the discoveries of its scientists (Bruun 1957). ZoBell and Morita, as participants on the Galathea Expedition, showed that pressure must be considered as a significant environmental parameter affecting the distribution of bacteria (Yayanos 2000, ZoBell 1952; ZoBell and Morita 1959). Other members of the expedition found animals in the greatest ocean depths