USS San Diego photographed 28 January 1915, while serving as flagship of the Pacific Fleet. Her name had been changed from California on 1 September 1914. Note two-star Rear Admiral's flag flying from her mainmast top.
All these are animals that, in a sense, occupy the physical niche of the plants which are missing from the deeper parts of the marine environment. All are filter-feeders, straining plankton from the surrounding waters.