Hydroids from Rocas Alijos

Abstract

Knowledge of the hydroids of the tropical and subtropical northeast Pacific Ocean is based almost entirely on extensive collections made by the Allan Hancock Pacific Expeditions between 1932 and 1938, and studied by Fraser (1938a,b,c, 1939, 1948). Those collections, undertaken during cruises of the Velero III, included hydroids from coastal areas between Peru and the west coast of the United States, as well as from the Galapagos Islands, the Islas Revillagigedo, and other oceanic islands of the region. Excluding the fauna from temperate waters off Peru and the United States west coast, a diverse assemblage comprising nearly 300 species of hydroids was reported by Fraser from the region. Of these, 107 species were identified from the oceanic islands offshore (Fraser, 1948).