Surface-living organisms of tropical oceanic waters
a - Macroneustonic (pleustonic) portuguese man-of-war,
Pleysalia pelagica, and symbiotic fish Homeus b - Macroneustonic (pleustonic) by-the-wind sailor,
Velella c - Epineustonic water strider, Halobates d - Eggs of Halobates on a leaf of sea-grass