Larval billfish (species unknown) from sargassum weed community. Sargassum Weed is a marine plant (a brown macroalga). Two species float, unattached to the substrate, on the surface: Sargassum natans and S. fluitans. These species are found in the Gulf of Mexico, the Caribbean, and in parts of the Atlantic. The "Sargasso Sea" was named for the mats of these plants on its surface. Dense mats can form and create huge "floating islands," forming bands or mats dozens of meters in length or diameter. An entire community of wildlife has adapted to life in Sargassum weed including shrimp, crabs, and fish. The weed serves as critically important larval habitat for a number of larval fish including commercially important species such as billfish, sailfish, Mahi Mahi, Pomfret, and flying fish. These shots were taken in the Gulf of Mexico in 2010 and 2011.