Oceanic mantas Manta birostris are mostly pelagic creatures, swimming far out into open ocean. Reef mantas Manta alfredi stay mostly around reef systems, moving around seasonally. They can be found in tropical and subtropical regions of the Pacific, Atlantic and Indian oceans within 30 degrees north and south of the equator.
The resident reef mantas of Palau also regularly come into the lagoons in very shallow water, and during the months of September to May each year, the mantas gather in larger numbers to mate and give birth around channel mouths. Large feeding aggregations of over 70 mantas have been observed. Mantas can be seen getting cleaned on coral reef cleaning stations, which are shared by many different fish species, and feed around reef channels and passes on strong incoming currents, when plankton is being pushed up reefs and into channel mouths.

Shown here are aerial photos taken by helicopter of feeding mantas around channels and reef passes in Palau. While German Channel and Devilfish City are the best known manta sites in Palau, almost every channel and reef pass has cleaning stations and manta feeding sites where mantas show up, depending on the tides and wind direction. Ngardmau and Ngarchelong state have the largest concentrations of manta rays in Palau. We now believe these reef mantas never leave the Palau area, but follow the plankton around the reefs. The same mantas have been photographed all around Palau, and in general stay around the western reefs from October to May when the winds are from the east, moving to the eastern reefs when the trade winds change.