Sea Urchin - Planktonic Origins Barely visible to the naked eye, sea urchin larvae grow and transform into bottom-dwelling urchins.
Crab larva (Photo : Fabien Lombard)
Average chlorophyll concentration in the surface ocean (from mi-September 1997 to August 2007) from the ocean color sensor SeaWiFS (NASA). Subtropical gyres, in the center of the oceanic basins, are characterized by very low concentrations of chlorophyll a (dark blue) - Source : NASA's Earth Observatory (http:/earthobservatory.nasa.gov)
