image: A seven day old white sea bass larva lives in seawater. They were photographed using a dissecting microscope. You will note two bright objects in the left side of the fish head, just behind the eye and slightly toward the center. These are a pair of otoliths. They are made to stand out by using cross-polarization: one polarizing filter is above the fish, another below it, but oriented 90 degrees with respect to the upper filter so that the field is largely dark. The otoliths are birefringent (i.e change the polarization of the light), making them appear bright on the dark background. We use this method to see the otoliths in order to extract them to place on the SEM stubs for imaging. The larger of the otoliths is only ~40-50 microns wide. This image relates to an article that appeared in the June 26, 2009, issue of Science, published by AAAS. The study, by Dr. David Checkley of the Scripps Institute of Oceanography, University of California, San Diego in San Diego, Calif., and colleagues was titled, "Elevated CO2 Enhances Otolith Growth in Young Fish". view more
Credit: Image courtesy of David Checkley