These highly magnified images of marine organisms from Puget Sound and the Pacific Ocean were taken with a scanning electron microscope (SEM) at National Oceanic and Atmospheric Administration (NOAA), Northwest Fisheries Science Center (NWFSC) in Seattle. Occasionally, the samples examined as part of research projects have an incredible beauty, or sometimes by sheer luck, the timing is just right to show a unique moment in the life of a marine organism.
Fisheries biologist Carla Stehr and other NOAA scientists have used the SEM to conduct research at the NWFSC for over 30 years. Images from the SEM have helped the NWFSC advance scientific knowledge about aquatic organisms (e.g. development of fish), the human influence on marine organisms (e.g. effects of man-made contaminants) and the influence of marine organisms on humans (e.g. toxic diatoms responsible for harmful algal blooms).
Scanning electron microscopes use electrons to provide information about the surface structure of a sample. The wavelength of electrons is thousands of times shorter than light, so SEMs are able to magnify thousands of times greater than a light microscope. The best light microscopes can magnify up to 2,000 times, while many SEMs can magnify images up to 300,000 times or more. The magnifications used for the biological samples examined at the NWFSC generally range from 30 to 80,000 times. SEM images also have a greater depth of field compared to light microscopes. Moreover, because the electron wavelengths are much shorter than visible light, SEM images do not have any color. Although artificial color can be added, the original black and white images are shown here to highlight the incredible structures present on aquatic organisms. For more detailed information about the microscope and sample preparation techniques, click here.
An AMRAY 1000 SEM was used from 1975 to 2003. It used analog technology and 4 × 5 inch Polaroid film to record the images. The SEM was replaced in 2003 with a JEOL 6360LV SEM, which records images digitally.