Van Dorn bottles, named after Dr. William Van Dorn of Scripps Institute of Oceanography, include the well-regarded Alpha™ and Beta™ bottles. These samplers obtain composite
samples from several depths or pool samples from one depth and thus can be used for both horizontal and vertical sampling. Horizontal bottles are often used for sampling at the thermocline, at other stratification levels, or just above the bottom. Because they collect whole water samples, all size classes of phytoplankton are obtained.