Hiding in plain sight

Single-celled organisms like this tintinnid are critical links in the ocean’s food web. Though ever-present in the world’s oceans, their microscopic sizes make them hard to sample and therefore hard to study. Found in Antarctic waters, this organism has a transparent vase-like shell for protection. Tintinnids consume a variety of cells and non-living particulate organic material, and are 0.02 to 0.1 meter (0.04 to 0.79 inch) long. (Photo by Dawn Moran, Woods Hole Oceanographic Institution)