Benthic animals are those which live within the substratum or at the substratum/water interface, and they feed on particulate matter at these locations or from the water column just above the interface. Some animals use secreted nets to intercept particles passing over them in currents of water. Freshwater animals manufacture silk nets from salivary secretion, and marine animals produce nets of mucus. Nymphs of the mayfly Ametropus neavei bury themselves in sandy substrata in rivers and feed by means of the forelegs which bear setae, and which are held into the current. The ciliated Protozoa have tracts of cilia which bring particles to the mouth for ingestion, and lophophorates have “a crown of ciliated tentacles” which perform the same function. Benthic suspension feeders are mainly sedentary and, unlike some deposit feeders and zooplankton, do move readily in search of high-quality food.