Deep snow can sometimes appear blue because the extra layers of snow create a filter for light.
100 Mind-Blowing Filter Facts
Kleenex tissues were originally intended for gas masks. When there was a cotton shortage during World War I, Kimberly-Clark developed a thin, flat cotton substitute that the army tried to use as a filter in gas masks. The war ended before scientists perfected the material, so the company redeveloped it to be smoother and softer and then marketed Kleenex as facial tissue instead.
Kleenex tissues were supposed to be for gas masks. During a cotton shortage in World War I, Kimberly-Clark devised a thin, flat cotton substitute to use as a filter for army gas masks. However, the war ended before scientists could perfect the material. In turn, the company constructed a thinner and softer material that eventually became Kleenex tissues.
Flamingos eat with their heads turned upside down. Flamingos are unable to eat normally due to the structure of its mouth. Their bills are made to filter food from the mud and water. They feed by coming through the mud with their feet and catching their prey in their beaks.
WHALES ARE DIVIDED INTO TWO MAIN GROUPS. There are two types of whales: the baleen whales and the toothed whales. Baleen whales, including humpbacks and blue whales, have fibrous ‘baleen’ plates in their mouths instead of teeth, which help them filter out and consume huge quantities of zooplankton: small prey including krill, fish or crustaceans called copepods. Whereas toothed whales, such as orcas, beluga and sperm whales, have teeth which enable them to feed on larger prey such as fish and squid. All dolphin families, including porpoises, are also classified as whales, as they are more related to their toothed counterparts.