Honey Possums or Noolbengers (Tarsipes rostratus) are tiny, five to ten gram mouse-sized marsupials that only occur in south-western Australia. Honey Possums only eat the nectar and pollen from the flowers of woody shrubs growing on the heathlands, known as Kwongan, and are the only entirely nectar-feeding mammals that are not bats. They use their pointed snouts and long sticky tongues to extract the nectar they need. Honey Possums are keystone species in the sandy coastal plains of south-western Australia and are thought to be important pollinators of woody Banksia and Adenanthos shrubs, as well as for other flowering plants. They carry pollen on their heads and seem to be more effective pollinators than the Honeyeaters and other birds that feed from the same flowers. The Honey Possum in this video is a male with very obvious testes. Honey Possum testes are proportionally the largest of any mammal, about 4.6 percent of body weight, and their sperm is the longest known.