Nautilus (genus)

Nautilus is a marine cephalopod genus in the mollusk family Nautilidae. Species in this genus differ significantly, morphologically, from the two nautilus species in the adjacent sister-taxon Allonautilus. The oldest fossils of the genus are known from the Late Eocene Hoko River Formation, in Washington State and from Late-Eocene to Early Oligocene sediments in Kazakhstan. The oldest fossils of the modern species Nautilus pompilius are from Early Pleistocene sediments off the coast of Luzon in the Philippines. The commonly used term 'nautilus' usually refers to any of the surviving members of Nautilidae, and more specifically to the Nautilus pompilius species. The entire family of Nautilidae, including all species in the genera Nautilus and Allonautilus, is listed on Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Various authors claim that the genus consists of between four and seven extant species; this remains the subject of debate. Nautiloids are typically found in shallow ocean waters in tropical seas, mainly within the Indo-Pacific, from the Coral Triangle and Strait of Malacca to the open water South Pacific islands. The genus Nautilus includes several species represented in the fossil record; however, these have also been contentious in their placement, and some are only provisionally accepted.