Marine Mammal Protection Act Indian manatee, sea otter, polar bear, and Pacific walrus. Species not present in U.S. waters include the West African and Amazonian manatee, dugong, Atlantic walrus, and marine otter. In efforts to conserve and manage marine mammal species, the Service has appointed field staff dedicated to working with partners to conduct population censuses, assess population health, develop and implement conservation plans, promulgate regulations, and create cooperative relationships internationally. Various Marine Mammal Management offices are located on either coast. The Service's Marine Mammal Management office in Anchorage, Alaska is responsible for the management and conservation of polar bears, Pacific walruses, and northern
Mammal destruction]], though there are efforts to combat this. [[File:Mammal species pie chart.svg|thumb|upright=1.35|The orders [[Rodent]]ia (blue), [[Chiroptera]] (red) and [[Soricomorpha]] (yellow) together make up over 70% of mammal species. Mammal classification has been through several iterations since [[Carl Linnaeus]] initially defined the class. No classification system is universally accepted; McKenna & Bell (1997) and Wilson & Reader (2005) provide useful recent compendiums. [[George Gaylord Simpson]]'s "Principles of Classification and a Classification of Mammals" (AMNH "Bulletin" v. 85, 1945) provides [[systematics]] of mammal origins and relationships that were universally taught until the end of the 20th century. Since Simpson's classification, the [[fossil