Otter females are called bitches or sows, and their offspring are called pups. The collective nouns for otters are bevy, family, lodge, romp (being descriptive of their often playful nature) or, when in water, raft. The feces of otters are typically identified by their distinctive aroma, the smell of which has been described as ranging from freshly mown hay to putrefied fish; these are known as spraints. The gestation period in otters is about 60 to 86 days. The newborn pup is cared for by the bitch, dog and older offspring. Bitch otters reach sexual maturity at approximately two years of
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