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 years ago. This tiny primate weighed 20–30 grams (0.7–1.1 ounce) and could fit within a human palm. Living mammal species can be identified by the presence of [[sweat gland]]s, including [[Mammary gland|those that are specialized to produce milk]] to nourish their young. In classifying fossils, however, other features must be used, since soft tissue glands and many other features are not visible in fossils. Many traits shared by all living mammals appeared among the earliest members of the group: For the most part, these characteristics were not present in the Triassic ancestors of the mammals. Nearly all mammaliaforms possess an