The marine otter (Lontra felina) is a rare and relatively unknown South American mammal of the weasel family (Mustelidae). The scientific name means "otter cat", and in Spanish, the marine otter is also often referred to as : "marine cat". The marine otter (while spending much of its time out of the water) only lives in saltwater, coastal environments and rarely ventures into freshwater or estuarine habitats. This saltwater exclusivity is unlike most other otter species, except for the almost fully aquatic sea otter (Enhydra lutris) of the North Pacific. Description The marine otter is one of the smallest otters and the smallest marine mammal, measuring from the nose to the tip of the tail and weighs . The tail measures . Its fur is coarse, with guard hairs measuring up to in length covering dense, insulating underfur. The marine otter is dark brown above and on the sides, and fawn on the throat and underside. The marine otter has webbed paws and strong claws. The ventral side (underside) of the paws are partially covered in fur. It has 36 teeth and a dental formula of . The teeth are developed for slicing instead of crushing. The marine otter does not display sexual dimorphism. Distribution and habitat Marine otters are found in littoral areas of southwestern South America, close to shore and in the intertidal areas of northern Peru (from the port of Chimbote), along the entire coast of Chile, and the extreme southern reaches of Argentina. Occasional vagrant sightings still occur as far afield as the Falkland Islands. The marine otter mainly inhabits rocky shorelines with abundant seaweed and kelp, and infrequently visits estuaries and freshwater rivers. It appears to select habitats with surprisingly high exposure to strong swells and winds, unlike many other otters, which prefer calmer waters. Caves and crevices in the rocky shorelines may provide them with the cover they need, and often a holt will have no land access at high tide. Marine otters avoid sandy beaches. Behavior Rocky intertidal zones with natural crevices are ideal for marine otter dens and feeding areas. Because most of their time is spent hidden in caves, their behavior is difficult to observe. Marine otters actively avoid humans. In response to human activity, they will spend less time on coasts and stray from their dens during the day to fissures inaccessible to humans. Though generally avoidant of humans, their