It seems likely, although the fossil evidence is inadequate to prove it, that Pteronura populated South America and Lutrogale Asia just before the adaptable and successful Lutra otters came along, and that both genera are remnant populations which may well eventually die out. The social behavior of otters ranges from solitary to family living. Lutra species, such as the Eurasian otter, are basically solitary. Although a male and female may pair for several months during the breeding season, there is no strong pair bond between them and the male is dominant during their temporary associations. Play serves to reinforce social bonds, so important to social otters, but also helps young otters perfect their hunting and fighting techniques.
Otters are very vocal, with a large repertoire of calls.
Different vocalizations readily distinguish Lutra from Lutrogale and both of these from Aonyx. Differences in vocalization are to be found mainly in these contact , summons and greeting calls, but similarities, especially in threat and alarm calls, remain. Scent marking is a common feature of otter behavior. Only the exclusively marine Sea otter lacks the paired scent glands at the base of the tail which give otters their heavy, musky smell. Scent marking delineates territorial boundaries and communicates information concerning identity, sex, sexual state, receptivity and time elapsed between scenting visits.