The otter's 'whine' and 'squeal' that is commonly heard during courtship has been found to consist of graded signals that vary over a continuum. This degree of complexity and richness of communication patters is believed to have evolved as a result of complex social relationships. Feeding The sea otter has been described as a resourceful, voracious and gregarious, generalist predator. Recent studies have revealed that otters do not forage cooperatively, and rarely exhibit other types of coordinated group movement. Small feeding groups are common, and although large aggregations have been observed, they are rare.
Individuals dive in search of prey and return to the surface to breathe and consume their catch.
Otters have been observed to forage at night as well as during the day, and there is a great deal of individual variation in diet and foraging patterns. Diets are known to primarily consist of fish and marine invertebrates, including various species of mussels, tunicates, sea stars, bivalves, crabs, abalone and octopus. Occasionally, otters have been observed to feed on some kelp species, but algae is not believed to be a main part of their regular diet. Dive duration has been observed to vary with prey type, with mean dive lengths of about 74s, and longer dives approaching 246s. E. lutris demonstrates significant selectivity and intelligence when foraging and consuming its prey.