Otters are aquatic mammals that are carnivores. They thrive in diverse aquatic habitats across nearly every continent, excluding Australia and Antarctica. Belonging to the Mustelidae family, which includes weasels and badgers, otters have a high metabolism that necessitates frequent feeding.
What Otters Eat
Otters primarily eat aquatic organisms. Fish forms a substantial part of their diet, with specific types varying by species. North American river otters, for instance, commonly consume slow-moving fish like perch, suckers, and catfish, typically 4 to 6 inches long. Their diet also includes crustaceans such as crayfish and crabs, and amphibians like frogs and salamanders.
Different otter species vary their food preferences based on habitat. Sea otters, residing in coastal marine environments, primarily prey on marine invertebrates. Their diet includes sea urchins, mollusks like clams, mussels, and abalone, and crustaceans such as crabs. Northern sea otters may also consume fish.
Some species, like the Asian small-clawed otter, may occasionally prey on small mammals or ground-nesting birds, adapting to local food availability. Otters possess strong jaws and blunt teeth for crushing the shells of their prey. They must consume a significant amount of food daily, with sea otters eating approximately 25% to 30% of their body weight and river otters consuming 15% to 20%.
How Otters Hunt and Forage
Otters employ various hunting strategies, leveraging agility and senses. Their streamlined bodies, webbed feet, and powerful tails enable swift movement through water, allowing effective pursuit of fish. Otters often hunt individually or in pairs, though some species may forage in groups.
Their senses play a role in locating prey, particularly in murky aquatic environments. Otters possess highly sensitive whiskers, or vibrissae, which detect subtle changes in water currents and vibrations from prey movement. These whiskers are crucial for identifying prey size and shape. While vision is also used in clearer waters, their tactile senses are particularly developed for underwater foraging.
Some otter species use tools to access food. Sea otters are known for using rocks to break open hard-shelled prey like mussels, clams, and sea urchins. They often float on their backs, placing a rock on their chest as an anvil to smash their catch. This behavior helps them access difficult prey and can reduce tooth damage. Sea otters can store collected food and sometimes a favorite rock in loose skin pouches under their forearms.