The North American river otter (Lontra canadensis) is a semiaquatic mustelid -- a member of the weasel family -- native to a large swath of the United States and Canada, as well as northwestern Mexico. Social, playful and charismatic, river otters are also formidable hunters at or near the top of the freshwater and coastal food chain wherever they’re found. They feed on a very wide range of prey, primarily fish and crustaceans.
Fish as Prey
Fish represent a foundational component of the river otter's diet. Otters generally are opportunistic fish-eaters, most often nabbing slower-swimming species -- especially bottom dwellers -- and impaired individuals. Commonly eaten fish include perch, suckers, sculpin and catfish.
River otters also heavily favor crayfish in many areas. Other typical freshwater prey includes frogs, turtles, waterfowl and small mammals. Otters utilizing coastal marine habitats often snatch crabs and molluscs. In the Southeast, otters occasionally eat young alligators -- normally hatchlings, although a photographer in Florida captured an ambitious otter dispatching a 1.5-meter (5-foot) juvenile gator.
Comparison with Other Otters
The North American river otter essentially eats any animal it can catch and overpower, similar to the dozen other species of freshwater otter found elsewhere in the world. The 2-meter-long (7-foot-long) giant otter of South America, biggest of all, sometimes tackles even caimans and anacondas, particularly when hunting in groups.