Sea otters eat a wide variety of prey, including marine invertebrates such as echinoderms (sea stars and sea urchins), crustaceans (e.g., crabs), cephalopods (e.g., squid), bivalves (clams, mussels, abalone), gastropods (snails), and chitons.
They obtain their food by diving - foraging dives can last up to 5 minutes. They find and grasp their food using their agile front paws, and can also sense prey using their whiskers.
Sea otters are one of the only mammals known to use tools to obtain and eat their prey. They can use a rock to dislodge mollusks and urchins from the rocks where they are attached. Once at the surface, they often eat by placing the food on their stomachs, and then placing a rock on their stomachs and then smashing the prey on the rock to open it and get at the flesh inside.
Sea otters have loose skin, and baggy "pockets" underneath their forelimbs. They can store extra food, and rocks used as tools, in these pockets.
Sea otters have a high metabolic rate (that is, they use a high amount of energy) that is 2-3 times that of other mammals their size. Sea otters eat about 20-30% of their body weight each day. Otters weigh from 35-90 pounds (males weigh more than females). So, a 50-pound otter would need to eat about 10-15 pounds of food per day.
The food sea otters eat can impact the entire ecosystem in which they live. Sea otters have been found to play a pivotal role in the habitat and marine life that inhabit a kelp forest. In a kelp forest, sea urchins can graze on the kelp and eat their holdfasts, resulting in deforesting the kelp from an area. But if sea otters are abundant, they eat sea urchins and keep the urchin population in check, which allows kelp to flourish. This, in turn, provides shelter for sea otter pups and a variety of other marine life, including fish. This allows other marine, and even terrestrial animals, to have abundant amounts of prey.
Sources and Further Information
- California Sea Otter. Friends of the Elephant Seal. Accessed September 29, 2012.
- Laustsen, Paul. 2008. Alaska's Sea-Otter Decline Affects Health of Kelp Forests and Diet of Eagles. USGS. Accessed September 28, 2012.
- Monterey Bay Aquarium. 2011. Facts About Sea Otters. Accessed September 27, 2012.
- Sea Otters. Vancouver Aquarium. Accessed September 29, 2012.
- The Marine Mammal Center. Animal Classification: Sea Otter. Accessed September 26, 2012.