Gee Whiz

Sea Otters: Unique Hunters

Sea otters are marine mammals that are part of the weasel family and well-known for their cute face, furry plush coat, and efficient hunting ability. Climate change may have harmed many species worldwide, but no species has fought back like the otter. These mammals are ultimate climate change reducers.

Yes, that’s right. Sea otters reduce carbon dioxide in the atmosphere by eating sea urchins. Sea urchins eat kelp and kelp help reduce carbon dioxide from the atmosphere by it through photosynthesis. An average adult male sea otter can eat up to a staggering fifty sea urchins a day! For a one hundred and fifty pound person, that is the same as eating one hundred and sixty quarter pound hamburgers. That is a lot of carbon dioxide absorbed from the atmosphere. So, while we may be adding to the problem of climate change, sea otters are helping to reduce climate change. How do they achieve this? What are their feeding behaviors?

During a sunny, summer day a female sea otter rests on an isolated island of rocks in the middle of the ocean. It is feeding time and the otter is becoming more hungry and impatient, so it takes a leaping dive into the water in hopes of finding a potential meal. Otters spend a lot of time diving for food because it is essential for their survival. They can dive to hundreds of feet for several minutes in search for food. However, they prefer to stay in shallower waters and make quicker dives instead.  They will swim for hours searching for as much food they can find, especially their favorite, sea urchins.

Once under water the otter uses its whiskers and nose to find food by detecting vibrations under the water. Suddenly, she spots her favorite prey, a sea urchin attached to a rock beside a kelp forest. The otter becomes excited and quickly snatches any rock it can find and uses it to detach the urchin from the rock. A few quick powerful hits and the sea urchin is knocked off the rock. She does not want to risk losing her prize, so she uses the loose fold of skin under her armpit like a shopping bag to tuck the urchin away.

After catching its prey the otter swims like a torpedo up to the water’s surface. She attempts to pry open the sea urchin with her forelegs and paws but nothing works. She is frustrated and disappointed but is not ready to give up, so it goes on the search for a rock to break it open. The otter takes the rock and repeatedly smashes its prey vigorously. The otter succeeded in cracking open the urchin and now all that hard work is rewarded with a meal. The otter lies on its back and keeps itself afloat. It places the urchin on its stomach and uses its paws to hold it and with its sharp teeth the otter rips easily into the sea urchins insides.

Otters are one of the few animals who use tools to open up their food. Like having their favorite toy, some otters even save their favorite rock tool in their armpit for further use.  They use a variety of methods to break their prey open with rocks. Some otters will place a rock on their chest and smash their prey on it until it breaks open. Others will place their prey on their chest and use the rock as a hammer. Some otters will use several quick strikes or a few strong hits. For large shellfish this tool is useful for knocking prey off rocks, but for small shellfish their strong arms are powerful enough to pry their prey off.  Food that is underground, such as clams, can be found by digging. Otters dig with their forepaws, like dogs, to get their prey and sometimes they will use rocks to dig.

Individual otters have distinct food preferences. Some may eat only sea urchins, while others might eat only crabs and abalone. Some prey may be hard to find because they hide from predators like otters, but they are intelligent hunters and can easily find them. Like people they always clean up after themselves when feasting on a meal. They will roll over in the water to remove any scraps of food off their chest.

Once the otter grows up to become an adult female otter it is an appropriate time in her life to have babies. Now it is her mission and obligation to teach them everything she knows about hunting for food so they can start hunting for sea urchins by themselves. When the otter is two and a half months old it dives with its mother in search for food. Once food is caught the mother shows her baby how to use rocks to break open prey. Otters are intelligent mammals, so it does not take long for them to learn these techniques.

To maintain a normal body temperature, adult otters eat about twenty-five percent of their body weight per day and eat every three hours. Otters eat over a hundred and sixty types of different food. Among them include clams, snails, abalone, crabs, starfish, mussels, scallops, squid, chitons, small octopuses, sea urchins, prawns, sea cucumbers, limpets, marine worms, several types of fish, and a variety of other things. Sea otters are diurnal, which means they hunt mainly during the day.  They are in search for food several hours in the morning, typically starting just before sunrise.  They are on a food hunt again in the afternoon, which usually lasts for several hours until sunset.  They groom each other and rest after each of those feedings. Then they are on a food search again around midnight. Now, that is a lot of grub!

Sea otters are efficient hunters because they have such unique feeding habits and behaviors. It’s their intelligence and will that makes them unique hunters. Their unique hunting techniques are beneficial for hunting sea urchins, which is why they are able to get so many of them. This makes them excellent climate change reducers.

By: Amanda Boudreau

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