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Sea Otter Awareness Week is celebrated annually from September 21 to September 27 to highlight not only why the keystone marine mammal needs to continue to be protected, but also the threats the endangered species continues to face. If sea otters were to go extinct in regions where they are present, the health of local kelp forests would likely decline significantly. This is because sea otters help control sea urchin populations, which can otherwise decimate kelp beds. Fortunately, sea otters target the sea urchins and are proving to be an important key in the recovery of kelp in the ocean.
It is not only sea urchins that sea otters feast on. Thanks to the ingenious side of sea otters, these marine mammals are capable of eating prey that theoretically should be far too tough to consume. Because of this, the ocean is a virtual smorgasbord to sea otters, limited only by how creative the critters can be when on the hunt for a meal.
Sea Otters and Their Tools
It was only discovered several decades ago that sea otters use tools.
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The use of tools by animals is something that has been observed for centuries. However, primates and birds have tended to be the animals that receive the most attention for their cleverness when it comes to using an object to reach an end goal.
Those animals that live in the sea, such as dolphins and octopuses, were not observed until more recent decades using tools. This has a lot to do with technology needing to be advanced enough to discover what marine animals do beneath the waves.
It is believed that sea otters have used tools for millions of years. Yet they were not discovered doing so until several decades ago. It was not until scientists did multi-day observations of sea otters in 1964 in California that they found the largest members of the weasel family were very intelligent indeed. The sea otters lay on their backs and used rocks to pry open shelled creatures they otherwise would not have access to. It is because of this that in areas where sea otters have a varied diet, populations have not decreased as dramatically as they have where prey is not as diverse, despite climate change and loss of habitat in the last handful of decades.
How Sea Otters Use Rocks to Open Food Sources
Sea otters use rocks as tools to crack open a variety of food sources.
©Alaskan Wildlife/Shutterstock.com
Sea otters use their tools to open prey with hard shells. If the marine mammals lacked the intelligence to use rocks and other items to break open their food, their diet would be substantially different.
What is interesting to note is that while all sea otters have the capability to use tools to crack open hard-shelled prey, the habitat they live in determines whether tools are a necessary part of daily life. In areas with fish and soft-shelled creatures to feast on, such as Alaska, tools are not always necessary for eating. However, in places like California, where there are hard-shelled creatures to feast on, sea otters use tools far more frequently.
When sea otters use tools, it is not just a rock they pick up and then discard when a shell has been opened. Instead, sea otters have a favorite rock they hold onto, which serves as their go-to tool for most of their eating needs.
Sea Otters Have Favorite Rocks
Sea otters have a favorite rock they will carry with them for weeks to months at a time.
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Just like people have their favorite tools when it comes to building, sea otters have their favorite rocks. These rocks are so important to sea otters that they will hold onto them for weeks or even years in some cases. The rocks that sea otters choose are specifically picked for their weight and size compared to the particular sea otter. Rocks cannot be too heavy to manipulate, nor can they be too smooth to crack open the shells of marine creatures.
To keep favorite rocks safe, sea otters will place them in their “pockets.” These pockets are not like the pockets marsupials have. Instead, the pockets are skin flaps that sea otters have under their forearms. These flaps are secure enough that sea otters can travel with their favorite rock in them, as well as extra food they want to save for later.
The favorite rock will be held onto until it is either unfortunately lost or broken, or until the sea otter finds another rock it deems to be a better tool. A new rock would have to be remarkably better than the last; however, given that sea otters have what appears to be an attachment to their rocks. Why the attachment is so great is still unknown. However, given the amount of time the favorite rock is kept and the care that goes into keeping it safe, a bond is clearly there. But, just because these special rocks are the tools that sea otters use most often, it is not the only type of rock the marine animals will turn to when trying to open a shelled sea creature.
Other Tools Sea Otters Use
Sea otters may use more than their favorite rock to gain access to prey.
©Matt Knoth/Shutterstock.com
The tool that sea otters will most often turn to, to open their hard-shelled meals, is their favorite portable rock. However, these rocks are not the only thing that sea otters use to gain access to prey. Sea otters are intelligent enough to use other tools if their favorite rock alone is not doing the job.
Sea otters have been observed using a variety of tools outside of their special rocks to make a meal out of a successful hunting trip consisting of creatures with hard shells. Some of the other tools otters have demonstrated using include:
- Larger rocks are used as “anvils” to break open crabs, clams, and mussels
- Sides of boats to bang shelled creatures against in an attempt to open them
- Glass bottles to pry open difficult shells
- Crab claw to open the shell of a crab
Given how well tools work for sea otters, it would make sense if all sea otters used them consistently. But, depending on the diet they eat and the location they live, sea otters may use tools more or less often. The sex of the sea otter even plays into how often tools are used, impacting the oral health of one half of the species more than the other.
Female Sea Otters Are More Likely to Use Tools Than Males
Female sea otters are more likely to use tools when hunting, giving them more options for food and healthier teeth.
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Despite being smaller in stature, female sea otters have found a way to eat a more varied diet than their male counterparts. This is because female sea otters are more apt to use tools than males are. According to a 2024 study in Science, if female otters were only able to eat foods that their teeth and jaws could break through, their diet would be significantly decreased. Female otters, lead author of the study and biologist at the University of Texas and the University of Washington, Chris Law, says, would have to eat smaller prey that is softer than that found in shells.
“They typically wouldn’t be able to break into harder prey,” Law explains to NPR. “But they use tools more than males, so they’re able to gain access to these novel sources of food items.”
Therefore, female sea otters can eat prey that is not only larger but also more nutritious. Additionally, the study states that sea otters use tools to protect their teeth. Therefore, the more often sea otters use tools available to them, the less likely they are to break a tooth. Consequently, given that female sea otters use tools more often, scientists believe they also have healthier and stronger teeth. This is important because if sea otters do not have healthy teeth in their mouths, they are not able to eat. Consequently, those sea otters will also not survive.
What Nearly Going Extinct Meant For Sea Otter Generational Knowledge
While sea otters teach their young how to use rock tools, the younger otters have rudimentary tool skills already predisposed.
©MODpix/Shutterstock.com
Sea otters were nearly hunted to extinction in the 18th and 19th centuries. From the San Francisco Bay alone, as many as 10,000 sea otters were killed for their pelts. Where there were once 300,000 in the Pacific Northwest, there are an estimated 150,000 left worldwide, and just 3,000 in California.
As the adult sea otters were removed en masse from the bay and other regions they inhabited, there was a loss of generational knowledge of not only what to hunt but also how to use different rocks as tools. However, thanks to sea otters using rocks as tools for millions of years, rudimentary tool skills appear to be predisposed. Because of this, all was not lost for the sea otters who survived the time of the pelt trade.
According to a 2017 study published in Biology Letters, while mother otters do teach their young how to use rocks as tools and even go as far as to find rocks that are the right size and weight for baby otters to practice with, otters already intrinsically know how to use rocks as tools. This, in addition to the laws protecting sea otters from being hunted, may have helped the population rebound faster than if the hunting and tool-using techniques had to be passed down from one generation to the next.
“Orphaned otter pups raised in captivity exhibit rudimentary pounding behavior without training or previous experience, and wild pups develop tool-use behavior before weaning regardless of their mother’s diet type,” the study says.
Sea otters are incredibly intelligent marine mammals that have learned to use rocks and other objects in and around the ocean to forage for a varied diet. Without sea otters as apex predators of the “marine nearshore environment,” helping to keep sea urchins at bay, kelp beds and kelp forests that the sea otters and other marine life live in would disappear.
Climate change and an increase in sea urchins have caused the kelp forests to decline significantly over the last few decades. The hope is that sea otters will be able to regulate the urchins with their hunting skills. Although the numerous sea urchins are not as nutrient-dense as sea otters would prefer, sea otters continue to target these spiny sea creatures, thereby benefiting the health of the ocean and its numerous habitats.
The post This Sea Otter Awareness Week, Learn More About These Clever Animals appeared first on A-Z Animals.
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