Sea otters are recognized for his or her exceptionally thick, two-layered coats, which may have over one million hairs per sq. inch. Since they lack blubber, they depend on this superb fur—the densest within the animal kingdom—to remain heat.
Sea otters could be a highly effective ally in confronting local weather change, in response to the Monterey Bay Aquarium in California. In locations the place they’re thriving, they’ll keep and restore kelp forests and coastal wetlands, strengthening our pure defenses towards the worst impacts of a warming world.
That’s one of many causes that we rejoice them yearly over the past full week of September. In 2025, Sea Otter Consciousness Week runs from September 21 to 27. Occasions that spotlight the significance of sea otters and their ecosystems typically embody instructional actions and shows from conservation organizations; alternatives to study from volunteers about sea otters and the way to assist defend them; and on-line occasions, equivalent to digital visits to coastal places and social media campaigns.
Sea otters eat 25% of their physique weight in meals each day. They’re predators, whose diets embody clams, crabs, mussels and sea urchins, which they’re recognized to crack open with a device (equivalent to a rock) and eat whereas floating within the water. Now, sea otters are exhibiting us that the lack of a predator in a single ecosystem can ship shock waves into one other—in ways in which we haven’t understood earlier than. And with local weather extremes like marine heatwaves on the rise, understanding how numerous ecosystem adjustments can reverberate into different ecologies is central to growing efficient conservation methods.
Sea otters eat quite a lot of meals, together with clams, crabs, mussels, octopuses, sea stars and sea urchins. They’re opportunistic hunters, typically specializing in numerous prey relying on native availability and their realized looking expertise. Sea otters are recognized to make use of rocks as instruments to crack open laborious shells.
On the flip aspect, sea otters are additionally prey for different animals. Unexpectedly, coastal wolves residing in Alaska that eat sea otters have a lot larger concentrations of mercury than these consuming different prey, equivalent to deer and moose.
In honor of Sea Otter Consciousness Week, then, let’s check out these furry, versatile and fetching marine mammals.
Sea otters reveal the connectedness of ecosystems
Pisaster is a genus of sea stars (also called starfish). Essentially the most well-known species of Pisaster is the ochre sea star (Pisaster ochraceus). In 2013, a sea-star losing syndrome decimated populations of Pisaster alongside the West Coast of North America and alongside the Monterey Peninsula in California. The brownish-red, orange, purple and yellow stars have a hearty urge for food for mussels in rocky, intertidal areas. With out the voracious sea stars lurking round, mussel populations exploded, increasing in cowl from about 5% to greater than 18% inside three years. Within the wake of the sea-star die-off, mussels grew to become a significant prey surplus for sea otters, revealing a stunning hyperlink between adjoining intertidal zones and kelp-forest ecosystems. The brand new analysis into the phenomenon reveals how the lack of a keystone predator (Pisaster) in a single ecosystem can change one other predator (sea otters) in different ecosystems.
Discovered on shores from Alaska to California, ochre sea stars sport vibrant colours and 5, stout arms lined in small spines. They primarily prey on mussels, serving to to keep up biodiversity in tide swimming pools by stopping the mussels from dominating ecosystems.
Monterey Bay Aquarium researchers have been observing sea-otter foraging conduct for many years. Sea otters devour their prey on the floor, which is vital to recording what they eat and the place they seek for meals. Following the lack of Pisaster, sea otters greater than doubled their mussel consumption, rising from lower than 7% to just about 18% of their general weight-reduction plan. The native variety of sea otters additionally elevated from a decade (2000–2012) common of 373 to 535 between 2014 and 2024, and the prey surplus supported the elevated numbers.
Will increase in mussel consumption by sea otters had been documented by the Multi-Company Rocky Intertidal Community (MARINe), a consortium of organizations that conduct long-term ecosystem monitoring. The MARINe group sampled 4 places over a number of many years in intertidal areas alongside the Monterey Peninsula. For every survey, they recorded data on the variety of sea stars, the duvet of mussels and the way far the mussel beds prolonged from the higher tide swimming pools towards the water. This long-term monitoring knowledge was pivotal to cinching the correlation between the decline in sea stars and the rise in mussels.
The 2013 sea-star losing occasion was abrupt; by late 2013, the native inhabitants of stars had practically collapsed. Predators like sea stars and sea otters are important to sustaining resilient ecosystems. When these predators are eliminated, every thing crumbles, mentioned the researchers, who coined the time period keystone interdependence, the place the lack of a predator in a single ecosystem doesn’t simply have an effect on that specific ecosystem, it additionally extends to adjoining ecosystems, even benefiting different predators.
In a stunning coastal ecosystem ripple impact, it was discovered that the collapse of 1 marine predator can profit one other. The mass die-off of ochre sea stars created a mussel increase—providing sea otters an sudden prey buffet. After sea stars get better, sea otters could should shift their diets as soon as once more.
Though sea otters thrived in response to the elevated availability of mussels, researchers warning this may solely be momentary. With fewer sea stars, extra mussels survived to succeed in maturity, and their common dimension grew bigger. Now that mussels are reaching sizes which can be too massive for sea stars to devour, a return to the earlier stability could also be gradual—even after Pisaster recovers. Nonetheless, the scientists hypothesize that sea otters may need to shift their diets as soon as once more, after they deplete the overabundance of huge mussels and after Pisaster finally recovers.
The examine additionally highlights how local weather change compounds the results of ecosystem shifts. Shortly earlier than the mussel inhabitants improve, the biggest marine heatwave on file occurred within the northeast Pacific Ocean, from 2014 to 2016. Within the sweltering sea temperatures, kelp-eating sea urchin numbers exploded, kelp forests declined and sea otters switched their diets towards consuming extra sea urchins. Later, the ocean otters swiveled once more; this time, towards mussels as this prey surplus grew to become obtainable.
The scientists state, of their article printed within the journal Science Advances in April 2025, that conservation efforts hardly ever take into account how adjoining ecosystems are linked. Their findings display that predators are necessary for enabling ecological resilience; and that once they decline in a single ecosystem, the results could manifest in one other.
Sea otters eat each purple and crimson sea urchins, however they primarily goal purple sea urchins attributable to their bigger dimension and dietary worth. Sea otters are a keystone species in kelp-forest ecosystems, as their consumption of sea urchins prevents them from overconsuming the kelp that’s important for marine life.
Coastal wolves expose the mercury in sea otters
In late 2020, a feminine coastal wolf collared for a examine on predation patterns unexpectedly died in southeastern Alaska. The wolf, No. 202006, was solely 4 years outdated.
After researchers on the Alaska Division of Fish and Recreation performed a necropsy and completely different analyses of the wolf’s tissues, it was found that the reason for her loss of life was unprecedented concentrations of mercury in her kidneys, liver and different tissues.
Mercury is a naturally occurring component that people launch from the Earth’s crust by way of coal combustion and small-scale gold mining. It’s a steel that may be liquid at room temperature or a vapor. When mercury will get into the ambiance in its elemental type, it could possibly journey for very lengthy distances.
Coastal wolves are a genetically distinct subspecies of grey wolf discovered alongside the coasts of Alaska and Canada. Distinctive for his or her semiaquatic way of life, coastal wolves swim between islands and forage for marine-based meals like salmon, shellfish and marine mammals.
Mercury may also get transformed into methyl mercury when it’s launched into aquatic environments. As a result of methyl mercury is an natural type of mercury that strikes effectively by way of the meals net, it could possibly attain excessive concentrations in predators which can be tapped into aquatic meals sources. So, larger concentrations of methyl mercury are seen in coastal wolves.
In a examine performed by researchers on the College of Alaska Fairbanks and at Canada’s College of Calgary, printed within the journal Science of the Whole Setting in June 2025, wolves from Nice Island—situated within the Alaska Panhandle area, west of Juneau—are in contrast with the inhabitants on the mainland adjoining to the island, in addition to with wolves from inside Alaska. The very best mercury concentrations had been discovered within the wolves from Nice Island. The researchers state that whereas there might be quite a lot of components driving the upper concentrations of mercury, the mainland inhabitants principally feeds on moose and the odd sea otter.
Because it stays unclear precisely what induced the loss of life of wolf No. 202006, the scientists are additionally doing extra work to find out mercury’s function in impacting wolf well being. Nonetheless, years of collected knowledge present that 70% of the island wolves’ weight-reduction plan is sea otters. It could be that the coastal wolves are consuming so many sea otters that they’re ingesting excessive doses of mercury that accumulate over time. As different populations of wolves in Alaska—in addition to in British Columbia—look like consuming sea otters, this phenomenon is likely to be extra widespread than initially thought.
Coastal wolves that eat sea otters have a lot larger concentrations of mercury than these consuming different prey, equivalent to deer or moose. Some coastal wolves have diets which can be 70% composed of sea otters, so it might be that they’re ingesting the excessive doses of mercury that accumulate in sea otters over time.
Moreover, there’s a possible hyperlink to local weather change, attributable to Alaska’s shrinking glaciers. Glaciers can launch an amazing quantity of mercury; and in coastal Alaska, glaciers are retreating at a few of the most speedy charges on the earth. With that melting, particulate bedrock is launched; and a few of that bedrock accommodates mercury. The destiny of that mercury isn’t recognized. It could get buried in sediments, or it might really be obtainable for conversion to methyl mercury and get into the meals net.
Feminine sea otters display how device use helps them survive a altering world
Within the southern sea otter’s vary of coastal Central California, a few of their most popular prey—equivalent to massive abalone and sea urchins—should not tough to interrupt open. Nonetheless, these meals assets generally dwindle or disappear. This leads sea otters to prey extra typically on clams, crabs, mussels and small marine snails, whose laborious shells can harm a sea otter’s tooth within the means of prying them open.
Tooth situation is necessary for survival as a result of when sea otters’ tooth turn out to be too broken or worn, the animals may starve. Utilizing instruments helps sea otters meet their caloric wants by permitting them to department out into several types of prey.
Sea otters generally use rocks (just like the one on mother’s stomach, right here) as instruments to entry their meals. Those who do use instruments are in a position to eat bigger prey whereas decreasing tooth harm. Females have a tendency to lift offspring, and they’re typically those that cross down tool-use behaviors.
To raised perceive how sea otters use instruments in a quickly altering setting, a analysis staff from the College of California, Santa Cruz; the Monterey Bay Aquarium; and the College of Texas at Austin monitored how sea otters use instruments—equivalent to rocks, shells and trash—to interrupt open prey and recognized hyperlinks to the animals’ dietary patterns and dental well being. The scientists and their volunteer “otter spotters” adopted 196, radio-tagged southern sea otters off the coast of California.
The outcomes, printed within the journal Science in Could 2024, confirmed that feminine sea otters are extra possible to make use of instruments than male sea otters. It might be that the females are utilizing instruments to beat their smaller physique dimension and weaker biting capacity in an effort to satisfy their caloric calls for. Elevating pups takes a number of power, and the females must be environment friendly of their foraging. In truth, females had been in a position to devour prey that had been as much as 35% more durable in contrast with that of males that used instruments. And feminine sea otters had much less tooth harm than male sea otters did. This was the primary time that researchers had discovered that the usage of instruments amongst feminine and male sea otters led to a discount in tooth accidents.
Sea otters courtroom contemplation with their cuteness
Sea otters are the smallest marine mammals in North America. Roughly 90% of the world’s sea otters reside in coastal Alaska. Many reside within the waters surrounding public lands, together with Glacier Bay Nationwide Park, Kenai Fjords Nationwide Park and Kodiak Nationwide Wildlife Refuge. Southern sea otters reside alongside the mainland shoreline of California from San Mateo County to Santa Barbara County and on San Nicolas Island, essentially the most distant of California’s Channel Islands.
Fluffy fur, massive eyes and “puffy cheek buns” contribute to the cuteness of sea otters. Their behavior of floating on their backs and holding fingers in “rafts” provides to their lovable picture.
Hunted to the sting of extinction by fur merchants within the 18th and nineteenth centuries, the few remaining sea otters (estimated to be a mere 1,000 to 2,000 people) had been first protected by the Worldwide Fur Seal Treaty in 1911. Sea otters in america acquired further protections with the passage of the Endangered Species Act and the Marine Mammal Safety Act within the Nineteen Seventies. Immediately, it’s thought that there are about 125,000 to 130,000 sea otters worldwide. The present southern sea otter inhabitants averages round 3,000 people.
I hope you’ll give a thought to them throughout this 12 months’s Sea Otter Consciousness Week. With these massive, furry faces and small, dexterous “fingers” (or forepaws), they’re simply too cute to not.
Right here’s to discovering your true locations and pure habitats,
Sweet
