Otters playing happily in the water is an endearing sight. Their wet fur glistening as they frolic and float, fully immersed in their aquatic domain. However, while wet otters may look cute, there’s more to these semi-aquatic mammals than meets the eye.
If you’re short on time, here’s a quick answer to what makes otters wet: Otters have water-resistant fur that keeps their skin dry, but their outer guard hairs can still get soaked. They also lack insulating fat, so they must keep moving in cold water to stay warm.
In this comprehensive guide, we’ll uncover what makes otters wet, how they stay warm in chilly waters, their grooming habits, how long they can stay in water before getting too cold, and much more regarding these adorable wet creatures.
The Composition of Otters’ Fur
The Insulating Underfur Layer
Otters have two types of fur that keep them warm while swimming in cold waters. The underfur layer is very dense and soft, with about 150,000 to 165,000 hairs per square centimeter. This traps air close to the otter’s skin to provide insulation against cold water and air temperatures.
In fact, otters have the thickest underfur of any mammal in the world! The air trapped within an otter’s fur only allows about 2% of the body heat to escape into the water, allowing otters to swim and fish in icy conditions that would cause hypothermia in most other mammals.
The Water-Repellent Guard Hairs
The second layer of otter fur consists of longer guard hairs that are water repellent. These guard hairs catch bubbles of air when the otter dives, further helping insulate it from the cold water. Guard hairs vary in length – they are usually shortest on the otter’s underside for streamlined swimming, and longest around the tail, hips, and head which need extra protection and warmth.
The guard hairs are constantly oiled and groomed by the otter to maintain their water-resistance. This allows otters to trap dry air within their fur even when completely submerged. In fact, studies show an otter pelt still has 40% dry insulating air even after being submerged for over 2 hours!
Why Otters Don’t Rely on Blubber for Warmth
High Metabolism and Calorie Intake
Unlike seals or whales, otters do not have a thick layer of blubber or fat to keep them warm in cold water. Instead, they have extremely high metabolisms and calorie intakes to generate body heat. An otter’s metabolic rate is up to three times higher than a typical mammal of the same size.
To fuel this, otters consume up to 25% of their body weight in food per day, equivalent to a 150-pound human eating around 40 pounds of food in one day!
With such high energy requirements, otters spend most of their awake time hunting and eating. Sea otters dine on sea urchins, crabs, clams, and small fish; while river otters feed on fish, crayfish, and amphibians.
Their high-protein aquatic diet provides the nutrients and calories they need to thrive. Unlike blubber, this internal heat source allows them to be more agile swimmers to catch prey.
Continual Movement to Generate Body Heat
Otters also rely on continual movement to generate warmth. They have little insulating fat and a dense fur coat that traps air close to their skin when dry. Otter fur consists of two layers —a short undercoat overlaid with longer guard hairs.
There are about 1 million hairs per square inch in an otter pelt, creating ample air spaces for insulation.
However, if water seeps to their skin, otters can quickly get chilled. To prevent this, otters are constantly moving — both in and out of the water. This includes frequent grooming to squeeze out damp air and restore insulating air pockets throughout their coat.
River otters may also use a playful “cracking people up”☺️ behavior, sliding repeatedly down muddy or snowy banks. This full-body motion helps keep blood flowing to their entire skin surface for warming.
Grooming Habits for Wet Fur
Frequent Rubbing and Rolling
Wet otters have some clever grooming habits to help keep their fur clean and dry. One of the main things they do is rub and roll against various surfaces. Otters will find grass, moss, leaves, or sandy areas and vigorously rub their bodies back and forth.
This helps squeeze water out of their dense underfur layer and absorbs moisture into the vegetation or sand. Otters have also been observed doing somersaults and log rolls to shake water off and fluff up their coats. Their dexterous paws further help them rub and scratch at hard-to-reach spots.
This frequent rubbing and rolling is essential after swimming or in wet conditions to restore the insulating air pockets in their fur.
Use of Rocks to Remove Debris
Another interesting grooming behavior of otters is their use of rocks to remove debris and parasites from their fur. They will find a flat rock along the shoreline and repeatedly rub and pound their coats against the surface.
This helps scrape off any mud, leaves, twigs, or other matter stuck in their fur. The rock can also be used to squash and remove external parasites like ticks. Some otters will even bang open clams and mussels against the rock to get at the soft meat inside and then use the empty shells to groom themselves after!
An otter’s rock is a prized tool they often carry with them in a special pouch under their arm as they swim and hunt. Having this mobile grooming station helps keep their coats clean and tidy, which is essential for maintaining proper insulation in cold waters.
Time Limits for Wet Fur Before Hypothermia
Depends on Air and Water Temperatures
Otters can quickly become hypothermic if their dense fur stays wet for too long (Yoxon and Yoxon 2014). How long they can tolerate wet fur depends on both the air temperature and water temperature. In cold water (below 10°C/50°F), an otter’s fur loses its insulating ability when wet.
Prolonged swimming in cold water will cause body heat loss, so otters try to get out frequently to dry off and warm up. They may only swim for a few minutes at a time in very cold water before getting out to groom and dry their coats.
Otters are more vulnerable to hypothermia in cold air temperatures. If air temperature is below freezing, wet otters can succumb to hypothermia in less than 15 minutes (Serfass et al. 2015). Otters will seek shelter in dens or under vegetation when emerging wet in winter conditions.
Grooming and rolling vigorously can help dry their dense underfur quickly.
In more moderate air temperatures (10-20°C/50-68°F), a wet otter may tolerate 30-60 minutes before getting too chilled (Yoxon and Yoxon 2014). But they will still actively work to dry themselves off by rubbing against grass or rocks.
Otters are built to handle periodic soaking – their feathers trap air even when wet, providing some insulation. But allowing their dense underfur to stay saturated for too long can be dangerous.
Behavioral Signs of Getting Too Cold
Otters exhibit certain behaviors when their body temperature drops dangerously low from wet fur (Serfass et al. 2015):
- Shivering
- Lethargy and reduced activity
- Seeking warm shelters
- Curling up into a ball
- Whimpering or crying out
Young otter pups are especially vulnerable to hypothermia. If you observe lethargic, shivering, or vocalizing otter pups, they may be in distress from getting too chilled and require immediate intervention (Yoxon and Yoxon 2014).
Adult otters are well adapted to periodic soaking and can usually dry themselves effectively. But very cold temperatures, high winds, illness, or injury can impair an otter’s ability to warm up and dry off.
If you see prolonged shivering, lethargy or weakness in an otter, contact a wildlife rehabilitator immediately.
Other Interesting Facts About Wet Otters
Playing Games While Wet
Otters love to play while wet, whether they are swimming in rivers or the ocean. Their play often involves unique games that allow them to showcase their swimming talents. One popular game is “king of the log”, where otters will wrestle and chase each other off a floating log to claim dominance.
Otters may also play “follow the leader” as they dive and twirl through kelp forests. These joyful games strengthen social bonds between otters. According to the Otter World wildlife site, young sea otters especially enjoy wrestling, somersaulting, and sliding through the water just for the fun of it.
Unique Scent Glands for Communication
Wet otters possess specialized scent glands that allow them to communicate important information. According to marine biologists, otters have scent glands under their tail that secrete oils conveying reproductive status.
By slapping this musky oil on logs or rocks, male otters alert other otters to their dominance over a territory. Mother otters also mark preferred locations for raising pups. Incredibly, the signatures from these glands can persist underwater for up to three weeks!
Researchers believe secondary scent glands on the otter’s paws may impart traces last even longer when otters dig pits to roll in. So whether at play or marking territories, wet otters make quite an impression!
Conclusion
In the end, wet otters perfectly exemplify the amazing adaptations mammals can evolve for semi-aquatic living. With their dual-layer fur, high metabolism and constant motion, otters are exquisitely equipped to exploit cold waters that would chill most predators.
Through continual grooming and scent communication, they maintain social bonds even when wet. We hope this guide gave you a deeper appreciation for these delightful water dogs of the animal kingdom!
