15 Delightful Facts About Dolphins

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Dolphins are known for being smart, playful creatures that can learn to perform impressive tricks. But you might not know that dolphins are also champion nappers who have helped the U.S. Navy protect nuclear warheads. We're celebrating National Dolphin Day with these 15 facts about the cute, friendly cetaceans.

1. THEY'RE EXCELLENT NAPPERS.

Since dolphins can't breathe underwater, they need to swim up to the ocean's surface to get air. So how do they sleep without drowning? Essentially, dolphins are champion power nappers. Rather than sleep for several hours at a time, they rest one hemisphere of their brain for 15 to 20 minutes at a time, and they take these "naps" several times each day. By resting one hemisphere of their brain at a time, dolphins can continue swimming, breathing, and watching for predators 24/7.

2. THEY COMMUNICATE WITH CLICKS AND WHISTLES …

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Dolphins communicate with one another underwater by making a variety of vocalizations. To find prey and navigate the ocean, they make clicking sounds, and they "speak" to other dolphins by whistling. Dolphins also produce loud burst-pulse sounds when they feel excited or aggressive, such as when they need to scare off a nearby shark. Some female dolphins also produce a burst-pulse to reprimand their offspring, called calves, for bad behavior.

3. … BUT THEIR LANGUAGE REMAINS A MYSTERY.

Although marine scientists have studied and recorded dolphin vocalizations for decades, many aspects of the animals’ language and how they communicate are still unknown. Scientists have not yet broken down the individual units of dolphin sounds, and they're still searching for a Rosetta Stone that links the animals' vocalizations to their behavior. By using new technologies—including algorithms and high-frequency recorders that work underwater—scientists hope to finally unlock the mystery of the dolphin language.

4. THEY USE ECHOLOCATION TO NAVIGATE.

To know where they are in relation to other objects and animals, dolphins use echolocation (a.k.a. biological sonar). After emitting a series of high-pitched clicks, they listen for the echoes to bounce off their surroundings. Based on these echoes, dolphins can judge where they are in space and determine the size and shape of nearby objects. Besides helping dolphins evade predators, echolocation allows them to trap, catch, and eat fish and squid.

5. THEY MAKE FRIENDS WITH OTHER DOLPHINS …

spotted dolphins swimming
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Dolphins are highly social, and scientists are still discovering fascinating details about how the aquatic mammals socialize with one another. In 2015, scientists at Florida Atlantic University's Harbor Branch Oceanographic Institute published research in the Marine Mammal Science journal about the social networks of dolphins. After spending over six years tracking 200 bottlenose dolphins in Florida's Indian River Lagoon, the scientists discovered that dolphins have friends. Instead of spending equal time with the dolphins around them, the animals actually segregate themselves into friend groups. Just like humans, dolphins seem to prefer the company of certain peers more than others.

6. … AND EACH DOLPHIN RESPONDS TO ITS OWN NAME.

Dolphins aren't swimming around with name tags, but every dolphin has its own unique whistle. Scientists believe that dolphins use these signature whistles for life, and female dolphins may even teach their calves their whistles before they're born. Dolphins use their signature whistles to call out to one another and may be able to remember other dolphins' whistles after decades apart.

7. THERE ARE 44 DIFFERENT DOLPHIN SPECIES.

an orca jumping out of the water
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Although bottlenose dolphins are the most well-known and recognizable, there are 43 other dolphin species. Most species live in temperate and tropical oceans, but a few live in colder oceans or rivers. Depending on their species, dolphins can vary considerably in their physical attributes and behavior. For example, the largest dolphin species, the Orca (also called Killer Whale), can be 30 feet long—10 times longer than the smallest dolphins.

8. THEY DON'T USE THEIR TEETH TO CHEW FOOD.

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Dolphins have teeth, but they don't use their chompers to chew food. Instead, dolphins use their teeth to catch prey (fish, crustaceans, and squid) and swallow it whole. Since they forgo chewing, digestion occurs in their stomach—or, more precisely, in part of their stomach. Dolphins have multiple stomach chambers, one of which is devoted to digestion, while the other chambers store food before it's digested.

9. THEY TYPICALLY GIVE BIRTH TO JUST ONE CALF.

mother and baby dolphin
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Depending on their species, most female dolphins (called cows) carry their babies for nine to 17 months before giving birth to a calf. Interestingly, calves are born tail first, rather than head first, so they don't drown during the birthing process. After nursing for one to two years, a calf typically stays with its mother for the next one to seven years, before mating and having its own calves.

10. THEIR SKIN CAN BE REGENERATED EVERY TWO HOURS.

If you've ever swum with dolphins, you know their skin looks and feels super smooth and sleek. There's a reason for that—a dolphin's epidermis (outer layer of skin) can be sloughed off and replaced with new skin cells as often as every two hours. Because their skin regenerates so often, it stays smooth and, as most scientists believe, reduces drag as they swim.

11. THE U.S. NAVY TRAINS DOLPHINS TO PROTECT NUCLEAR WEAPONS.

A bottlenose dolphin named K-Dog from the Commander Task Unit jumps out of the water in 2003. Commander Task Unit is comprised of special mine clearing teams from The United Kingdom, Australia, and the U.S.
A bottlenose dolphin named K-Dog from the Commander Task Unit jumps out of the water in 2003. Commander Task Unit is comprised of special mine clearing teams from The United Kingdom, Australia, and the U.S.
Brien Aho, U.S. Navy/Getty Images

Despite dolphins' general friendliness, some of them are trained for combat. The Navy Marine Mammal Program at San Diego's Space and Naval Warfare Systems Command (SPAWAR) trains dozens of bottlenose dolphins (as well as sea lions) to help the U.S. Navy. In the past, the U.S. military has used dolphins in conflicts in Vietnam and the Persian Gulf. Today, thanks to their intelligence, speed, and echolocation skills, dolphins are trained to find enemy swimmers, locate underwater mines, and guard nuclear arsenals.

12. THEY'RE NOT THE SAME AS PORPOISES.

To the untrained eye, dolphins and porpoises look nearly identical, and many people mistakenly think that porpoises are a type of dolphin. But the two species belong to completely different families and differ in their physical attributes. So how can you tell them apart? Dolphins, which are usually bigger than porpoises, typically have longer beaks and curved dorsal fins. Porpoises, on the other hand, have more triangular dorsal fins as well as spade-shaped (rather than conical) teeth.

13. HUNTING, OVERFISHING, AND RISING OCEAN TEMPERATURES THREATEN THEM.

Some dolphin species are endangered or functionally extinct (like China's baiji dolphin) due to hunting, overfishing, and pollution. Although dolphin meat is high in mercury, the animals are still hunted for their meat and eaten in parts of Japan and the Faroe Islands of Denmark. Overfishing means that dolphins' food sources are shrinking, and some dolphins get caught up in fishing nets and die. Additionally, climate change and rising ocean temperatures are driving some fish and squid away from their natural habitats, putting dolphins' main food source at risk.

14. A SUPERPOD CAN CONSIST OF MORE THAN 1000 DOLPHINS.

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Dolphins live in groups, called pods, that typically contain dozens or hundreds of dolphins. By swimming in a pod, dolphins work together to hunt prey, evade predators, and care for sick or injured members. But different pods can also merge, forming a superpod of more than 1000 dolphins. Superpods are typically temporary and occur in parts of the ocean with plentiful food (and less competition for tasty squid).

15. THE OLDEST DOLPHIN IN CAPTIVITY LIVED TO 61 YEARS OLD.

Dolphin lifespan varies greatly by species. Most dolphins in the wild live for a few decades, while those in captivity have a drastically reduced lifespan and may live for only a few years. So it's all the more shocking that the oldest dolphin in captivity lived to be a sexagenarian. Nellie, a bottlenose dolphin who lived in a marine entertainment park in Florida, was born in 1953. She appeared on TV shows and commercials and performed tricks for the park's attendees before passing away in 2014.

13 Fascinating Facts About Bees

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iStock.com/florintt

Sure, you know that bees pollinate our crops and give us honey. But there's so much more to these buzzing insects than that.

1. Bee stings have some benefits.

A toxin in bee venom called melittin may prevent HIV. Melittin can kill HIV by poking holes into the virus's protective envelope. (Meanwhile, when melittin hitches a ride on certain nanoparticles, it will just bounce off normal cells and leave them unharmed.) Scientists at Washington University in St. Louis hope the toxin can be used in preventative gels.

Bee stings may also ease pain caused by rheumatoid arthritis. Researchers at the University of Sao Paulo found that molecules in bee venom increase your body's level of glucocorticoid, an anti-inflammatory hormone.

2. Bees work harder than you do.

During chillier seasons, worker bees can live for nine months. But in the summer, they rarely last longer than six weeks—they literally work themselves to death.

3. When bees change jobs, they change their brain chemistry.

bees flying to a hive
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Bees are hardwired to do certain jobs. Scout bees, which search for new sources of food, are wired for adventure. Soldier bees, discovered in 2012, work as security guards their whole life. One percent of all middle-aged bees become undertakers—a genetic brain pattern compels them to remove dead bees from the hive. But most amazingly, regular honeybees—which perform multiple jobs in their lifetime—will change their brain chemistry before taking up a new gig.

4. Their brains defy time.

When aging bees do jobs usually reserved for younger members, their brain stops aging. In fact, their brain ages in reverse. (Imagine if riding a tricycle didn't just make you feel young—it actually made your brain tick like a younger person's.) Scientists at Arizona State University believe the discovery can help us slow the onset of dementia.

5. Bees are changing medicine.

To reinforce their hives, bees use a resin from poplar and evergreen trees called propolis. It's basically beehive glue. Although bees use it as caulk, humans use it to fight off bacteria, viruses, and fungi. Research shows that propolis taken from a beehive may relieve cold sores, canker sores, herpes, sore throat, cavities, and even eczema.

6. Bees can recognize human faces.

Honeybees make out faces the same way we do. They take parts—like eyebrows, lips, and ears—and cobble them together to make out the whole face. It’s called "configural processing," and it might help computer scientists improve face recognition technology, The New York Times reports.

7. Bees have personalities

Even in beehives, there are workers and shirkers. Researchers at the University of Illinois found that not all bees are interchangeable drones. Some bees are thrill-seekers. Others are a bit more timid. A 2011 study even found that agitated honeybees can be pessimistic, showing that, to some extent, bees might have feelings.

8. They get buzzed from caffeine and cocaine.

bumblebee on a flower
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Nature didn't intend for caffeine to be relegated to your morning pot of coffee. It's actually a plant defense chemical that shoos harmful insects away and lures pollinators in. Scientists at Newcastle University found that nectar laced with caffeine helps bees remember where the flower is, increasing the chances of a return visit.

While caffeine makes bees work better, cocaine turns them into big fat liars. Bees "dance" to communicate—a way of giving fellow bees directions to good food. But high honeybees exaggerate their moves and overemphasize the food's quality. They even exhibit withdrawal symptoms, helping scientists understand the nuances of addiction.

9. Bees have Viking-like navigation techniques.

Bees use the Sun as a compass. But when it's cloudy, there's a backup—they navigate by polarized light, using special photoreceptors to find the Sun's place in the sky. The Vikings may have used a similar system: On sunny days, they navigated with sundials, but on cloudy days, sunstones—chunks of calcite that act like a Polaroid filter—helped them stay on course.

10. Bees can solve hairy mathematical problems.

Pretend it's the weekend, and it's time to do errands. You have to visit six stores and they're all at six separate locations. What's the shortest distance you can travel while visiting all six? Mathematicians call this the "traveling salesman problem," and it can even stump some computers. But for bumblebees, it's a snap. Researchers at Royal Holloway University in London found that bumblebees fly the shortest route possible between flowers. So far, they're the only animals known to solve the problem.

11. Bees are nature's most economical builders.

In 36 BCE, Marcus Terentius Varro argued that honeycombs were the most practical structures around. Centuries later, Greek mathematician Pappus solidified the "honeycomb conjecture" by making the same claim. Almost 2000 years later, American mathematician Thomas Hales wrote a mathematical proof showing that, of all the possible structures, honeycombs use the least amount of wax. And not only are honeycombs the most efficient structures in nature—the walls meet at a precise 120-degree angle, a perfect hexagon.

12. Bees can help us catch serial killers.

Serial killers behave like bees. They commit their crimes close to home, but far enough away that the neighbors don't get suspicious. Similarly, bees collect pollen near their hive, but far enough that predators can't find the hive. To understand how this "buffer zone" works, scientists studied bee behavior and wrote up a few algorithms. Their findings improved computer models police use to find felons.

13. Bees are job creators.

beekeeper working with bees
iStock/Milan_Jovic

The average American consumes roughly 1.51 pounds of honey each year. On top of that, the U.S. Department of Agriculture estimates that honeybees pollinate up to 80 percent of the country's insect crops—meaning bees pollinate over $15 billion worth of crops each year.

This article was updated and republished in 2019.

25 Benefits of Adopting a Rescue Dog

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iStock.com/Manuel-F-O

According to the ASPCA, 3.3 million dogs enter shelters each year in the United States. Although that number has gone down since 2011 (from 3.9 million) there are still millions of dogs waiting in shelters for a forever home. As May 20th is National Rescue Dog Day, here are 25 benefits of adopting a shelter dog.

1. Adopting a dog means you won't be supporting puppy mills.

A closeup of a dog's nose sticking out from between green bars.
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If you go to a pet store or to a disreputable breeder to buy that adorable puppy, it's entirely possible that it's from a puppy mill, where dogs are kept in terrible conditions. By adopting a rescue, you can help lower the demand for puppies from puppy mills.

2. You can find almost any breed you want.

A beagle puppy standing on a stone walkway.
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Is your heart set on a specific breed? There's a wide network of breed-specific rescues out there. Just spend a little time online and you can get the dog of your dreams without resorting to buying from puppy mills.

3. Shelter dogs are eager to follow your lead.

A woman holding up her finger to a dog.
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A 2016 study that appeared in Journal of Veterinary Behavior: Clinical Applications and Research analyzed problem solving in dogs in homes (what they called "pet dogs") versus shelter dogs. The researchers found that although pet dogs are better at following human pointing, shelter dogs "seem to be more socially driven to gaze and interact with humans" when compared with pet dogs, which they say is likely due to the shelter dogs' "generally limited and poor-quality contact with humans." But the researchers also pointed out that with increased human exposure, the shelter dogs were trainable.

4. A rescue dog might help you get a date.

Two people from the knees down standing close together with a black and white dog between them.
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According to Slate, one survey found that "82 percent of people [felt] more confident approaching an attractive person if they had their dog with them." Another study cited by Slate found that in the modern world of dating apps, people with dogs look more approachable and happy than those who are dogless.

5. You can share your audiobook collection with them.

A young girl reads a book to her Pomeranian.
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There have been several studies on the best ways to calm dogs in kennels [PDF]. Classical music seems to work well, but a 2016 study found that compared to other "auditory conditions," kenneled dogs were more relaxed while audiobooks were playing. Cesar Milan then did his own tests and found that 76 percent of his volunteer dogs were more relaxed at home while listening to audiobooks—and teamed up with Audible to create a specialized audiobook service. Just be careful: soon your rescue pup will be better read than you.

6. Rescue dogs can transform in dramatic ways in a forever home.

A happy dog with his tongue out sitting in a field of flowers.
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Thanks to those heart-wrenching ASPCA/Sarah McLachlan commercials, everyone is familiar with how sad a dog can appear in a shelter. But once adopted, dogs' attitudes can change dramatically. In 2008, Italian researchers published a paper about a shelter dog named Daisy that they placed into a facility for people suffering from Alzheimer’s disease. Although in the shelter Daisy had groomed so much that she developed a skin lesion, in the six months that she lived at the facility, her over-grooming lessened, she was healthy, and she "displayed no aggressive or sexual behavior, even when in heat." And the calming effect seemed to go both ways: the researchers reported, the people in the facility experienced "many positive effects of Daisy's presence."

7. Shelter pets come with benefits.

A dog running through the grass with an orange ball in its mouth.
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Whether you get your pet at a breed-specific rescue or from a normal shelter, you'll often have access to resources about your fuzzy new family member, and maybe even classes on how best to take care of them.

8. Shelter dogs are typically up-to-date on all their shots.

A vet giving a shot to a golden retriever puppy.
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Depending on the shelter, shelter dogs may already be vaccinated and microchipped (or the shelter will perform these services for a small fee)—which means you can get straight to cuddling your new pet instead of making vet appointments.

9. Shelter dogs may also already be spayed or neutered.

A vet looking into a dog's ear.
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More than half of states have laws requiring "releasing agencies" (a.k.a. shelters) to spay or neuter dogs they adopt out. While the pet sometimes isn't fixed until you adopt it, frequently it's already been spayed or neutered. Check with your local adoption center.

10. By adopting a dog, you're helping to keep the unwanted pet population down.

A lazy bulldog lying on a rug.
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If you happen to adopt a dog that isn't fixed, you can still help prevent pet overpopulation (especially in the wild) by keeping it in the house and away from other unfixed dogs of the opposite sex. (But seriously, get your pets fixed!)

11. Rescue dogs may be easier to housetrain.

A small dog holding a leash in its mouth.
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Many adult shelter dogs are already housebroken when you adopt them. But because the dog may have a history that prevented such training (such as never being allowed inside the house), you shouldn't go in expecting a house-trained pet. If your new pupper isn't house-trained, there are resources out there that can help you reach that goal; many say that adult dogs have an easier time getting the hang of it.

12. Adopt and older dog and you can skip the puppy stage.

A dachshund puppy plays with a shoe outside in grass.
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Yes, puppies are adorable. They're also full of energy and require a lot of time, training, attention, and patience. It can be tough to fit an energetic puppy into a hectic life. Adopting an older dog from a shelter allows you to skip the puppy stage altogether, which can mean an easier transition from not having a pet to being a pet owner. It also (hopefully) means you may avoid having your slippers, running shoes, pillows, furniture, and doors gnawed on by sharp little puppy teeth.

13. If you adopt an older dog, you'll have a better idea of their temperament.

An older dog sitting in the grass with his tongue sticking out.
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An analysis of many studies found that the "personality" of an adult dog is fairly consistent. Puppies, on the other hand, can change personality a fair amount, especially when it comes to "responsiveness to training, fearfulness, and sociability." So by getting an adult dog, you have a better idea of what the animal's personality is truly like.

14. A shelter can help match you with a dog that best reflects your personality.

A red haired woman holding a white dog, both laughing.
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Because adult dogs are generally more fixed in their personalities, many adoption centers have matching programs that help the process of pairing dog and human. The ASPCA claims the programs have dramatically improved successful adoptions at some shelters.

15. You'll feel more involved in the community.

A businessman walking his dog and talking to another dog owner.
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According to a 2013 study, dog owners over 50 who walked their dogs felt a higher sense of community. So adopting a dog can help you connect to your neighbors.

16. A dog can improve your health.

Woman working on her computer getting a kiss on the face from her dog.
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A study of Mexican dog owners versus non-dog owners found that the dog owners felt that they were healthier: "Compared to non–dog owners, the dog owners' scores were significantly lower for psychosomatic symptoms and stress and were higher for general health, vitality, emotional role, absence of bodily pain, social functioning, and mental health."

17. Your kids will play more if you have a dog.

A group of kids petting a dog.
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It's not just adults who experience health benefits from having a dog; another study found that child dog walkers played outside more and were more likely to walk in the neighborhood.

18. Adopting a pet helps small wild animals.

A dog looking for a squirrel up in a tree, but the squirrel is on the other side of the tree.
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As one of the most common predators in human areas, dogs can easily do great harm to local wildlife. By keeping dogs out of the wild (whether that's the city or the countryside), you can help reduce the numbers of truly wild animals that are preyed upon by what are supposed to be pets.

19. Adopting a dog can limit the spread of disease.

A yellow lab staring up at the camera.
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Feral dogs can also have disastrous effects on wild animals in regards to disease. For instance, the black-footed ferret was nearly driven to extinction by canine distemper. By keeping dogs out of the environment and up-to-date on all their necessary shots and vaccinations, adopters help many other animals, too.

20. You could have a movie star on your hands.

A dog wearing a bowtie, standing behind a slate for a movie.
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A surprising number of actual canine movie stars came from shelters. The original Benji was adopted from a shelter; Rudy, one of the 22 dogs that played Marley in the film Marley and Me, was just 24 hours away from being put down before he was rescued; and Spike, the star of Old Yeller, was adopted from Van Nuys Animal Shelter, supposedly for $3.

21. A rescue dog might have experience living in a home, making the move from shelter to your home an easier transition.

A dog on its back on a carpet.
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Some shelters have foster programs, where the dog is sent out to live with a volunteer in an actual house. Not only does this give the dog a chance to be away from the shelter, but it gives the humans looking after the pup a chance to see how the dog reacts in a less controlled environment—hopefully making the future forever home transition easier.

22. Even volunteering to foster has its benefits.

A woman walking a dog in the park.
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If you're not quite ready to adopt, consider fostering, which has a number of benefits for you and for the dogs you're housing. According to one researcher, overweight participants in a "loaner" dog walking program lost an average of 14 pounds because they felt "the dogs need us to walk them." Other participants in a community dog walking program were inspired to increase their exercise even when they weren't walking dogs.

23. You can help shelters modernize.

A chihuahua sitting on a cushion in an animal shelter.
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Shelters across the country are modernizing their facilities—which can sometimes be a very expensive prospect. The adoption fee you pay to the shelter to take your dog home will help the facility get the resources to give future dogs a better shelter experience.

24. By adopting a dog, you're saving at least one life.

A happy dog with its tongue sticking out lying on flowers.
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By giving a dog in a shelter a second chance, you can make sure it has a great life.

25. In reality, you're probably saving more than one life.

A dog running with a stick in its mouth; all four feet are off the ground.
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By adopting a dog, you open up a space in the shelter that can be filled by another future pet. And by supporting your local shelter, you help their mission to save many more.

But remember, a pet of any kind is a massive commitment. Some estimate that "more than 20 percent of people who leave dogs in shelters adopted them from a shelter." And studies have found that much of the problem is people not knowing what they're getting into. So make sure that you have the time and energy to devote to a pet, and do your research before adopting.

This story has been updated for 2019.

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