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. Here are 15 facts about the cute, friendly cetaceans.

1. Dolphins are 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. Dolphins 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 dolphin 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. Dolphins 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. Dolphins make friends with other dolphins.

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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. 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.

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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. Dolphins 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. Dolphins typically give birth to just one calf.

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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. A dolphin's 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. 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. Dolphins are 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 dolphins.

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 the age of 61.

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.

Kodak’s New Cameras Don't Just Take Photos—They Also Print Them

Your Instagram account wishes it had this clout.
Your Instagram account wishes it had this clout.
Kodak

Snapping a photo and immediately sharing it on social media is definitely convenient, but there’s still something so satisfying about having the printed photo—like you’re actually holding the memory in your hands. Kodak’s new STEP cameras now offer the best of both worlds.

As its name implies, the Kodak STEP Instant Print Digital Camera, available for $70 on Amazon, lets you take a picture and print it out on that very same device. Not only do you get to skip the irksome process of uploading photos to your computer and printing them on your bulky, non-portable printer (or worse yet, having to wait for your local pharmacy to print them for you), but you never need to bother with ink cartridges or toner, either. The Kodak STEP comes with special 2-inch-by-3-inch printing paper inlaid with color crystals that bring your image to life. There’s also an adhesive layer on the back, so you can easily stick your photos to laptop covers, scrapbooks, or whatever else could use a little adornment.

There's a 10-second self-timer, so you don't have to ask strangers to take your group photos.Kodak

For those of you who want to give your photos some added flair, you might like the Kodak STEP Touch, available for $130 from Amazon. It’s similar to the regular Kodak STEP, but the LCD touch screen allows you to edit your photos before you print them; you can also shoot short videos and even share your content straight to social media.

If you want to print photos from your smartphone gallery, there's the Kodak STEP Instant Mobile Photo Printer. This portable $80 printer connects to any iOS or Android device with Bluetooth capabilities and can print whatever photos you send to it.

The Kodak STEP Instant Mobile Photo Printer connects to an app that allows you to add filters and other effects to your photos. Kodak

All three Kodak STEP devices come with some of that magical printer paper, but you can order additional refills, too—a 20-sheet set costs $8 on Amazon.

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.

The Reason Dogs Are Terrified of Thunderstorms—And How You Can Help

The face of a dog who clearly knows that a hard rain's a-gonna fall.
The face of a dog who clearly knows that a hard rain's a-gonna fall.
Charles Deluvio, Unsplash

Deafening thunder can be a little scary even for a full-grown human who knows it’s harmless, so your dog’s terror is understandable. But why exactly do thunderstorms send so many of our pawed pals into a tailspin?

Many dogs are distressed by unexpected loud noises—a condition known as noise aversion, or noise phobia in more severe cases—and sudden thunderclaps fall into that category. What separates a wailing siren or fireworks show from a thunderstorm in a dog's mind, however, is that dogs may actually realize a thunderstorm is coming.

As National Geographic explains, not only can dogs easily see when the sky gets dark and feel when the wind picks up, but they can also perceive the shift in barometric pressure that occurs before a storm. The anxiety of knowing loud noise is on its way may upset your dog as much as the noise itself.

Static electricity could also add to this anxiety, especially for dogs with long and/or thick hair. Tufts University veterinary behaviorist Nicholas Dodman, who also co-founded the Center for Canine Behavior Studies, told National Geographic that a static shock when brushing up against metal may heighten your dog’s agitation during a storm.

It’s difficult to nail down why each dog despises thunderstorms. As Purina points out, one could simply be thrown off by a break from routine, while another may be most troubled by the lightning. In any case, there are ways to help calm your stressed pet.

If your dog’s favorite spot during a storm is in the bathroom, they could be trying to stay near smooth, static-less surfaces for fear of getting shocked. Suiting them up in an anti-static jacket or petting them down with anti-static dryer sheets may help.

You can also make a safe haven for your pup where they’ll be oblivious to signs of a storm. Purina behavior research scientist Ragen T.S. McGowan suggests draping a blanket over their crate, which can help muffle noise. For dogs that don’t use (or like) crates, a cozy room with drawn blinds and a white noise machine can work instead.

Consulting your veterinarian is a good idea, too; if your dog’s thunderstorm-related stress is really causing issues, an anti-anxiety prescription could be the best option.

[h/t National Geographic]