Dolphins never cease to amaze. As researchers delve into the underwater world of these brilliant cetaceans, they’re learning that these creatures are full of surprises, from their intricate social lives to their intelligence. Here are just some of the ways dolphins are exceptional, both physically and mentally.
1. Dolphins Evolved From Land Animals
Dolphins didn’t always live in the water. The ancestors of these marine animals were even-toed ungulates, which had hoof-like toes at the end of each foot and roamed across the land. But about 50 million years ago, these ancestor animals decided that the ocean was a better place to live and evolved into the dolphins we know today.1
The evidence for this evolutionary history can be seen in dolphins’ skeletons today: Adult dolphins have remnant finger bones in their flippers, as well as vestigial leg bones.
- They Can Stay Awake for Weeks
A 2012 study found that dolphins were able to successfully utilize their echolocation abilities for 15 days straight — without any sleep or rest.2 In other words, dolphins don’t need much sleep at all. They manage this by resting one half of their brain at a time, a process called unihemispheric sleep.
Though shocking, this ability makes sense. Dolphins need to go to the ocean’s surface to breathe, so they have to stay constantly awake to be able to take breaths and avoid drowning. It also acts as a defense mechanism, protecting them from potential predators.
Meanwhile, baby dolphins don’t sleep at all for weeks after they are born. Researchers think this is an advantage because it helps the calf to better escape predators and keep its body temperature up while its body accumulates blubber.3 It’s also believed that this lack of sleep encourages brain growth.
- Dolphins Don’t Chew Their Food
If you’ve ever watched a dolphin eat, you may have noticed that they seem to gulp down their food. That’s because dolphins don’t chew; they use their teeth only to grip prey. At most, dolphins will shake their food or rub it on the ocean floor to tear it into more manageable pieces.
One theory for why they’ve evolved to do away with chewing is because they need to quickly consume their fish dinner before it can swim away. Skipping the process of chewing ensures their meal doesn’t escape.
- Dolphins Are Utilized by the U.S. Military
Since the 1960s, the U.S. Navy has utilized dolphins to detect underwater mines. Much like bomb detection dogs work by smell, dolphins work by echolocation. Their superior ability to scan an area for particular objects allows them to zero in on mines and drop markers at the spots. The Navy can then find and disarm the mines. The echolocation skills of dolphins far outstrip any technology people have come up with to do the same job.
However, these Navy programs have been highly controversial, as animal rights advocates have long opposed the use of dolphins for military purposes. Concerns include the stresses dolphins experience with sudden transportation and transplantation to new areas, muzzles that prevent them from foraging while working, and the risk of accidental detonation of a mine. Though the U.S. Navy Marine Mammal Program maintains that it complies with federal laws regarding the care of their dolphins, activists have continued to fight against exploitation.4
- Dolphins Use Tools
Researchers discovered that a population of dolphins living in Shark Bay, Australia uses tools.5 Some searched for cone-shaped sea sponges and tore them free from the ocean floor. Then, they carried the sponges on their beaks to a hunting ground, where they used them to probe the sand for fish that are hiding.
The behavior is called "sponging," and it is not the first example of tool use in cetaceans. The researchers think this helps protect their sensitive snouts while they hunt.
While this demonstrates dolphins’ intelligence, it also shows evidence of their social skills. The practice is passed down from mother to daughter, which indicates the existence of culture among nonhumans.
- Dolphins Form Friendships Through Shared Interests
Studying the same group of dolphins in Shark Bay, another group of researchers discovered that the dolphins formed friendships based on a shared interest — in this case, sponging.6 This behavior is less common in male dolphins, so by focusing on them, the researchers discovered a new way it informs dolphin relationships. Male spongers spent more time associating with other male spongers than non-spongers, indicating that a shared interest in the practice was an important factor in the formation of social bonds.
- Dolphins Call Each Other by Name
We know dolphins communicate, but a study published in 2013 revealed that their communication skills go as far as using names.7 Dolphins within pods have their own "signature whistle," which acts as a unique identity signal just like a name.
Researchers recorded dolphins’ signature whistles and played them back to the pod. They found that the individuals only responded to their own calls, sounding their own whistle back in acknowledgment.
What’s more, the dolphins didn’t respond when the signature whistles of dolphins from strange pods were played, indicating that they’re looking for and responding to specific calls.
Considering dolphins are a highly social species with the need to stay in touch over distances, it makes sense that they would have evolved to use "names" much in the same way people do.
- Dolphins Work Together as a Team
In addition to communicating with names, dolphins can also work together as a team, an ability previously thought to be unique to humans.
Research conducted in 2018 found that dolphins were able to synchronize their actions to solve a cooperation task and receive a reward.8 The test involved getting a pair of dolphins to press two separate underwater buttons at the same time. Once the dolphins figured out that the task was cooperative, they succeeded.
- Dolphins Get High on Fish Toxins
Pufferfish carry strong toxins which, if consumed in small doses, act as a narcotic. Dolphins have discovered this, and they’ve used this information for recreational benefit.
In 2013, the BBC filmed dolphins gently playing with a pufferfish, passing it between pod members for 20 to 30 minutes, then hanging around at the surface seemingly mesmerized by their own reflections.
Rob Pilley, a zoologist who also worked as a producer on the series, was quoted in The Independent: "This was a case of young dolphins purposely experimenting with something we know to be intoxicating … It reminded us of that craze a few years ago when people started licking toads to get a buzz."
- There Are 36 Dolphin Species
There is more than just one type of dolphin — in fact, the dolphin family Delphinidae contains 36 species. This also means that the conservation status of dolphins differs greatly. Many species, including the well-known common bottlenose dolphin (Tursiops truncatus), are thriving. Others, despite being protected under the Marine Mammal Protection Act and Endangered Species Act, maintain varying degrees of concern, such as the critically endangered baiji (Lipotes vexillifer).9
One way you can help protect vulnerable dolphin species is to avoid single-use plastics, as these items end up in oceans and can harm the animals. You can also be mindful to only buy fish from sustainable fisheries (or avoid buying fish altogether) and join beach-cleanup initiatives.