68 Interesting Facts about Dolphins

By Karin Lehnardt, Senior Writer
Published April 11, 2017
  • When humans take a breath, they replace only 15% of the air in their lungs with fresh air. When dolphins take a breath, they replace 90% of the air in their lungs with fresh air.[4]
  • Dusky and spinner dolphins can leap 20 feet (6.1 m) or higher in the air. In fact, spinner dolphins get their name from spinning and somersaulting above the waves.[4]
  • Scientists believe that dolphins don’t ever fall into a deep sleep; therefore, they probably don’t dream.[4]
  • Called “re-entrants,” dolphins once lived on land and looked and behaved something like a small wolf but with five hoof-like toes on each foot instead claws. Dolphins also have remnant finger bones in their flippers, a forearm, wrists, and a few remnant leg bones deep inside their bodies.[2]
  • Dolphins can recognize themselves in the mirror, and they love to admire themselves.[9]
  • Killing a dolphin in ancient Greece was considered sacrilegious and was punishable by death. The Greeks called them hieros ichthys, or “sacred fish.”[3]
  • Dolphins were revered in ancient Rome and Greece
  • In Rome, dolphins were thought to carry souls to the “Islands of the Blest,” and images of dolphins have been found in the hands of Roman mummies, presumably to ensure their safe passage to the afterlife.[3]
  • There are 40 existing species of dolphins. Most species live in shallow waters of tropical and temperate oceans. Five species live in rivers.[2]
  • A two-headed dolphin was found in western Turkey in 2014.[11]
  • Famous philosophers such as Pliny, Herodotus, Aelian, and Aristotle commented on the compassion and friendly and almost moral nature of dolphins.[6]
  • The narwhal dolphin has a large ivory tusk (like a unicorn), which is often poached. The only remaining populations are in the Greenland Sea and Baffin Bay.[6]
  • Dolphins have the longest memory in the animal kingdom.[4]
  • Just one-half of a dolphin’s brain goes to sleep at a time.[10]
  • Dolphins can talk and understand each other over the phone.[12]
  • Some dolphins can understand as many as 60 words, which can make up 2,000 sentences. They also show signs of self-awareness.[6]
  • Just a tablespoon of water in a dolphin’s lung could drown it. A human could drown if two tablespoons of water were inhaled into the lungs.[3]
  • The dolphin brain is even more “folded” than humans’ and was this way millions of years before the first appearance of humans. Scientists often measure intelligence by the number of brain “folds.”[10]
  • The happiness of the bee and the dolphin is to exist. For man it is to know that and to wonder at it.

    - Jacques Yves Cousteau

  • A baby dolphin is born tail-first to prevent drowning. After the mother breaks the umbilical cord by swiftly swimming away, she must immediately return to her baby and take it to the surface to breathe.[7]
  • A female dolphin will assist in the birth of another’s baby dolphin, and if it is a difficult birth, the “midwife” might help pull out the baby. Other dolphins, including bulls, will swim around the mother during birth to protect her.[3]
  • Air can be expelled from a dolphin’s blowhole at speeds topping 100 mph.[3]
  • Dolphins avoid getting the bends by completely collapsing their ribcage, which forces the air pressure out of the lungs and into the windpipe and complex air chambers below its blowhole.[6]
  • A dolphin’s sonar or echolocation is rare in nature and is far superior to either the bat’s sonar or human-made sonar.[3]
  • With echolocation, dolphins can distinguish between a steel ball that is 2½ inches in diameter and one that is 2¼ inches in diameter.[3]
  • A baby dolphin must learn to hold its breath while nursing.[4]
  • A baby dolphin must learn to hold its breath while nursing
  • Blocking off a dolphin’s ears with suction cups hardly affects its hearing, yet if its lower jaw is covered with a rubber jacket, a dolphin will have trouble hearing. This has led scientists to believe sound may be carried from the water to its inner ear through the lower jawbone or even its entire body.[3]
  • A dolphin can produce whistles for communication and clicks for sonar at the same time, which would be like a human speaking in two voices, with two different pitches, holding two different conversations.[2]
  • A dolphin can make about 700 clicking sounds per second. The clicks come from deep inside the dolphin’s head, underneath the blowhole. Scientists call this area the “monkey lips.”[4]
  • The bulging part of a dolphin’s head contains an organ called the melon, which is filled with liquid fat. It acts as a lens, which focuses the dolphin’s clicks into a narrow beam of sound.[3]
  • Dolphins get water from the foods they eat, so they don’t drink. They have the same reaction to drinking salt water as humans do: it would dry them out until they died of dehydration.[4]
  • Among the different species of dolphins, life spans range between 12 and 80 years. Bottlenose dolphins live into their 50s, and orcas can live into their 80s. Typically, the bigger the dolphin, the longer the lifespan.[10]
  • Giraffes, humans, and dolphins all have seven vertebrae in their neck. Saltwater dolphins have at least their first two neck vertebrae fused, which allows them to torpedo through the water at high speeds. River dolphins must be able to twist around river bends, so their vertebrae are not fused.[2]
  • The blowhole is an evolved nose that has moved upward to the top of the dolphin’s head
  • The blowhole is an evolved nose that has moved upward to the top of the dolphin’s head.[2]
  • Because dolphins are connected to their mothers by an umbilical cord inside a womb, dolphins have belly buttons.[5]
  • A dolphin spends most of its life holding its breath.[4]
  • Every year, a dolphin’s teeth grow a new layer, similar to the rings inside a tree trunk. Scientists can tell how old a dolphin is from the layers on its teeth.[3]
  • Dolphins can move each eye independently. They can move each eye up, down, forward, and backward, giving them nearly 360 degrees of vision.[4]
  • Dolphins have hair at one point in their life cycle. Dolphins in the womb have a line of tiny hairs around their upper and lower lips, which typically fall out before birth. No mustaches have ever been discovered on a dolphin.[2]
  • Dolphin meat is sold in stores throughout Japan. Japanese dolphin or “drive” hunts kill nearly 20,000 dolphins, porpoises, and small whales every year.[1]
  • A 260-pound dolphin eats approximately 33 pounds of fish daily without gaining weight, which is akin to a human eating 15 to 22 pounds of steak a day.[6]
  • Unlike most wild animals, dolphins spend a lot of time enjoying sex and foreplay that is not determined by the urge to procreate or being “in season.”[2]
  • It is illegal to touch or feed a wild dolphin in U.S. waters.[4]
  • It is illegal to touch or feed a wild dolphin in U.S. waters
  • No one knows exactly why dolphins beach themselves. But because dolphins may use the magnetic field of the earth to navigate their way, some scientists believe that some places where dolphins strand have an abnormal magnetic field.[6]
  • Dolphins typically do not live alone, but rather in schools or pods. They have a complex social structure and seem to have a wide range of emotions, including humor. Large pods can have 1,000 members or more.[2]
  • Some scientists think that dolphins can also use their high-pitched sounds to stun or paralyze fish while hunting.[3]
  • Dolphins do not breathe automatically as humans do and will die if given a general anesthetic. They must sleep at the surface of the water with their blowholes exposed.[10]
  • Images of dolphins have been found carved far within the desert city of Petra, Jordan.[2]
  • The dolphin’s most dangerous enemy is humans.[6]
  • Unlike a fish, which moves its tail from side to side, a dolphin swims by moving its tale (made up of flukes) up and down. A dolphin carries more oxygen in its blood than a fish and can swim longer; hence, dolphins are better adapted to the sea than are any fish.[3]
  • Dolphins are better adapted to the sea than most fish
  • Dolphin teeth are used for grasping, not chewing. They have no jaw muscles for chewing.[2]
  • In 2006, the Yangtze River dolphin was named functionally extinct.[4]
  • Dolphins’ sonar seems not to detect the fine threads of fishing nets, and millions of dolphins have drowned as a result of becoming entangled.[6]
  • Dolphins cannot swim backward, which makes it difficult for them to escape fishing nets. If they can’t get to the surface, they can drown in a matter of minutes.[6]
  • In 1971, the Navy dispatched a team of dolphins “armed” with large carbon-dioxide-filled hypodermic needles strapped to their beaks to guard a U.S. Navy base in Vietnam. The dolphins were trained to deliver a fatal injection in humans’ lungs or stomachs.[6]
  • Bottlenose dolphins are the most common and well-known type of dolphin.[10]
  • Unlike most wild animals, wild dolphins have been known to play with humans, especially children
  • While most wild animals avoid contact with humans, wild dolphins are known to play and associate with humans, especially children.[2]
  • Dolphins have names for each other and call out to each other specifically.[4]
  • Pink dolphins, called “botos,” are actually albino dolphins. They typically live in Brazil, but have been seen in the Gulf of Mexico.[4]
  • Dolphins can kill sharks with their noses. They may even circle around a shark to coordinate an attack.[3]
  • Dolphins are one of the few animals that can use tools. They use broken sea sponges to protect their noses while they forage for food.[8]
  • Dolphins have been known to work with both whales and humans to hunt for food.[8]
  • Dolphins don’t have a sense of smell, but they do have a sense of taste and, like humans, can distinguish between sweet, sour, bitter, and salty tastes.[7]
  • The term “dolphin” is from the Greek delphis, which is related to delphys (such as the Delphic Oracle), meaning “womb.”[6]
  • Dolphins, porpoises, and whales are all mammals called cetaceans, which is from the Greek word meaning “sea monster.”[8]
  • Dolphins are divided into two distinct family groups. The larger, more common group is the Delphinidae family, which are salt-water dolphins. The smaller group is the Platanistidae family, which are freshwater dolphins.[3]
  • The Killer Whale is the largest species of the dolphin family
  • The killer whale is the largest dolphin (true whales don’t have teeth but sift their prey through plates of baleen). The smallest dolphin is the Hector’s or Maui’s dolphin, of which only 150 are left today.[3]
  • Dolphins and porpoises are related, but they are not the same. Porpoises have smaller heads and shorter snouts than dolphins. They also have spade-shaped teeth, while dolphins have cone-shaped teeth.[6]
  • Dolphins can swim up to 30 miles (48.3 km) per hour.[4]
  • Some dolphins can dive as deep as 1,500 feet (457.5 m), but they usually stay within 200 to 250 feet (61 to 76.3 m) of the water’s surface.[4]
References

1"11 Facts about Dolphin Hunts." Do Something. Accessed: April 11, 2017.

2Bearzi, Maddalena and Craig B. Stanford. Beautiful Minds: The Parallel Lives of Great Apes and Dolphins. Cambridge, MA: Harvard University Press, 2008.

3Catton, Chris. Dolphins. New York, NY: St. Martin’s Press, 1995.

4Claybourne, Anna. Dolphins (Living in the Wild: Sea Mammals). Chicago, IL: Heinemann Library, 2013.

5"Do Dolphins Have Belly Buttons?" Whale Facts. 2017. Accessed: April 11, 2017.

6Donoghue, Michael and Annie Wheeler. Save the Dolphins. New York, NY: Sheridan House, Inc., 1990.

7Frohoff, Toni and Brenda Peterson. Between Species: Celebrating the Dolphin-Human Bond. San Franciso, CA: Sierra Club Books, 2003.

8Gagne, Tammy. The Smartest Animals: Dolphins. North Mankato, MN: ABDO Publishing Company, 2014.

9Querna, Betsy. “Dolphins Recognize, Admire Themselves in Mirrors, Study Finds.” National Geographic. May 2, 2001. Accessed: June 26, 2016.

10Reynolds III, John E, Randall S. Wells, and Samantha D. Eide. The Bottlenose Dolphin: Biology and Conservation. Tampa, FL: University Press of Florida, 2000.

11Saul, Heather. "Two-Headed Dolphin Found on Turkey Beach." Independent. August 12, 2014. Accessed: April 11, 2016.

12Secret Language of Dolphins.” National Geographic Kids. 2016. Accessed: June 26, 2016.

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