40 Interesting Facts About Dolphins

1. Dolphins are aquatic mammals that belong to toothed whales. They are among a few animals present in oceans and rivers.
2. There are nearly 40 species of dolphins. Most of these live in oceans (such as common dolphins, bottlenose dolphins, etc.), while few species have adapted to live in freshwater (Amazon river dolphins, Indus river dolphins, etc.).
3. Six species of dolphins are known as whales. These include killer whales, pilot whales, false killer whales, etc.
4. The largest dolphin is the orca or killer whale, which can grow up to 30 feet long. Maui dolphin is the smallest species with a length of up to 5 feet.
5. Dolphins mostly live in temperate and tropical waters. However, they are present in every ocean and sea except the Aral Sea and the Caspian Sea.
6. Most vertebrates have five tastes, but dolphins and whales can only taste salty flavors. They lost taste sensations for all flavors except salt around 53 million years ago. (Source)
7. Oceanic dolphins have sharp vision both in and out of water. They can see forward, backward, and sideways thanks to their 180^O visual range. But river dolphins have very weak or no vision (Indus dolphins are blind).
8. Both eyes of a dolphin can move independently of each other. It enables them to see in various directions simultaneously.
9. Despite the absence of external ears, dolphins have an excellent sense of hearing for low-frequency and high-frequency sound waves. They can hear via inner ears, connected from outside through tiny holes on each side of the head.
10. The sense of smell is very weak or absent in dolphins. They compensate this by using their senses of hearing, taste, and sight.
11. Dolphins communicate by producing several sounds, including clicks, whistles, and squeaks. They use a secret language for communication, currently unknown for humans. These mammals also use body postures to convey message. (Source)
12. The first-ever hybrid dolphin was found in 2018. It was a hybrid of a rough-tooth dolphin and a melon-headed whale. Its discovery location was off the coast of Hawaii. (Source)
13. Dolphin drive hunt is a historical method for hunting dolphins. It is still popular in Japan, where they hunt numerous dolphins by driving them into a shallow bay. (Source)
14. According to estimates, the ancestor of dolphins was a four-legged land mammal. Modern-day dolphins initially appeared on earth around 5 million years ago.
15. The closest living relative of dolphins is hippopotamus. However, their common ancestor was a land-dwelling mammal, and cetaceans (dolphins and whales) independently adopted various traits suitable to the marine life. (Source)
16. Dolphins are very smart and intelligent. They have the second-largest brain-to-body ratio after humans. These mammals have demonstrated their intelligence through playful behavior, complex communication, self-awareness, naming each other, social learning, tool use, and other fascinating traits. (Source)
17. Dolphins are social animals that form groups of 2 to 30 individuals, known as pods. Several pods can unite in areas with an abundance of food to establish superpods. There can be more than 1,000 dolphins in a superpod.
18. Dolphins help injured or weak members of their groups. In 2013, a group of long-beaked common dolphins was seen helping an injured female dolphin. This effort continued until the female dolphin drowned. (Source)
19. Pregnancies in female dolphins last for 10 to 18 months in various species. Unlike most other mammals, calves are born tail first, which protects them from drowning. Dolphins give birth to a single calf every 1 to 6 years, and babies remain with their mothers for 5 to 10 years. Mothers teach them about living traits and social life.
20. All dolphins possess teeth, but their number varies according to species. Risso’s dolphins have a maximum of 14 teeth, while the long-beaked common dolphins can have up to 240 teeth. Most dolphins swallow their food whole, while the teeth are used to grab and grip their prey. (Source)

    

    Long-beaked common dolphins have up to 240 teeth

    
    
21. Like a few other marine animals, dolphins keep one eye and half of their brain open while sleeping. They do so to avoid predators and remain stuck to their group.
22. Dolphins have a remarkable ability to recover from sharp injuries. Experiments have proved that the strong healing ability of these mammals provides resistance to infection and hemorrhage and assists in restoring natural body parts. (Source)
23. According to IUCN Red List, five dolphin species are endangered due to human activities and pollution. These include the Atlantic humpback dolphin, Maui dolphin, Baiji dolphin, Indus River dolphin, and the South Asian River dolphin. (Source)
24. Large sharks and orcas are the only natural predators of dolphins. They face the main threat from human activities such as hunting, by-catch, pollution, underground noise by ships, climate change, and food depletion due to human interference.
25. Dolphins are part of food in a few regions of the world. However, its meat is unhealthy and dangerous for human consumption due to the abundance of mercury. (Source)
26. According to research, swimming with dolphins can treat mild to moderate depression in humans. It is more effective than water therapy. (Source)
27. The lifespan in dolphins is different according to species. Various dolphin species can live from 10 to 60 years.
28. The common dolphin is the fastest marine mammal. It can reach a swimming speed of 60 km/h (37mph). Orca (another dolphin) is the 2^nd fastest marine mammal, with a maximum swimming speed of 56 km/h (34.8mph).
29. On several occasions, dolphins have been seen helping humans and other animals when they are in danger. (Source)
30. Currently, there are more than 3,000 dolphins in captivity inside various zoos, aquariums, and marine parks. The majority of these are bottlenose dolphins, followed by killer whales.
31. Dolphins usually do not migrate. However, seasonal migration is possible in dolphins living in coastal areas.
32. Dolphins are identifiable through their dorsal fins. The edge markings and pigmentation of the dorsal fin are unique in every dolphin. (Source)
33. Dolphins also possess the quality of echolocation, like bats and other marine mammals. It is necessary to see better underwater. They use echolocation with assistance from high-frequency clicks, foreheads, and lower jaw. (Source)
34. The primary food source of dolphins is fish and squid. These carnivorous animals usually find their prey by using echolocation.
35. Dolphins have been seen surfing alongside humpback whales. Both these aquatic mammals play and feed together during this display.
36. Like other mammals, dolphins have lungs instead of gills present in fish. Therefore, they need to take a breath in the air and cannot remain underwater continuously. Dolphins can survive underwater by holding their breath for 10 to 15 minutes. (Source)
37. Dolphin is a Greek word that means “womb.”
38. Dolphins mate any time of the year. Apart from reproduction purposes, recreational sex is also present among these animals.
39. Like primates, female dolphins also have well-developed clitorises. It is therefore estimated that they experience pleasure and orgasm during sex. (Source)
40. Dolphins and porpoises are considered comparable animals due to their similarities. However, there are several notable differences in their body length and the shape of their faces. (Source)