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Dolphins: The Most Loved Marine Mammal In The World

Updated on May 9, 2014

Dolphin Smile

Dolphin from photobucket by hikari_miyako
Dolphin from photobucket by hikari_miyako | Source

The Dolphin

One of the most adored marine mammals is the dolphin. They are related to porpoises and whales and can vary in size from 4 feet long to 30 feet long and weigh as little as 90 pounds or as much as 10 tones. It is believed that the dolphin evolved over ten million years ago and they are by far one of the most intelligent and playful animals which has earned them a special place in human culture.

Dolphins have a body that is perfectly sculptured for swimming. It is streamlined and smooth and ended with a tail fin, or fluke, that is used for propelling. Their pectoral fins offer directional control and some species are even equipped with a dorsal fin that provides stability.

Their head contains a round organ, called a melon that they use for echolocation and in many species, their elongated jaw gives them a happy, smiling appearance. Certain dolphins can house up to an unbelievable

Swimming with Dolphins


Most dolphin species have fabulous eyesight, inside and outside of the water. Additionally, they have the ability to hear 10 times more frequencies than a human being. They are equipped with two small ear openings but it is believed that they use their lower jaw to hear underwater as it works as a middle ear. Interestingly, their teeth work like an antenna, receiving sound and pinpointing location.

Dolphins have a very strong sense of touch and nerve endings that are packed in the skin, primarily around the genital area, snout and pectoral area. It is believed that they have no sense of smell but they can taste and have a preference for the flavor of certain fish over others.

Although most dolphin species do not have any hair, they are equipped with hair type follicles that serve as a sensory function.

Hourglass Dolphins

Photo of Hourglass Dolphins taken from the Greenpeace ship Esperanza by
Photo of Hourglass Dolphins taken from the Greenpeace ship Esperanza by | Source

Training Dolphins

Social Behavior

Dolphins are extremely social marine mammals often living in pods of 10 to 15 and then forming groups of over 1000. They can make ultrasonic noises for echolocation purposes and use whistle, clicks and other vocalizations for communication.

Dolphins often establish strong bonds with other animals and humans. They will stay with their own if one is injured and help them to the surface to breathe and they have even been reported as protecting surfers and swimmers from sharks by either circling the human to form a protective wall or charging at the shark to chase it away.

Dolphins can be aggressive toward each other though and the older the dolphin, the more scars it is likely to have on its body. Most often, disputes are between the males competing for a female. Some species even engage in infanticide, killing off the young for an unknown reason.

Dolphin Air Ring

Dolphins blowing air rings at Seaworld Florida taken by
Dolphins blowing air rings at Seaworld Florida taken by | Source

Complex Play

Dolphins are extremely playful animals and will often create bubble rings by either puffing air in the water, allowing it to form a ring as it rises to the surface or by swimming in circles and then injecting air in the current already formed. They also love to bite at the bubble ring so that it bursts into many other bubbles. Dolphins are known for riding in both natural waves or those introduced by a moving boat.

Dolphins Reacting To A Mirror

Problem Solving

It is believed that dolphins can not only recognize themselves in mirrors but they can discriminate between numbers too. However, others believe that the discrimination is due to their genius talent of mimicry. They are thought to have the ability to think abstractly, reason, solve problems, learn quickly, learn from experience and comprehend complex ideas. Many researchers are ranking dolphin intelligence to the elephant intelligence level.


Since a dolphin has to come to the surface to breathe, only one hemisphere of its brain is in a slow-wave sleep state at a time allowing them to maintain consciousness to not only breathe but also watch for predators. Dolphins that live among strong currents and floating debris have to swim continuously in order for them to avoid injury, so these species only sleep in short bursts that last generally less than one minute long.

Feeding Dolphin

Feeding Dolphin by
Feeding Dolphin by | Source


Squid and fish are the most common food choices for most dolphins. A pod will often use a herding method where they will squeeze a school of their selected fish into what is called, a bait ball. Individual dolphins then take turns barreling through the ball of fish and feeding on the stunned ones. Another method is called corralling, where the dolphin chases fish into shallow water so that it can easily catch them. Other species will whack the fish out of the water to stun them and a few have been reported coming onto the beach to capture a sea lion.


Copulation between dolphins occurs belly to belly. The sexual act is quite brief but many species engage in a long amount of foreplay. Depending on the species, the gestation period can be anywhere from 11 to 17 months. Yong adults become sexually active usually long before they even reach sexual maturity. Dolphins will often have sex even without reproduction reasons and even engage in homosexual behavior. Occasionally, they will also behave sexually towards humans and other animals.

Man: Threat to Dolphin.


Some dolphin species are critically endangered and others are extinct. Pesticides, plastics and other pollutants are environmental threats as well as common collisions with boats. Fishing methods used for tuna unintentionally kill many dolphins and in some countries, they are killed in drive hunts. Additionally, loud underwater noises can damage their hearing or cause decompression sickness from them surfacing too fast to escape the noise. Man is the greatest threat to dolphins.


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