Pink dolphin brains are 40% larger than human brains


We must protect the web of life and care about the other living species we share this planet with. Pygmy tarsiers eat and host insects we’ve seen in our homes — bugs, spiders, lizards, bed bugs, lice, fleas, roundworms, and tapeworms. The vaquitas are preyed upon by large sharks and killer whales, which keeps them away from us. But while there were only 10 vaquitas left last year, their numbers have continued to fall today. A tiger in the wild indicates that the forest it lives in is healthy and diverse. There are currently 3,900 tigers in the wild worldwide and more than twice as many (8,000) in captivity. By protecting the web of life, we are building a kinder world for everyone.

There are pink dolphins (Inia araguaiaensis) in the Amazon River in South America. They are very intelligent, with a 40 percent higher brain capacity than a human brain.

They inhabit the Amazon, the largest river in the world in terms of freshwater volume. This river crosses Bolivia, Brazil, Colombia, Ecuador, Peru and Venezuela.

The pink dolphin is also called the Amazon river dolphin, the pink river dolphin, boto cor-de rosa, (pink river dolphin) or botos, which we will call them in this article. They weren’t always pink. They are gray at birth, then turn pink with age.

Their degree of pink varies. Some have only pink speckles, while others are all pink. Pinkness is stimulated by their placement in the capillaries, nutrition, sun exposure and emotions. Pink male dolphins turn a brighter pink when excited, especially during the mating season. Females are most attracted to the pink dolphins. Gray dolphins roughly attack their pink counterparts, resulting in scar tissue that adds more pink. Sometimes the male boto has a “gift” in his mouth for a female.

Swimming in the forest

Reproduction occurs in the rainy season, when the Amazon rainforest is flooded with water, allowing male botos to leave the flooded rivers and swim for miles among the flooded forest trees.

The Amazon wetlands system was granted international protected status in 2018 due to the role it plays in dolphin breeding. The males reach females who live in lakes. The habitat of the boto is both the forest and the river. When the rainy season ebbs, the males return to the Amazon River.

Mother botos are pregnant for 13 months, they feed their young for two years and reproduce every 3-5 years. Botos have a lifespan of 30 years.

Myths of the river dolphin

Some locals still believe in ancient myths that botos are semi-divine and magical. Other boto myths include:

  1. Morphing. According to Amazon folklore, botos turn into handsome men dressed in white, called “boto encantado”, or “enchanted”. They seduce and impregnate women and return to the river at dawn. In Sy Montgomery’s book,

Journey of the Pink Dolphins: An Amazon Quest, a man tells of his cousin’s wife who was fooled by a boto disguised as her husband. The woman became pregnant and gave birth to the child of the boto.

  1. kidnapping. You should not swim alone, because a boto can kidnap you and take you to Encante, a magical underwater city.

  2. Avoid direct eye contact with a boto. Otherwise you will have nightmares and evil visions for a lifetime.

  3. Rainforest mystics are thought to have learned the healing art of botos.

  4. Harming Botos and eating brings bad luck.

Meg Symington of the World Wildlife Foundation said myths “played a role in the stability of (boto) populations.”

Facts about botos

Botos are sweet, docile and shy, but are curious about people and will play with local children. However, botos can bite like piranhas, so one has to be careful and keep a respectful distance.

As the largest freshwater dolphin, the boto can grow 9 feet and weigh 400 pounds. It is the best dolphin swimmer. Because his vertebrae are not connected to each other, he makes 180-degree turns even in shallow waters. Because his neck vertebrae are detached in the same way, he can look back 90 degrees as he swims forward. He swims on his back for a better view, as his plump cheeks block the view downwards when he swims on his stomach. Sometimes botos rest on the seabed, balancing on its two side fins and tail.

The boto navigates the polluted Amazon by echolocation. It can locate invisible, distant objects and capture prey even without eyesight. The large bump on top of the boto’s head is a “lens” that allows focus on echolocation. To hear it, go here at 1:14.


The IUCN ranked the Inia geoffresis (Amazon River Dolphin) as endangered in 2018. However, the boto is a subspecies of Inia geoffresis and is referred to as Inia araguaiaensis. Until now, botos have not been fully counted, but estimates range from a few dozen to several thousand.

Biologist Susana Caballero, Universidad de los Andes, Bogota, studied boto genetics using fat samples. She determined that there is uncertainty about boto populations and that it is possible for a single species to have four separate subspecies. Because they are endangered, unique dolphin species could become extinct before science even knows about them.

Caballero further noted that if one assumes that a dolphin species has 10,000 individuals, but there are four subspecies, that would mean 2,500 individuals per subspecies. Caballero concluded that the boto is critically endangered.

In Brazil alone, botos’ population decline is due to fishermen’s gillnets. In less than 50 years, Brazil’s boto population could decline by at least 95 percent.


Other threats causing the heavy decline of botos include:

  1. An increase in hunting botos with the lifting of the ban on hunting catfish (Piracatinga) in 2o14. In January 2020, boto fisheries rose due to its fatty blubber, used by anglers to lure catfish, commanding a high price in city markets.

  2. People riding in motorized boats sometimes collided with botos, causing their death or injury.

  3. The increasing pollution of the boto’s habitats, both in the water and in the forest, is affecting their health and life.

  4. Mercury used to mine gold results in land and water deposits of mercury and methylmercury (the most toxic form). They inhabit both the forest floor and the bottom of the Amazon River, where bottom feeders such as catfish eat them. Tests have shown that catfish predators, including botos, have high, unsafe levels of mercury. Eighty percent of South America’s mercury emissions come from the Amazon.

  5. Deforestation destroys forests, another boto habitat. The land is used for grazing animals and fallen trees are used for construction, production and fuel. Deforestation affects the food chain.

  6. Studies show that dams fragment and isolate boto populations, degrading their downstream habitat.

Finding Botos

How far do botos swim? Fernando Trujillo, dolphin expert, Omacha Foundation, captures, measures and tags bots to track them. He found that male botos travel up and down the river, congregating at river crossings where food is plentiful.

Trujillo learned that males travel long distances along the river with every change of season, while females stay in one place to care for their calves.

However, human interference has taken its toll and the boto’s food supply is declining. As a result, two botos will fight over one fish. You can see this, here at 2:18.

Wildlife presenter Steve Backshall spent months on the Amazon before finally seeing botos in the wild for two minutes. He fed them and the botos went for it. Backshall said their intelligence probably helped them get the food they were given, rather than just relying on what they catch. Go here to see pink dolphins in the wild.

What is being done to them?

Trujillo’s discovery of boto hotspots informs him where to focus conservation efforts, rather than trying to protect the entire river.

Caballero said more money is needed to further study the genetics of botos, including alleles (which indicate small differences in the same gene and their DNA sequence. This reveals an individual’s unique physical characteristics).

A South American river dolphin action plan dates from 2010 to 2020, so an update on the action plan’s progress is needed with updated targets and methodologies.

What is necessary

More research on the boto is needed, especially genetic studies to further guide an updated identification of the boto species and their counting. To date, the exact number of botos is unknown.

The ban on piratena fishing ended in January 2020, but scientists are calling for its extension. Otherwise, fishermen will continue to kill botos and use their fat as bait for catfish.

Why are botos ecologically important?

The boto has a special ecological niche. Their biology and ecology are highly attuned to seasonal variation and changing water levels. This makes them important predators of a wide range of fish species in the river and forest when it floods, keeping prey populations in check.

The only known predator of botos today is humans. Botos do not travel in large groups (typical of animals eaten by carnivores). They only hunt during the high water season and sometimes 5 to 35 botos gather to catch prey.

The intrinsic value of botos should be considered. Their intelligence and superior brain power over human brains can help us see learning opportunities that are still unknown. Of course, this can’t happen if they go extinct, so the priority is to save their lives.

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