We will explain the characteristics, ecology, and habitat of the Amazon river dolphin. It is the largest living dolphin species and lives primarily in South America. Unfortunately, it is listed as an endangered species. We will explain the detailed ecology and characteristics.
What is the Amazon river dolphin? About basic status
The Amazon river dolphin is a cetacean classified in the mammalian class Artiodactyla (Cetacean artiodactyla) and the Amazonian river dolphin family Amazon River dolphin genus. The scientific name is Inia geoffrensis. The body length is 2.8m and the weight is 100-160kg.
| Japanese（和名） | アマゾンカワイルカ |
| English（英名） | Amazon river dolphin |
| scientific name(学名) | Inia geoffrensis |
| classification（分類） | Mammalia、 Artiodactyla/Cetartiodactyla、Iniidae、Inia 哺乳綱、偶蹄目/鯨偶蹄目、アマゾンカワイルカ科、アマゾンカワイルカ属 |
| IUCN Status(保全状況) | ENDANGERED |
| Length（体長） | 2.8m |
| Weight（体重） | 100 – 160kg |
About classification
The Amazon river dolphin was originally classified as a member of the family Pelfinidae, but it has now been divided into the Amazonidae family. We have compiled a list of similar types below.
| Name (名前) | Scientific Name （学名） | Habit （生息地） |
| Amazon river dolphin | Inia geoffrensis geoffrensis | Ecuador, Brazil, and Peru エクアドル、ブラジル、ペルー |
| Bolivian river dolphin | Inia geoffrensis boliviensis d’Orbigny | Bolivia ボリビア |
| Orinoco river dolphin | Inia geoffrensis humboldtiana Pilleri & Gihr | Colombia and Venezuela コロンビア、ベネズエラ |
| Araguaian boto | Inia araguaiaensis Hrbek | Tocantins-Araguaia River Basin in the Amazon River Basin アマゾン川水域のトカンチンス・アラグアイア川流域 |
About habitat
As mentioned above, Amazon river dolphins live throughout South America.
- Main Habitat
Amazon River Basin: The Amazon River and its tributaries flow through countries such as Brazil, Peru, Colombia, Bolivia, Ecuador, and Venezuela.
Orinoco River Basin: Small populations exist in the Orinoco River, particularly in Colombia and Venezuela.
Freshwater Rivers and Lakes: They migrate seasonally as river water levels fluctuate, and during flood season, they may enter surrounding wetlands or temporary lakes.
- Habitat Characteristics
They specialize in freshwater and do not inhabit saltwater.
They prefer rivers with relatively calm depths and currents and abundant fish.
They can survive in relatively warm waters (approximately 25-30°C), even in murky waters.
- Distribution
Amazon river dolphins are widely distributed throughout rivers, from upstream to downstream, but populations are declining in some areas due to human activity and water pollution.
Due to their widespread migration during flood season, accurate population counts can be difficult to ascertain.
feature is? What kind of creature is it?
The Amazon river dolphin is the largest species of river dolphin. Its most distinctive feature is its snout and pink body color. Mainly bright pink, but also dark brown, cream, etc. The front teeth are sharp and pointed, and are used for catching fish rather than chewing food. Although their eyes are extremely small, their eyesight is very high. The pectoral fins are large relative to the body length and curve backwards. They usually travel alone or in pairs.
- Appearance and Physical Characteristics
Body Color: Adults range from pale pink to deep pink, with the color intensity varying between individuals. Young individuals are grayish, becoming more pink as they grow.
Body Length and Weight:
Body Length: Males approximately 2.5-2.8m, females approximately 2.3-2.5m
Weight: Males approximately 150kg, females approximately 100kg
Head: The forehead is rounded and the mouth is elongated and “beak-like,” making it easy to catch fish.
Dorsal Fin: There is only one small, rounded dorsal fin, not as large as that of an oceanic dolphin.
Fins and Tail: The pectoral fins are large and broad compared to the width of the body, and the tail fin is horizontally spread.
- Behavior and Ecology
Diet: Carnivorous, primarily eating fish, but also eating shrimp and crustaceans.
Intelligence: Even among dolphins, they are highly intelligent, exhibiting curious and playful behavior.
Sociality: They tend to live alone or in small groups. They rarely form large schools.
Aquatic Behavior: They often breathe near the surface and sometimes jump or slap the water with their tail fins.
- Special Characteristics
Color Change: When excited or active, their color may become a deeper pink due to increased blood flow.
Flexible Neck: Their neck bones (cervical vertebrae) move freely, allowing them to shake their heads from side to side. This is a characteristic not commonly seen in sea dolphins.
What is the ecology like?
Amazon river dolphins live by eating fish and squid that live in rivers. Breeding is seasonal, with birth occurring from May to June. The gestation period is estimated to be about 11 months, and lactation takes about a year. Dolphins become independent within two to three years. The average lifespan of Amazon river dolphins in the wild is unknown. Their lifespan in captivity is 10 to 30 years.
- Diet (What they eat)
They are freshwater carnivores, primarily feeding on fish.
They use their beaks to search for fish on the riverbed or among aquatic plants.
They occasionally eat shrimp, crustaceans, and small frogs.
They are nocturnal, with many individuals actively hunting at night or in the evening.
- Reproduction and Growth
Reproduction: Viviparous (they carry their young inside the womb)
Gestation Period: Approximately 11-12 months
Birth: Usually one pup
Child Development: They stay with their mother immediately after birth, and nursing continues for several months.
Sexual Maturity: Females reach maturity at 5-6 years, males at 7-10 years
Lifespan: Approximately 30-35 years in the wild
- Behavior and Sociality
They live alone or in small groups. They typically live in groups of a few to 10 individuals.
They are highly intelligent and curious, and may approach boats.
Communication: They communicate with each other through clicking and calls.
- Movement/Habitat Use
Seasonal Movement: Their range changes between the rainy and dry seasons.
Rainy Season: When rivers flood, they move to nearby wetlands or temporary lakes.
Dry Season: As water levels drop, they return to the main river or deeper waters.
Territory: While some individuals stay in a particular location for long periods of time, many individuals also move in search of food.
- Natural Enemies/Threats
They have few natural predators, with large fish and jaguars occasionally attacking young ones.
Human Impacts: The main threats are water pollution, dam construction, and bycatch in fishing.
About Baby Amazon River Dolphins
This article provides a detailed explanation of baby Amazon river dolphins, covering their appearance, growth, behavior, and mother-offspring relationships.
- Appearance and Physical Characteristics
Body Color: Immediately after birth, they are gray or light gray, with pink not yet noticeable.
Body Length and Weight:
Body Length: Approximately 80-100cm
Weight: Approximately 10kg
Beak: Short, lengthens as they grow.
Fins and Tail: Small and soft, but gradually acquire the same shape as their mother.
- Growth and Development
Nursing Period: Nursing continues for several months. Breast milk is highly nutritious and provides the energy needed for growth.
Weaning: Weaning usually begins practicing fishing between 6 months and 1 year, but becomes fully independent around 2-3 years of age.
Sexual Maturity: Males reach sexual maturity between 7-10 years of age, and females between 5-6 years of age.
- Behavior and Mother-Child Relationship
Cubs always accompany their mothers, often clinging to their backs or sides in the water.
Mothers protect their young while teaching them how to catch food and swim.
Cubs also play with each other, making this an important time for them to learn social skills and motor skills.
- Threats and Survival
Cubs are more vulnerable to predators than adults, and can be attacked by jaguars, large fish, and anacondas.
Cubs are vulnerable to predators if isolated due to changes in water levels or the environment, making survival difficult. Therefore, maternal protection is extremely important.
Is the Amazon river dolphin an endangered species?
Unfortunately, the Amazon river dolphin is listed as an endangered species (Red List) according to information. It is also listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), and international trade is strictly restricted. Due to their pink color and larger body size than humans, both males and females are easy targets in daily life. Many dolphin species are in a critical situation. Dam construction is also a nuisance.
Overfishing by local fishermen
Amazon river dolphins are overfished by local fishermen, and are removed for consumption as meat or because they interfere with fishing operations. Despite Brazil banning the killing of Amazon river dolphins, killings continue.
Tropical rainforest pollution and destruction
The biggest problem is due to water pollution and environmental destruction. As a result, the dolphins’ health is compromised and they live in extremely dangerous conditions. Dumping of mercury and other powerful chemicals into watersheds from industrial mining is harmful to life.
River dolphin world declaration
In 2024, the Global River Dolphin Declaration was adopted. We aim to reverse the decline in river dolphin populations around the world. As of early 2024, 11 of the 14 countries that keep river dolphins have signed the declaration.
Can Amazon river dolphins be kept in captivity?
Unfortunately, it is listed as an endangered species. Furthermore, international trade is severely restricted by CITES, making it extremely difficult to keep Amazon river dolphins in captivity.
- Ecological Reasons
Requires a Wide Range of Movement: Their range changes between the rainy and dry seasons, and in the wild, they can travel more than tens of kilometers. Small aquariums can be very stressful for them.
Special Diet: They primarily eat freshwater fish, but it is difficult to secure wild fish. It is also difficult to provide sufficient nutrition with artificial feed.
Sociality: Because they value mother-child relationships and small group behavior, they experience psychological stress when kept alone or in unnatural environments.
- Laws and Regulations
Amazon river dolphins are listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), and international trade is restricted.
In many South American countries, wild capture and captivity are generally prohibited.
Even in Japan, due to environmental conservation and invasive species regulations, it is impossible for individuals to keep them as pets.
- Conditions in Captivity
Freshwater dolphins are extremely rare worldwide. They are occasionally kept in captivity at some research facilities and zoos in Brazil for research and conservation purposes.
Keeping them requires large aquariums, a supply of freshwater, fish stocking, specialized veterinarians and staff, making them very expensive.
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