What kind of animal is the spotted dolphin? We will explain its characteristics, ecology, and habitat. The spotted dolphin is not well known because there are very few of them. Although the population is now very stable, bycatch was a problem in the past, and it was suggested that it may become extinct.
What is a Spotted Dolphin? Basic Stats
The Pantropical Spotted Dolphin is a dolphin that belongs to the Cetacean order, Odontoceti suborder, Delphinidae family, and Stenella genus. Its English name is Pantropical Spotted Dolphin, and its scientific name is Stenella attenuata. The kanji for Spotted Dolphin is Madaraumiton. The list of information is as follows.
| Japanese（和名） | マダライルカ |
| English（英名） | Pantropical Spotted Dolphin |
| scientific name(学名) | Stenella attenuata |
| classification（分類） | Mammalia、Cetartiodactyla、 Delphinidae、Stenella 哺乳綱、クジラ目、ハクジラ亜目、スジイルカ属 |
| IUCN Status(保全状況) | LEAST CONCERN |
| Length（体長） | 80-90cm |
| Weight（体重） | 120kg |
About classification
There are three subspecies of spotted dolphins. They are classified according to the populations that live in the eastern Pacific, Hawaii, and Mexico. Two of the three subspecies (Stenella attenuata subspecies A and Stenella attenuata subspecies B) do not have official names.
- Stenella attenuata subspecies A
- Stenella attenuata subspecies B
- Stenella attenuata graffmani
Taxonomy of Spotted Dolphins
- 界（Kingdom）: 動物界 (Animalia)
- 門（Phylum）: 脊索動物門 (Chordata)
- 綱（Class）: 哺乳綱 (Mammalia)
- 目（Order）: 鯨偶蹄目 / 鯨目 (Cetacea)
- 亜目（Suborder）: 歯鯨亜目 (Odontoceti)
- 科（Family）: ハクジラ科 (Delphinidae)
- 属（Genus）: マダライルカ属 (Stenella)
- 種（Species）:
- コビレマダライルカ (Stenella attenuata)
- ミナミマダライルカ (Stenella longirostris)
※日本周辺で見られるのは主に コビレマダライルカ（Stenella attenuata）
Habitat
Spotted dolphins live in temperate, subtropical and tropical waters around the world.
- Main Habitat
Tropical to subtropical Pacific, Atlantic, and Indian Oceans
In Japanese waters, they can be found in the waters around Okinawa and south of Kyushu.
Open Ocean and Coastal Waters
They often live in schools in the open ocean.
In coastal areas, they may gather in areas with abundant fish.
- Habitat Characteristics
Water Temperature: Prefers warm waters (approximately 20-30°C).
Depth: Found in a wide range of waters, from deep open ocean waters to mid-depths along the coast.
School Life: Forms large schools of dozens to hundreds of individuals, and moves in pursuit of feeding grounds.
Migration: They are migratory, moving according to the season and areas with abundant food.
- Points of Interest
They do not enter rivers; they are entirely marine.
They prefer the open ocean over shallow waters, swimming at high speeds to chase fish and squid.
They often move in schools, following ocean currents and tidal currents.
What are its characteristics? What kind of creature is it?
Spotted dolphins have a long, thin beak. They have a high, curved dorsal fin and pointed pectoral fins. Their back is dark gray and their underside is grayish white. Spotted dolphins are found in temperate, subtropical and tropical waters around the world, and their total population is said to be over 3 million. This makes them the second most common species after bottlenose dolphins. They prefer warm places, as they are most likely to live in warm waters above 25°C.
- Physical Characteristics
Body Color: Gray to blue-gray with black and white spots (especially noticeable in adults)
Body Length and Weight:
Adults measure approximately 2 m in length
Weight: Approximately 100-150 kg
Dorsal Fin: Triangular, slightly curved
Snout: Long, pointed
Body Shape: Slender and streamlined, well-suited for fast swimming
- Behavior and Personality
School Life
Often swims in schools of dozens to hundreds of individuals
Communicates with others through calls and clicking sounds
Playful and agile
Often surfs, jumps, and splashes with their tail fins
Swims fast in the open ocean in pursuit of prey
Highly Curious
May approach boats and humans
- Ecological Characteristics
Diet: Small fish, squid, and crustaceans
Reproduction: Gives birth to one calf at a time
Gestation Period: Approximately 10-12 months
Raising is primarily done by the mother, with cooperation from the group.
Adaptations: Because they live in the warm waters of the open ocean, they are more sensitive to changes in water temperature than dolphins that live in colder climates.
What is their personality like?
Spotted dolphins are very social animals that value discipline. They are usually seen in groups, but they often act alone. Spotted dolphins are very active and make large jumps out of the water. They are also known to “play” by jumping over the bow waves made by ships.
- Sociable
Live in groups of dozens to hundreds of individuals.
Communicate with group members through calls and clicks.
Cooperative behavior has been observed between mothers and their young, as well as the entire group.
- Inquisitive
They often approach boats and tourists.
They often play in response to objects and waves at sea.
- Playful and Active
Jump on the water surface and splash with their tails.
They chase each other in groups and engage in surf-like behavior.
Young animals learn hunting and social skills through play.
- They can also be timid.
They are wary of predators and large ships, and will quickly flee.
When they sense danger, the group may change direction all at once.
What is their ecology like?
Spotted dolphins live by eating fish, crustaceans, invertebrates, etc. Their lifespan is about 40 years, with females reaching sexual maturity at 10 and males at 12.
- Habitat
Live in open ocean and coastal areas
Distributed in tropical to subtropical Pacific, Indian, and Atlantic Oceans
Appears in the waters around Japan, from Okinawa to southern Kyushu
Water Temperature: Prefers warm waters of approximately 20-30°C
Depth: Lives in a wide range of waters, from deep open ocean waters to mid-depths along the coast
School Life: Forms schools of tens to hundreds of individuals and moves in search of areas with abundant food
- Diet
Mainly small fish, squid, and crustaceans
Prey Method: Swims at high speed to chase fish, sometimes working together as a school to hunt
- Reproduction and Rearing
Gestation Period: Approximately 10-12 months
Birth: One baby at a time
Rearing: Mother-centered, with some cooperation within the group
Chubby learn hunting and social skills through play
- Society & Behavior
Living in groups: Highly social, they communicate with each other through calls and clicking sounds.
Swimming Behavior: Active, including jumping, splashing with their tail fins, and surfing.
Mobility: They migrate according to the season and food resources.
- Adaptability
Streamlined, slender body → Fast, adaptable to life in the open ocean.
Specialized for life in warm waters, they do not venture into colder regions.
They have developed hunting and communication skills in groups.
Do they have any natural predators?
The greatest threat to spotted dolphins is the killer whale.
About baby spotted dolphins
Baby spotted dolphins (Stenella attenuata / Stenella longirostris) are smaller than adult dolphins and have distinctive behavior and ecology.
- Physical Characteristics
Body Length: Approximately 70-90 cm at birth
Weight: Approximately 10-15 kg
Body Color: Juveniles are gray or blue-gray, developing spotted patterns as they mature
Dorsal Fin/Snout: Same shape as adults, but smaller
- Behavior/Personality
Dependent on Mother
For the first few months of life, they swim alongside their mother, protecting them from food and danger.
Playful
Jumping on the surface of the water and splashing with their tail fin and body
Playing games with their packmates
Learning Behavior
They learn how to catch food and social skills by watching the behavior of their mother and pack.
- Biological Features
Diet: Breastfed for the first few months
Weaning: Begins eating fish, squid, etc. after a few months to a year
Growth: Reaches near adult size within 1-2 years and is able to participate in pack activities
Dangers: Juveniles are sensitive to predators, ships, and food shortages, making them at high risk.
Are spotted dolphins an endangered species?
Spotted dolphins are not an endangered species overall. However, in the 1900s, there were concerns that they might become extinct. This was because they were caught in large numbers as bycatch in fishing operations. In the 1980s, conservation efforts became more active and their population rapidly increased.
- International Union for Conservation of Nature (IUCN) Assessment
Short-finned Spotted Dolphin (Stenella attenuata)
Classified as “Least Concern” on the IUCN Red List
Relatively stable population and widespread distribution
Southern Spotted Dolphin (Stenella longirostris)
Overall, classified as “Least Concern”
Some local populations may be affected by fishing and marine pollution
- Reasons for Not Being Endangered
Distributed over a wide area of tropical and subtropical waters
Living in groups, with a relatively stable reproductive rate
Natural predators are limited to killer whales and large sharks
- Caution
Damage to Fisheries: Populations may decline due to purse seine nets and bycatch
Environmental Change: Marine pollution and climate change may affect food resources and habitat
Can spotted dolphins be kept as pets?
Spotted dolphins are too large for ordinary people to keep as pets. If you want to find one, we recommend visiting an aquarium or other place to view them and getting a guide or escort at an event.
- Legal and Conservation Issues
Spotted dolphins are internationally protected marine mammals.
Capturing and selling wild specimens is prohibited in most countries.
Even in Japan, keeping wild dolphins as pets is illegal.
Only aquariums and research facilities with special permission can keep them.
- Ecological and Environmental Issues
Large ocean space required: They form schools in the open ocean and hunt for food while migrating.
Highly social: Dolphins live in groups, and keeping them alone can be stressful.
Unique diet: They require large amounts of small fish, squid, and crustaceans, and they must learn predatory behavior.
Water temperature management is difficult: They are adapted to tropical and subtropical water temperatures (20-30°C).
- Aquarium Keeping
Only kept in aquariums worldwide.
Even in Japan, there are few examples of captivity, requiring large tanks, specialized staff, and veterinarians.
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