What kind of animal is a blue whale? We will explain its characteristics, ecology, and habitat. It is said to be the largest whale among all whales, and is a marine mammal that takes advantage of its gigantic size to live in the sea. We will introduce its characteristics and habitat.
What is a blue whale? About basic status
Blue whales are marine mammals classified in the order Mammalia, order Artiodactyla, family Finidae. The scientific name is Balaenoptera musculus and the kanji is White Nagasu whale. The total length (body length) is 20 – 26 m, and the weight is 80 – 199 tons. A list of basic information is below. It is the world’s largest marine creature that lives on Earth, and if it grows, it will be extremely large.
| Japanese（和名） | シロナガスクジラ |
| English（英名） | Blue whale |
| scientific name(学名) | Balaenoptera musculus |
| classification（分類） | Mammalia、Artiodactyla/Cetartiodactyla、 Balaenopteridae、Balaenoptera 哺乳綱、偶蹄目、ナガスクジラ科、ナガスクジラ属 |
| IUCN Status(保全状況) | ENDANGERED |
| Length（体長） | 20 – 26m |
| Weight（体重） | 80 – 199t |
About classification
There are 4 subspecies.
- Balaenoptera musculus musculus キタシロナガス Northern blue whale
- Balaenoptera musculus brevicauda ピグミーシロナガス Pygmy blue whale
- Balaenoptera musculus indica Northern Indian Ocean blue whale
- Balaenoptera musculus intermedia ミナミシロナガス Antarctic blue whale
About habitat
Blue whales migrate throughout the world’s oceans.
- Northern Hemisphere
North Pacific: Coast of Alaska, off California, Sea of Japan, Sea of Okhotsk
North Atlantic: Off the coast of Greenland, Iceland, Norway, and the Azores
- Southern Hemisphere
Antarctic Ocean: In summer, they gather around Antarctica to feed on large amounts of krill.
South Atlantic and Indian Ocean: Southern tip of South America, South Africa, southern coast of Australia, etc.
- Tropical and Subtropical Zones
Some individuals overwinter in tropical waters, but their numbers are low, mainly due to a lack of food.
feature is? What kind of creature is it?
The blue whale is the largest living vertebrate species. The body has an elongated shape, and the dorsal side is gray-blue in various colors. The ventral side is slightly brighter in color, and in adults, females are slightly larger than males. It has a streamlined body, long thin pectoral fins, and a thin tail fin that spreads out from the side. Blue whales don’t stay in one place; they move around the world’s oceans. In summer, they appear in the Arctic and Antarctic oceans, where krill are abundant, and in winter, they appear in tropical and subtropical oceans to raise their young in warm waters.
- Physical Characteristics
Size: Total length is 25-30m, sometimes reaching up to 33m.
→ The world’s largest animal
Weight: Approximately 100-200 tons (one of the largest living animals in history)
Body Shape: Long and streamlined. Blue-gray back, pale grayish-white underbelly
Skin: Bluish-gray, sometimes appearing light blue depending on the light
Head: Flat and broad, with a very large head extending from the tip of the mouth to the pectoral fins
Fins:
The pectoral fins are small and slender
The caudal fin is wide and provides excellent propulsive power
- Diet
Food: Mainly krill (small crustaceans)
Feeding Method: Opens its mouth wide, sucks in krill along with seawater, and filters it through its baleen plates before eating.
Daily Intake: May eat approximately 3-4 tons of krill in a single day
- Ecology and Behavior
Migratory: They migrate between the Arctic and Antarctic regions depending on the season.
Calls: They can emit low-frequency sounds that can travel hundreds of kilometers, and they use them for communication and direction-finding.
Lifespan: Average 80-90 years, with some individuals living for over 100 years.
Reproduction:
Gestation Period: Approximately 11 months
At birth, young are approximately 7-8 meters long and weigh 2-3 tons.
- Appearance
They glide across the ocean like a giant submarine.
They are characterized by their backs slightly protruding above the waves to breathe.
Their pectoral and dorsal fins are small compared to their body size, giving them an overall relaxed appearance.
What is your personality like?
Blue whales are docile and do not attack other creatures other than to eat.
- Gentle and Timid
Generally, they are not aggressive toward humans or other creatures.
Despite their large size, they spend most of their time swimming leisurely.
If they sense danger, they often dive and silently escape.
- Sociability
They may be solitary, or they may be found in parent-child pairs or small groups.
In groups, they swim leisurely, maintaining a safe distance from each other.
During breeding season, males may compete for females.
- Curiosity
They may slowly approach human vessels or observers.
However, due to their large size, sudden approaches can mistakenly give them the impression of danger.
- Activity Patterns
They are active both during the day and at night, but they swim long distances at their own pace during migration.
When feeding, they filter out krill with undivided attention.
What is the ecology like?
Blue whales live on a diet of zooplankton called krill and crustaceans. They generally travel alone or in small groups, except during the breeding and rearing seasons. The mode of reproduction is viviparous. They mate in the winter. The gestation period is 12 months. They give birth to one young at a time. Sexual maturity occurs between 8 and 10 years of age. Their lifespan is said to be over 100 years, and some have lived as long as 120 years.
- Migration and Distribution
Blue whales undergo large-scale seasonal migrations.
Summer: They feed on abundant prey such as krill in cold waters such as the Antarctic and Arctic Oceans.
Winter: They migrate to tropical and subtropical waters for breeding and birth.
They often swim alone, but they can also be seen with their calves or in small groups.
- Diet and Feeding Methods
Their primary diet consists of plankton such as krill and small fish.
They filter plankton along with the seawater using their baleen plates (filtering organs unique to baleen whales).
They can eat up to 3-4 tons of krill in a single day.
Most of their feeding occurs in cold waters.
- Reproduction
Breeding season occurs in warmer winter waters.
Gestation period: Approximately 11 months.
Baby: Approximately 7-8 meters in length, weighing approximately 2-3 tons.
Mothers and calves spend several months together, nursing each other.
Males sometimes compete for females during the breeding season.
- Sound and Communication
Low-frequency calls allow for long-distance communication.
Their calls can be heard hundreds of kilometers away, and are used to locate their location during migrations and to communicate with fellow fish.
- Lifestyle
Capable of long dives (average 10-20 minutes, maximum 30 minutes or more).
Swim slowly to search for food.
Come to the surface for short breaths.
- Lifespan and Predators
Lifespan: 80-90 years, sometimes over 100 years.
They have few natural predators, but young fish are sometimes attacked by killer whales and sharks.
Are there any natural enemies?
Blue whales have a natural enemy called killer whales.
About Blue Whale Calves
Blue whale calves (juveniles) are larger than their parents and already possess impressive size from birth. We’ll summarize their characteristics in detail.
- Size at Birth
Total Length: Approximately 7-8 meters
Weight: Approximately 2-3 tons
Compared to humans, they weigh about the same as a small truck.
Even when fully grown, they are still only about half the length of their parents.
- Breastfeeding
Breast milk is very high in fat (approximately 35% fat) and highly nutritious.
They drink approximately 90 liters or more of breast milk per day.
The nursing period lasts approximately 6-7 months, during which they remain constantly with their mother.
During this time, their weight increases rapidly, sometimes reaching more than 90 kg in a single day.
- Behavior and Ecology
Cubs swim close to their mothers and remain safe under their parent’s protection.
They learn breathing and diving techniques from their mothers.
They rarely travel in groups; instead, they primarily live as a mother-calf unit.
During their first long-distance migration, they swim in unison with their mothers.
- Sound and Communication
Young cubs also emit low-frequency calls to communicate with their mothers.
They still have weak vocalizations and often respond to their parents’ calls.
- Growth Rate
They grow to approximately 10-12 meters in length within the first year of life.
They initially feed exclusively on their mother’s milk, but after weaning, they gradually begin to eat krill and other foods.
They become fully independent after several years.
Is the blue whale an endangered species?
The blue whale is an endangered species listed as EN (Endangered) on the IUCN (International Union for Conservation of Nature) Red List. The estimated population is around 5,000 to 15,000 individuals. The problem was that because their blubber could be used as fuel, they were over-hunted along with humpback whales and baleen whales. Hunting was prohibited under the International Whaling Convention in 1966. Now, that number is on the rise.
- International Situation
IUCN (International Union for Conservation of Nature) Red List: Endangered
Originally widespread throughout the world’s oceans, populations plummeted due to commercial whaling in the 20th century.
Although populations are currently recovering, they have not yet reached the levels seen in the first half of the 20th century.
- Past Whaling Damage
From the 1900s to the 1960s, overfishing by commercial whaling was severe.
Blue whales were targeted for capture because their large bodies were easily exploited for fat and oil.
As a result, it is estimated that the world’s blue whale population has declined to about one-tenth of its former size.
- Current Threats
Commercial whaling is largely banned, but the following risks remain:
Collision: Accidents involving collisions with ships while sailing
Marine Debris and Plastic: Potential Health Damage from Accidental Ingestion
Climate Change: Changes in the Distribution and Abundance of Krill, Their Prey
Marine Noise: Low-Frequency Noise from Ships and Industrial Activities Affects Communication
- Conservation Status
Commercial whaling is banned by the International Whaling Commission (IWC).
Many countries have protective laws, prohibiting whaling for purposes other than tourism or scientific research.
In some ocean areas, migration routes are protected and monitored.
Can blue whales be kept in captivity?
Blue whales are not suitable for captivity. It is a very large animal, so we recommend that you admire it.
- Their Enormous Size
Adults are 25-30 meters long and weigh 100-200 tons.
Even young whales measure 7-8 meters and weigh 2-3 tons.
It is physically impossible to house such large bodies in an aquarium.
For example, even the world’s largest aquariums can only accommodate cetaceans up to around 10 meters in size.
- Highly Migratory
In the wild, they are a migratory species, traveling thousands of kilometers.
They require large ocean areas to swim long distances, and aquariums would be too stressful for them.
- Dietary Issues
They eat several tons of krill per day.
It is practically impossible to provide the same amount of food in an aquarium.
- Conservation and Legal Issues
Blue whales are an endangered species.
International and national conservation laws strictly restrict their capture and captivity.
Even if young whales were captured, their chances of survival are virtually zero.
- Current Captivity Status
Aquariums around the world primarily keep small whales such as killer whales, beluga whales, Pacific white-sided dolphins, and minke whales.
Blue whales can only be seen in the wild (whale watching).
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