Blue Whales : Get to know about the largest animals on Earth

After the Earth started to exhibit the first signs of live, numerous animals have roamed on it. From small to ridiculously large animals, the Earth has seen it all. But as the Earth underwent evolution and faces drastic change in composition of environment, the Earth adapted itself according to it and so as the creatures on it. Today we are going to learn about that animal which also underwent evolution and are currently holding the title of the largest animal on planet Earth. Many other creatures who are slightly bigger than them, also roamed on the Earth, but what makes these modern giants so adaptable to the present conditions ?. These giants are the "Blue whales" which belongs from the family of giant marine animals known as "Rorquals (Balaenopteridae)" or we can say from the group of Baleen whales. These giant whales came into existence in around 4.5 million years ago. Let's learn about the physical and biological characteristics that theses whales have to offer and what makes them different from the other marine animals. Let's start.

Balaenoptera musculus (Blue Whale)

General Info

Blue whales are large migratory carnivorous marine mammals which can be found in all the oceans in the world, except the Arctic ocean. These giants are known for being the largest mammals and the largest animals in the world. It is said that they were discovered in 1868 by the International Whaling Commission. There are 4 recognized sub-species of blue whales (and the 5th one is unnamed) which is made on the basis of their location or region. These sub-species consists of further sub-species in them. These are:

1) B. M. musculus (Northern blue whales)

• North Atlantic population

• Eastern North Pacific population

• Central and western North pacific population

2) B. M. brevicauda (Pygmy blue whales)

• Madagascar population

• Eastern Australia/New Zealand population

• Western Australia/Indonesia population

3) B. M. intermedia (Antarctic blue whales)

4) B. M. indica 

5) Unnamed sub-species/B. M. unnamed (Chilean blue whales)

The total population of blue whale is around 25,000 and are considered to be threatened species, as they are on the spot of  "Endangered (EN)" species on the the IUCN red list. Also, their lifespan is around 80 to 90 years.

Physical Characteristics 

Blue whales are massively large-sized animals with a big flat U-shaped (from above) head and a long tapered body. They have a greyish blue body color with a yellowish under belly, although they look completely blue underwater due to reflection and refraction of light.

Their size can be anywhere from 69.9 to 102 feet (21.3 to 31 meters) depending upon the sub-specie and gender as the female blue whales are larger than the male blue whales. As for their weight, their average weight is around 83.5 to 165 tonne (83,500 to 165,000 Kg Or 184306.5 to 363,763 pounds), which is way less than the maximum weight which they can attain, which is up to 200 tons (200,000 Kg or 418,878 pounds), which again depends upon the area and gender. However the largest blue whale was a female with a length of 110.17 feet (33.58 meters). Also, the heaviest blue whaler recorded was also a female weighing around 190 tonne (190,000 Kg Or 418,878 pounds).

Behavior and Lifestyle

Blue whale mostly live alone but sometime they are also spotted in small groups or pairs, which mostly happens around the breeding seaon. Blue whales are not apex predators like sharks and killer whales and thus they are not aggressive and do not posses any danger to any humans. Blue whales are migratory mammals. They mostly migrate in winter season for breeding and in the search of food sources. Also, migrating to other areas help them to keep their babies safe from predators for a long time, which give the baby some time to grow.

They swim around 60 to 170 Km per day with an average speed ranging from 0.88 to 4.45 miles per hour (1.43 to 7.17 Km/h). Although, the maximum speeds ever recorded or observed ranges 12.42 to 29.82 miles per hour (from 20 to 48 Km/h), which blue whales only uses if they are chased, spooked or attacked.

As for their diet, they mainly feed on krill which they eat through the process of filter feeding. They can eat up to 6 tons (5.44 tonne or 5443.11 Kg) of krill everyday. But sometimes they also feed upon small fishes, but only by accident, as the primary source of food of them are krills only.

Biological Features

Sexual Dimorphism

Blue whales show sexual dimorphism, which in their case, the females are bigger and heavier as compared to the male blue whales.

Sound frequency 

The frequency of sounds made by blue whales are considered to be one of the loudest and the lowest frequency sounds in the animal kingdom. Their calling sounds ranges from 18 to 108 Hz on an average. The human hearing threshold starts from 0 decibels (dB) and blue whale normally make noise above 70 decibels (dB), which means the sound produced by them are very loud to human ear and may result in causing damage to the hearing.

Hybridization 

Blue whale biological anatomy and cellular features are supportive towards hybridization.

FAQ

Is it true that their tongues weigh as same as that of an elephant and their heart weigh as same as that of an automobile ?

Yes it is true that their tongue are really heavy. Their tongue weighs around 8,000 pounds (3628.74 Kg), which is greater the weights of most of the species of elephants (except bigger species like the African Elephants). As for their heart, yes the are also really big and heavy and can weigh around 400 pounds (181.43 Kg), which not greater than regular sized cars but are surely equal to or greater than bumper cars.

Reproduction

Both female and male blue whales reach the stage of sexual maturity at the age of 10 years. They migrate during the mating season to find partners. According to the researchers, blue whale mate and give birth to the babies in the winter seasons. 

After the gestation period of 11 to 12 months the female blue whale give birth to one baby. Depending upon the sub-specie, blue whales give birth after every 2 to3 years. The young blue whales weighs around 8818 pounds (4000 Kg) and are around 26 feet (7.92 meters) in length. Also, their growth rate rapid which helps them in gaining around 200 pounds (90.7 Kg) everyday.

Fact and Summary 

• Blue whales are very large-sized marine carnivorous mammals which can be found in all the oceans in the world, except the Arctic ocean.

• It is said that they were discovered in 1868 by the International Whaling Commission.

• There are 4 recognized sub-species of blue whales (and the 5th one is unnamed) which is made on the basis of their location or region. These sub-species consists of further sub-species in them.

• Their lifespan is around 80 to 90 years.

• Blue whales are migratory animals and migrate to warmer tropical water during the breeding/mating season.

• Blue whales are not as blue as they appear to be underwater. They are actually greyish-blue in color with a yellowish underbelly. They appear blue underwater due to the reflection and refraction of light.

• They mainly feed on krill and can eat up to 6 tons (5.44 tonne or 5443.11 Kg) of krill everyday, which is around 40 million of them ! .
• They are one of the loudest sound making animals (sounds with one of the lowest frequencies in the animals kingdom).

• A blue whale's heart weighs as same as that of a bumper car and their tongue can weigh more than most of the species of elephants (See FAQ above).

• The Blue whale babies are the most biggest and heaviest babies in the animals kingdom. The young blue whales weighs around 8818 pounds (4000 Kg) and are around 26 feet (7.92 meters) in length.

• Also, the growth rate of blue babies is considered to be one of the most fastest. They can gain around 200 pounds (90.7 Kg) everyday.

• Not specifically for the blue whales, but a group of whales in general is called as "Pods".

• Some says that the Blue whales are largest animals ever existed on planet Earth, although according to researchers, there maybe other creatures too, especially from the Triassic and Jurassic period, that are said to be larger than the blue whales. Fossils and other proofs make this clear, although some specimens maybe be an exception therefore this topic is still debatable.

• Blue whales are considered to be endangered species.

• Blue whales (or any whale) are mammals and are not in category of fishes as they have lungs instead of gills, therefore they have to come water surface to breathe. They can hold their breathe up to 90 minutes underwater, although they usually come back to the water surface in less than 30 minutes.

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