Blue Whale

Blue whales are marine mammals and the largest animals ever known to have lived on Earth. They feed almost entirely on krill, straining their baleen plates with immense amounts of ocean water. Some of the largest individuals can eat up to 6 tons of krill in one day.

What is the Blue Whale Scientific Name?

The blue whale scientific name is Balaenoptera musculus. There are currently four blue whale subspecies, recognised by the Society for Marine Mammalogy’s Committee on Taxonomy. 

• Balaenoptera musculus in the North Atlantic and North Pacific.

• Balaenoptera musculus intermedia in the Southern Ocean.

• Balaenoptera musculus brevicauda (Pygmy blue whale) in the Indian Ocean and South Pacific Ocean. 

• Balaenoptera musculus indica in the Northern Indian Ocean.

Blue Whale Morphology

Blue whales have long, slender, mottled greyish-blue bodies, but they tend to be blue underwater. The mottling pattern is highly variable and it is possible to use the distinctive pattern of pigmentation along the back in the dorsal fin area to distinguish recognized individuals. 

A large, flat head, which appears U-shaped from above, contains additional distinguishing features of the Blue Whale fish as follows:

• Blue Whale has 270-395 entirely black baleen plates on either side of their upper jaw.

• It has 60-88 expandable throat pleats.

• Long, slender flippers.

• A small falcate dorsal fin situated far back towards the tail.

• A thick tailstock.

• A huge, slender fluke.

Blue Whale Facts

Blue Whale Size

Blue whale length of up to 31m (102 ft) were documented by the Discovery Committee. The longest individual blue whale scientifically measured, however, was 29.9 m (98 ft). 

The Blue whale length of the female is bigger than males. Hydrodynamic simulations indicate that, because of metabolic and energy constraints, a blue whale could not exceed more than 33 m (108 ft).

Let us look into Blue whale lengths of different subspecies. The blue whale length in feet is given in brackets.

• In the eastern North Pacific region, the average blue whale length is 22.1 m (72.1 ft).

• In the central and western North Pacific region, the blue whale length is 24.1 m (79 ft).

• In the North Atlantic region, the blue whale length is 28.1 m (92 ft).

• For Antarctic blue whales, the length varies from 25.4–26.6 m (83.4–86.3 ft).

• For Chilean blue whales, the length is 23.5 m (77.1 ft).

• The length of blue whale pygmies found in the Indian Ocean and South Pacific Ocean is 21.3 m (69.9 ft) long.

The blue whale height of all species varies typically between 3.96-4.88 m. 

Blue Whale Weight

When we see the enormous blue whale, the first question that pops in our brain is “What is the weight of blue whale?”

The average Blue whale weight of different subspecies is given as below:

• In the Northern Hemisphere region, Blue whale males weigh an average of 100 tons, and females weigh 112 tons.

• In the Eastern North Pacific Blue whale males weigh an average of 88.5 tons, and females weigh 100 tons.

• In the Antarctic region, males weigh an average of 112 tons and females weigh an average of 130 tons.

• The average male Pygmy Blue Whale is 83.5 and the female blue whale is 99 tons.

It has to be noted that the Blue whale weight of the female is always more than male.

The largest blue whale weight is 190 tonnes female blue whale which was hunted in the Southern Ocean, Antarctica on 20 March 1947.  The weight of the largest blue whale is equivalent to about 30 elephants or 2500 people. 

Blue Whale Lifespan

During the study of Blue whales, the first question we get is “What is the lifespan of a blue whale?” and how do we calculate the Blue whale lifespan.

From ear plugs, the most accurate age estimation of the Blue whale is done. Throughout their lives, blue whales secrete earwax (cerumen), forming long, multilayered plugs. Every light and dark layer (lamina) deposited chronologically indicates a transition between fasting during migration and feeding, and one set is laid down each year, so, the number of these layers can be used as an age indicator.

For a pygmy whale, the maximum age calculated from earplug laminae is 73 years. It was estimated that the oldest blue whale detected using this earplug process was about 110 years old. The average Blue whale lifespan is around 80 to 90 years.

Blue Whale Habitat

In all oceans except the Arctic, blue whales are present. They usually migrate between summer feeding grounds and winter breeding grounds seasonally, although some evidence indicates that they stay year-round in some areas. 

Distribution and movement information vary with region, and migratory routes are not well-known. Distribution is usually influenced primarily by the availability of food, which occurs in waters where krill is concentrated.

Let Us Look About Blue Whale Different Habitats:

• In the North Atlantic Ocean, their range extends to the Greenland Sea from the subtropics. 

• In the waters off eastern Canada, in the shelf waters of the eastern United States, and infrequently in the Gulf of Mexico and the Caribbean, blue whales have been seen.

• The eastern North Pacific blue whales are thought to spend winters off Mexico and Central America along the West Coast of the United States. They're probably feeding off the U.S. during summer. 

• The West Coast and, to a lesser degree, the Alaskan Gulf and the central waters of the North Pacific.

• In the Gulf of California (Sea of Cortez), blue whales with young calves are regularly observed from December through March. It is also assumed that, for the species, this area is likely to be a significant calving and nursing area.

• There is a residential community in the northern Indian Ocean. From the Gulf of Aden, the Arabian Sea and across the Bay of Bengal, blue whale sightings, strandings and acoustic detections have been recorded. These whale migratory movements are mostly unknown but may be influenced by monsoon-related oceanographic shifts.

• Antarctic blue whales occur mostly in relatively high latitude waters south of the Antarctic Convergence in the Southern Hemisphere and close to the ice edge in summer. Generally, in winter, they migrate to middle and low latitudes, but not all whales migrate every year.

• North of the Antarctic Convergence, pygmy blue whales are usually distributed and are most common in waters off Australia, Madagascar, and New Zealand. 

• In the southeastern Pacific Ocean, especially in the Chinese Ecoregion, an unidentified blue whale subspecies is found and migrates to lower latitude areas, including the Galapagos Islands and the eastern tropical Pacific.

Blue Whale Diet

Krill, tiny shrimp-like creatures, are the main and preferred diet of blue whales. Sometimes, fish and copepods (tiny crustaceans) can be part of the diet of the blue whale. When blue whales search for food, they filter feed by swimming with their mouth open towards large schools of krill, then force the water with their tongue out of their mouth while holding the krill trapped within their baleen plates.

Blue Whale Reproduction

While studying the reproduction of blue whales, we think about whether is a blue whale a mammal or not. Blue whales are actually the largest living mammals on earth. More blue whale information regarding reproduction is given below.

Blue whales have been estimated to reach sexual maturity at around 10 years of age and an average length of 23.5 m for female Antarctic blue whales, using the amount of earwax lamina accumulated in an earplug and the production of sexual organs from dead whales.

The best available evidence suggests that the gestation period is about 10 to 12 months and that for around 6 to 7 months, blue whale calves are nursed. Weaning occurs in summer feeding areas. It is assumed that the age of sexual maturity is 5 to 15 years. The bulk of reproductive activity takes place during the winter, including births and mating. The typical calving period is possibly between 2 and 3 years.

From birth until weaning, blue whales show no well-defined social structure other than mother-calf bonds. Generally, they are solitary or present in small groups. On mating activity, or breeding and birthing areas, little is understood.

Vocalization of Blue Whales

Among the loudest and lowest frequency sounds made by any species are blue whale vocalizations. For blue whale vocalizations, the fundamental frequency varies from 8 to 25 Hz. They emit a series of pulses, groans, and moans, and it is believed that blue whales can hear each other up to 1,000 miles away in good conditions.

Scientists claim they use these vocalizations not only to communicate but to sonar-navigate the lightless ocean depths together with their excellent hearing.

Blue Whale Population

The number of blue whales in the oceans of the world is just a small fraction of what it was before their numbers were drastically diminished by modern commercial whaling during the early 1900s, but populations are growing globally. Today, under the Endangered Species Act, blue whales are listed as endangered. Vessel strikes and entanglements in fishing gear are the main threats currently facing blue whales. 

Blue whales are significantly depleted by commercial whaling activities globally. The global density of the blue whale population is estimated to be 10,000-25,000 blue whales, approximately 3-11% of the estimated population size in 1911.

Major Threats to the Blue Whale Population

Most of the threats which are endangering the blue whale population are Anthropogenic in nature i.e. Man-made threats. The following are a few of the threats which are endangering the blue whale population.

• Vessel strikes - Strikes by vessels can injure or kill blue whales. Vessel strikes across their range have killed blue whales, but in some coastal areas with heavy vessel traffic, the risk is even greater. Nine blue whales were reported to have been killed off California by ship strikes between 2007 and 2010. Eleven blue whales were killed by ship strikes around Sri Lanka between 2010 and 2012, and at least two in 2014.

• Entanglement - In fishing gear, blue whales may become entangled, either swimming off with the gear attached or getting anchored. In several different gear types, including traps, pots, and gillnets, blue whales may become entangled. When entangled, whales can drag and swim for long distances with attached gear, eventually resulting in tiredness, diminished feeding ability, or serious injury, which can lead to decreased reproductive success and death.

• Ocean noise - Exposure to anthropogenic sound can result in a variety of behavioural responses, in addition to masking blue whale contact ranges.

• Pollutants - There is no knowledge of the possible effect of toxins on blue whales. However, since blue whales eat less on the food chain, organic chemical pollutants are less likely to bioaccumulate.

• Plastics - As a result of filter-feeding activity, baleen whales are vulnerable to plastic ingestion.

Blue Whale conservation

Blue whales are listed federally as endangered. This species was once plentiful, but it was made easier for people to hunt them by advancements in whaling technology. Blue whale numbers have plummeted with the rise of factory ships. They are now covered by a moratorium on whaling worldwide, and their numbers are increasing.

In areas with high human traffic, ship noise, entanglement, and collisions can impact them, but occurrences of these events are uncommon. It is unclear the impact that climate change would have on blue whales.

Fun Blue Whale Facts

• Blue whales are the loudest animals on Earth. Their songs can reach nearly 200 decibels which is louder than a jet engine.

• Some of the smallest marine life, tiny shrimps like species called krill, are fed by the Blue Whale. 36,000 kg of krill a day can be eaten by a single adult blue whale.

• At more than 8 km/h, blue whales are graceful swimmers that cruise the ocean and can achieve speeds of over 30 km/h.