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Dissecting Blue Whales

A look inside the largest mammal in the world

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Introduction

Blue whales are the largest living beings in the world. The marine mammal is scientifically known as Balaenoptera musculus. It is classified as endangered but its population is increasing. Blue whales are hunted for its oil, blubber and also meat.

Numbers

1. From 1868–1978, 3,82,595 whales were hunted.
2. Currently, there are around 10,000–25,000 blue whales, which is around 3%-11% of its population in 1911.
3. Eastern North Pacific — 1,647, Central North Pacific — 63–133, North Atlantic — 1000–2,000, Antarctic — 2,280, New Zealand — 718, Northern Indian Ocean — 270, and Chile — 570–760.

Size and Features

1. Blue whales have a greyish-blue body although they appear to be blue underwater.
2. Though it is a deep water hunter, it has to come to the ocean surface to breathe because it is a mammal.
3. Its heart is the size of a Volkswagen Beetle, its tongue weighs as much as an elephant, and there is enough space to swim through its blood vessels.
4. They can grow up to the size of 29.9 metres (98 feet) and a weight of 177 tonnes (190 tons) (approximately 33 elephants)
5. Their dorsal fin can identify individual whales and have irregular mottling patterns and pigmentation.
6. Their broad, flat head appear U-shaped from above.
7. 270–395 black baleen plates on each side of the upper jaw, 60–88 expandable; slender, long flippers, a small dorsal fin to the back, and thick tail.
8. Pale underside that can accommodate diatom coat (algae) and two blowholes that can spray water up to 9–12 metres.
9. The longest estimated blue whale is 33 metres, but the confirmed one is 29.9 metres.
10. It is suggested through hydrodynamic models that a blue whale cannot grow more than 33 metres due to energy and metabolic constraints.
11. Females blue whales are larger than males.

Lifespan

1. It has a lifespan of around 80–90 years and the highest measured is 110 years.
2. The age of blue whales can be measured by counting their earwax plugs.
3. Layers of baleen plates were used previously, but it proved to be unreliable.
4. Another way is to count the number of scars in the ovaries of a female blue whale. Roughly, one corpus Albicans is formed every 2.6 years.

Speed

1. Though they swim in small groups, they usually spend time alone.
2. Their normal cruise speed is around 7.4 kmph but when agitated they are known to travel at 20–48 kmph. They usually travel around 58–172 kilometres per day.

Sound

1. They are the loudest animal in the world and can reach up to 188 decibels. It is said that, in good conditions, blue whales can hear each other from a distance of 1600 kilometres.

Diet

1. Their diet mainly consists of Krills — a shrimp-like animal which whales are said to have around 4 tonnes a day. They can consume 34,776–1,912,680 kJ (~480,000 kilocalories) in one mouthful

Breeding

1. Female blue whales only breed once every three years and they have a gestation period of 11–12 months.
2. Blue whale calves are around 3 tons heavy and 25 feet long. They come to the world as the largest animal in the world. They feed on only mother’s milk and gain around 200 pounds every day for the first year. They reach sexual maturity at around the age of 9–10 years.

Hunting

1. They were abundantly available until the end of the 19th century.
2. But constant hunting got them to the brink of extinction.
3. Hunting of whales was banned in 1966 or 1967 by the International Whaling Commission.
4. The International Whaling Commission was set up in 1946.

Whale Watching

1. Whale Watching is prevalent in North Pacific, North Atlantic, Iceland, Sri Lanka, Chile, Perth Canyon and New Zealand.
2. Specific guidelines have to be followed while watching whales such as not move into the path of a whale, move faster than a whale, make erratic speed or directional changes unless to avoid collision, get between two whales, chase, feed, or touch the whales, and stay at least 100 yards away from them.

Migration

1. Blue Whales migrate due to many reasons. To reduce competition, parasitism and pathogens, reduce calf predation from orcas, provide greater access to prey in spring and summer, and optimise thermoregulation for growth in the winter.
2. Higher latitudes for feeding and lower latitudes for breeding is the common pattern of migration seen in whales. But their movement is not consistent.
3. Hybridisation in whales is a much-debated concept.

Threats

Despite being the largest living being, Blue Whales do face certain threats such as ship strikes, entanglement, ocean noise, climate change, plastics, oil, pollutants, diseases due to toxins, predators, and competition.

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Originally published at https://www.writerandgeek.com on March 9, 2020.

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