Blue whale

Balaenoptera musculus

Blue whale Blue whale
The Blue whale is the biggest animal that has ever inhabited our planet.
Belonging to the so-called Rorqual family, which is more scientifically defined as the Balaenopteridae family, despite its size and weight the Blue Whale has a slender and very streamlined body. It is a fast swimmer and, as all the other members of its family, its throat presents the typical pleats, also called throat grooves. These are in numbers of 55 to 88. The head of the Blue whale is relatively flat and U-shaped, with a distinctive single, central ridge.
Its blow is unmistakable, reaching over 10 meters of height.
The dorsal fin is small if compared with the total animal length, and it is located 3/4 of the way down the back. The Blue Whale is a very shy animal, that is rarely encountered in the oceans.
Maybe due to its huge weight, it rarely breaches or displays any particularly acrobatic behaviour.
Unlike its cousin Fin whale, though, the Blue whale often raises its flukes out of the water when going for a deep dive. Gestation is about 12 months, and calving is every 2 or 3 years.
The newborn can be 6 metres long, and weigh up to 4 tons (4000 kg). Calves nurse for about 8 months and are weaned when they already measure 16 metres in length.
The record growth rate of Blue whale calves is easily explained by taking into account that they drink almost 400 liters of fat-rich milk every day. As in all Mysticeti, they have 2 blowholes and females are slightly larger than males.
The Blues we are able to encounter nowadays are smaller than the over 30 metre specimen of the past. As these animals never really stop to grow, we need to allow enough time for the relatively young individuals to reach their maximum size with age, as the oldest (and therefore biggest) specimen reaching and even exceeding 30 metres have been killed during whaling time. Blue whales can be divided into 3 populations: North Pacific, North Atlantic and Southern Hemisphere.
The North Pacific population seems to be the healthiest, having recovered to a number of at least 2000 individuals. On the other hand, only a few hundred individuals are left in the North Atlantic population, although there too they show signs of recovery. On the other hand, Blue whales in the Southern Hemisphere are not showing any signs of recovery. In both hemispheres the Blue whale migrates to high latitudes in the summer, where it feeds mostly on Krill.
In Antarctica, where the "big" and world-famous Euphausia superba species of krill finds its best conditions, the Blue whale, unlike other whale species, is also able to feed on smaller krill living close to the icy coastal waters (south of the 60° parallel). As for its conservation status, the Blue Whale is still considered Endangered.
Being a fast swimmer, this species was considered out of reach by whalers until the early 1900s, when the exploding harpoon gun was invented and whales could be chased with steam and diesel powered factory ships.
At the same time, new air-inflating techniques were developed, so that whales would not sink after been harpooned. With their very efficient new technologies, humans slaughtered the Blue whale to the edge of extinction. The massacre peaked in 1931 when over 29000 Blue Whales were killed in a single season (source: American Cetacean Society).
In 1966, the International Whaling Commission (IWC) eventually banned the hunting of Blue whales in all waters. By that time, the number of Blues was so reduced that whalers did not consider anymore their hunting as commercially viable and already focused on more abundant species. Because of whaling, some Blue whale populations may never recover. The Blue Whale is one of the most fascinating cetaceans we can see in the oceans.
Despite the very accurate studies scientists have carried out, some aspects of its life are still a mystery. In particular, we still do not know exactly where they breed and mating has never been observed.