Blue Whale
The Blue whale is the largest mammal, possibly the largest animal, to ever inhabit the earth. An average Blue whale is between 23-24.5 meters long, and weighs about 99,800 kg. A Blue Whale's tongue is so big that it is about the size of an elephant and 50 humans could stand in its mouth. Its heart is close to the size of a small car. A human baby could crawl through a Blue Whale's arteries, and a grown man could swim down the largest of them. Females are larger than males of the same age, the largest weighing as much as 136,000 kg!
Its body is long, somewhat tapered, and streamlined, with it’s broad, flat head making up less than one-fourth of its total body length. It’s U-shaped head includes a single ridge that extends just forward of the blowholes to the tip of the snout. Blue Whales have a pointed snout and paired blowholes. The position of their nostril is on the top of their head, creating blowholes. Their blowholes are contained in a large, raised "splash guard," and the blow is tall and straight and over 6 m high. A whale's blowhole generally reaches the surface before the rest of its body.
Its body is smooth and relatively free of parasites, but a few barnacles attach themselves to the edge of the fluke and occasionally to the tips of the flippers and to the dorsal fin. There are 55-68 ventral grooves or pleats extending from the lower jaw to near the navel. The throat grooves, in addition to streamlining the shape of the whale, allow the throat area to expand tremendously during feeding. This allows them to take in tons of food-laden water which is then discarded through their baleen plates leaving the fish or krill for swallowing. This efficient system enables the largest animals on earth to feed on some of the smallest. Their bodies are streamlined for efficient movement through the water; their flippers aid them in steering; their tails are broad and horizontal with 2 large flukes that help propel them powerfully through the water by moving up and down, rather than side to side like a fish; in place of hair they have a thick layer of fat called blubber under their skin that insulates them from the cold and provides buoyancy.
The Blue whale is blue-gray in color, but often with lighter gray mottling on a darker background (or with darker spots on a lighter background). The underside of its flippers may be a lighter color or white, while the ventral (topside) of the fluke is dark.
All Blue Whales are rorquals, a family that includes the Humpback Whale, the Fin Whale, the Bryde's Whale, the Sei Whale and the Minke Whale and belong to one of seven species of whale in the genus Balaenoptera. All members of the Order Cetacea (includes all whales, toothed and those using baleen) are believed to have evolved from terrestrial hoofed mammals like cows, camels and sheep some 45 million years ago — that's about 40 million years before humans. It is believed that the closest land-bound living relative of whales may be the hippopotamus. Throughout their evolution, cetaceans have become perfectly suited to an aquatic environment, and are virtually incapable of leaving it. Whales have developed unique ways of hearing and seeing. Hearing in particular is highly developed in whales, so much so that they depend on it in the same way that we depend on the combination of our eyes, ears and nose to understand the world around us. Whales do not have external ears, but rely on an internal system of air sinuses and bones to detect sounds.
The lifespan is estimated at 80 years or longer for these large animals. The longest recorded study of a single individual is thirty-four years, in the north-east Pacific. Whales don't sleep like you and me. If they did, they would drown. Instead, whales take very short naps, often floating near the surface of the ocean. Their only natural predator is the Orca and many Blue whales having scarring from these attacks.
Though they may be found singly or in small groups, it is more common to see Blue whales in pairs. Aggregations of up to 60 animals have been reported, but solitary animals or pods of 2-3 are more common. It is not known whether those that travel in pairs stay together over many years or form more loose relationships. In areas of very high food concentration, as many as 50 Blue Whales have been seen scattered over a small area. However, they do not form large close-knit groups as seen in other baleen species. Like Humpbacks, Blue whales also sing or call. The Blue Whale is the loudest animal in the world. Blue Whales off the coast of Sri Lanka have been recorded making "songs" of four notes duration lasting about two minutes each They are fast, strong swimmers, capable of reaching 49.3 kph when alarmed, but they usually cruise along at about 19.3 kph. Normal dives last from 10-20 minutes and are separated by 8-15 blows.
Scientific Name : Balaenoptera musculus
Balaenoptera musculus musculus (Northern blue whale: N. Atlantic, N. Pacific)
Balaenoptera musculus intermedia (Southern blue whale: S. Ocean)
Balaenoptera musculus indica (Indian Ocean blue whale: Indian Ocean)
Balaenoptera musculus brevicauda (Pygmy blue whale)
Encounters
Blue whales may be found in all oceans of the world. They mate and calve in tropical-to-temperate waters during winter months and feed in polar waters during summer months. Blue whales in the northern hemisphere move north to Arctic waters to feed; Blue whales in the southern hemisphere move south to the Antarctic to feed. Nearly all the southern hemisphere population may be found in the summer feeding grounds in the Antarctic. We know blue whales migrate from polar waters where they feed to warmer, temperate waters where they breed and have babies. But no one's sure how blue whales navigate these long distances. It's possible that they have the ability to detect the Earth's magnetic field and use it as a map or a compass.
Diet
The Blue whale is thought to feed almost exclusively on small, shrimp-like creatures called krill, a type of zooplankton. The whales always feed on the highest concentration of krill that they can find. This means that they typically feed at depth (more than 100 m) during the daytimes, and only surface feed at night. During the summer feeding season the Blue whale gorges itself, consuming an astounding 3,600 kg or more each day. This means it may eat up to 40 million krill a day. As a baleen whale, it has a series of 260-400 fringed overlapping plates hanging from each side of the upper jaw, where teeth might otherwise be located. These plates consist of a fingernail-like material called keratin that frays out into fine hairs on the ends inside the mouth near the tongue. During feeding, large volumes of water and food can be taken into the mouth because the pleated grooves in the throat expand. As the mouth closes water is expelled through the baleen plates, which trap the food on the inside near the tongue to be swallowed.
Reproduction
Recent research indicates that Blue whales reach sexual maturity between the ages of 6-10 years, or when males average about 23 m and females are about 24 m. Calves are born at intervals of 2 to 3 years during the start of the winter and gestation is about 12 months. Calves are 7-8.2 m long at birth and 2,722 kg. Calves nurse for 7 to 8 months and are weaned when they reach 16 m in length. At that time they weigh about 20,900 kg. During the nursing period, calves consume 379 liters of the fat-rich mother's milk each day, gain 91 kg/day, or 3.9 kg/hour, and grow 3.78 cm in length a day.
Conservation
There are only between 1,300- 2,000 Blue whales left. They face threats from entanglement, pollution, and illegal whaling. The Blue Whale remains listed as "endangered" on the IUCN Red List of threatened species as it has been since the list's inception. The largest known concentration, consisting of about 2,000 individuals, is the North-East Pacific population that ranges from Alaska to Costa Rica, but is most commonly seen from California in summer. This group represents the best hope for a long-term recovery in Blue Whale population.
Because of their enormous size and speed, Blue whales were safe from early whalers, who could not pursue them in open boats with hand harpoons. But in 1868 a Norwegian, Sven Foyn, revolutionized the whaling industry with the invention of the exploding harpoon gun and by using steam and diesel powered factory ships and catcher boats. He also perfected the technique of inflating dead whales with air so they wouldn't sink after being harpooned. The whaling industry began to focus on Blue whales after 1900. A single 27 m Blue whale could yield up to 120 barrels of oil, and the Blues were killed by the thousands. The slaughter peaked in 1931 when over 29,000 were killed in one season.
After that Blue whales became so scarce that the whalers turned to other species and, belatedly, the International Whaling Commission (IWC) banned all hunting of Blue whales in 1966 and gave them worldwide protection. Recovery has been extremely slow, and only in the last few years have there been signs that their numbers may be increasing. Pre-whaling numbers have been estimated at 200,000, and though exact figures are not known, an estimated 5,000 survive today in three populations: North Atlantic, North Pacific, and the Southern Hemisphere. Imagine what it would be like to be the biggest animal in the world swimming alone through the cold ocean waters.
