Blue Whales The Blue whale is the largest creature of the sea; in fact, its the largest creature known to man. Contrary to what most people think, even though Blue whales live in the sea, they are mammals. They breathe air, have their babies born alive, and can live anywhere from 30 to 70 years. The Blue whale is a baleen whale, and instead of having teeth, Blue whales have around 300-400 baleen plates in their mouths. Baleen are rows of coarse, bristle-like fibers used to strain plankton from the water. Baleen is made of keratin, the same material as our fingernails.
The Blue whale is called a rorqual, a Norwegian word for furrow referring to the pleated grooves running from its chin to its naval. The pleated throat grooves allow the Blue whales throat to expand during the huge intake of water during filter feeding; they can hold 1,000 tons or more of food and water when fully expanded (Small 1971). They average about 50-70 throat grooves. Blue whales grow up to about 80 feet (25m) long on average, weighing about 120 tons. The females are generally larger than the males, this is the case for all baleen whales.
The largest specimen found was a female 94 feet (29m) long weighing more than 174 tons (Satchell 1998). The head of the Blue whale forms up to a quarter of the total body length. Compared with other rorquals, the head is very broad. The blue whale heart is also large, the size of a small car and can pump almost 10 tons of blood throughout the body. They also have a very small, falcate (sickle-shaped) dorsal fin that is located near the fluke, or tail. Blue whales have long, thin flippers 8 feet (2. 4m) long and flukes that are 25feet (7. m) wide. The blue whales skin is usually blue-gray with white-gray spots. The underbelly has brown, yellow, or gray specks. During the winter, in cold waters, diatoms stick to the underbelly, giving it a yellow to silver- to sulfur-colored sheen; giving the blue whale its nick-name of sulfur bottoms. Other names include Sibbalds Rorqual and Great Northern Rorqual. Blue whales (like all baleen whales) are seasonal feeders and carnivores that filter feed tiny crustaceans (krill, copepods, etc), plankton, and small fish from the water.
Krill, or shrimp-like euphasiids are no longer than 3 inches. It is amazing that the worlds largest animals feed on the smallest marine life. Blue whales are gulpers, filter feeders that alternatively swim, then gulp a mouthful of plankton or fish. An average-sized blue whale will eat 2,000-9,000 pounds (900- 4100kg) of plankton each day during the summer feeding season in cold, arctic waters (120 days) (Hasley 1984). The blue whale has twin blowholes with exceptionally large fleshy splashguards to the front and sides.
It has about 320 pairs of black baleen plates with dark gray bristles in the blue whales jaws. These plates can be 35-39 inches (90cm-1m) long, 21 inches (53cm) wide, and weigh 200 pounds (90kg). The tongue weighs 4 tons. Blue whales live individually or in very small pods (groups). They frequently swim in pairs. When the whale comes to the surface of the water, it takes a large breath of air. Then it dives back into the water, going to a depth of 350 feet (105m). Diving is also the way in which whales catch most of their food.
Whales can stay under water for up to two hours without coming to the surface for more air. Blue whales breath air at the surface of the water through 2 blowholes located near the top of the head. They breathe about 1-4 times per minute at rest, and 5-12 times per minute after a deep dive (Hasley 1984) Their blow is a single stream that rises 40-50 feet (12-15m) above the surface of the water. They are also very fast swimmers; they normally swim 3-20 mph, but can go up to 24-30mph in bursts when in danger.
Feeding speeds are slower, usually about 1-4mph. The whales emit very loud, highly structured, repetitive low-frequency sounds that can travel form many miles underwater. They are probably the loudest animals alive, louder than a jet engine. These songs may be used for locating large masses of krill (tiny crustaceans that they eat) and for communicating with other blue whales. Blue whales typically are found in the open ocean and live at the surface. They are found in all the oceans of the world.
The majority of Blue whales live in the Southern Hemisphere. The sub-species found in the Southern Hemisphere are the balaenoptera musculus. The smaller populations inhabit the North Atlantic and North Pacific. These Northern Hemisphere Blue whales are the balaenoptera brevicauda. They migrate long distances between low latitude winter mating grounds and high latitude summer feeding grounds. They are often seen in parts of California, Gulf of California (Sea of Cortez), Gulf of St. Lawrence, Canada and the northern Indian Ocean.
Blue whale breeding occurs mostly in the winter to early spring while near the surface and in warm waters. The gestation period is about 11-12 months and the calf is born tail first (this is normal for cetaceans) and near the surface in warm, shallow waters (Hasley 1984). The newborn instinctively swims to the surface within 10 seconds for its first breath; it is helped by its mother, using her flippers. Within 30 minutes of its birth the baby whale can swim. The newborn calf is about 25 feet (7. 6m) long and weighs 6-8 tons.
Twins are extremely rare (about 1% of births); there is almost always one calf. The baby is nurtured with its mothers fat-laden milk (it is about 40-50% fat) and is weaned in about 7-8 months. A calf may drink 50 gallons of mothers milk and gain up to 9 pounds an hour or 200 pounds a day. The mother and calf may stay together for a year or longer, when the calf is about 45 feet (13m) long. Blue whales reach maturity at 10-15 years. They also have a life expectancy of 35-40 years. However, there are many factors that limit the life span of the Blue whale.
Packs of killer whales (orcas) have been known to attack and kill young blue whales or calves. Man also hunted blue whales until the International Whaling Commission declared them to be a protected species in 1966 because of a huge decrease in their population. The Blue whale was too swift and powerful for the 19th century whalers to hunt, but with the arrival of harpoon canons, they became a much sought after species for their large amounts of blubber. They were also hunted years ago for their baleen, which was used to make brushes and corsets.
But it was their size and high yield of oil that made them the target of choice for modern commercial whalers. Before mans intervention there were 228,000 Blue whales swimming the oceans of the world. Between 1904 and 1978, whalers scoured the seas for this huge cetacean, most were taken in the Southern Hemisphere, many illegally (Satchell 1998). As the population figure suggests, it was relentlessly slaughtered for every reason imaginable, almost to the point of extinction. Another reason why Blue whales are almost extinct is pollution.
Most of their illnesses are contracted by pollution. It is estimated that there are about 10,000-14,000 blue whales world-wide. Blue whales are an endangered species. They have been protected worldwide by international law, since 1967. The blue whale was listed as endangered throughout its range on June 2, 1970 under Section 7 of the Endangered Species Conservation Act of 1969. They are not to be hunted by anyone for any reason at all. Suggestions are that some populations may never recover.