Tuesday, November 25, 2014

The Largest Creature the World Has Ever Known

Balaenoptera musculus, more commonly known as the blue whale, is said to be the rarest and most endangered of the great whales. This organism belongs to the order Cetacea, which includes whales, dolphins and porpoises.

Habitat Range
Typically, the blue whale can be found in cold or temperate waters and occur in almost every ocean including the Arctic Ocean, Atlantic Ocean, Indian Ocean and the Pacific Ocean. In the North Atlantic Ocean, these whales can range from the subtropics to the Greenland Sea. Moreover, these whales are seen frequently in the Gulf of St. Lawrence off the coast of eastern Canada. Most will migrate seasonally, but some studies show that others will stay in the same area year round. Migratory routes are not well known, and distributions vary in different areas. In general, individuals that live in the northern hemisphere will travel further north to Arctic waters in order to feed, while individuals in the southern hemisphere travel further south to the Antarctic to feed. In other words, they seem to migrate based on where food is more abundant, or where krill is more concentrated.

Physical Description
The blue whale is the largest mammal and animal alive today. It weighs in at about 200 tons, or 400,000 pounds and can be between eighty to one hundred feet in length. This is roughly the size of thirty three elephants. However, the largest of these whales was recorded to be about 110 feet in length. While all of these whales are large, the females are typically about ten meters longer than males. They are a lightly mottled blue/grey color with a light grey or yellow underside. This yellow coloring comes from a buildup of diatoms, or microscopic, unicellular marine algae. These vertebrates can be identified by their relatively small dorsal fin as well as their fairly rounded rostrum, or anterior part of their skull. Each whale is said to have approximately ninety ventral grooves which reach the navel. Also, they have about 300-400 baleen plates on each side of their mouth, which are usually black in color.

Evolutionary History
It is said that all members of Cetacea, which includes all whales with teeth and baleen, evolved from terrestrial hoofed animals, such as the modern day cow, camel, etc. some forty-five million years ago. To add to this belief, a recent study of milk protein genes in both whales and these hoofed animals may help to confirm this idea. This study also showed that the closest living relative of all whales is the hippopotamus. Blue whales, as well as all whales, are an example of adaptive radiation, meaning they have undergone many changes in order to thrive in their specific environments. For whales, this was to be able to survive in a marine habitat. Some changes that whales have undergone are that their bodies became streamlined for efficient movement in water, their forelimbs were modified into flippers, their hind limbs have just about disappeared completely, their tail broadened horizontally and now consists of two large flukes that help propel them powerfully through water, they have developed blubber, a fatty substance located just under the skin, for insulation and buoyancy instead of hair or fur, and, lastly, their nostrils have shifted to the top of their head to create the blowhole.

As far as predation goes, the blue whale really only seems to have one predator- humans. Occasionally, Orcas will attack and sometimes even kill a young blue whale. Lampreys have also been known to attach themselves to a blue whale and take a bite out of it, but there is no record of them killing the whale. Moreover, according to an article published in Huffington Post, blue whales seem to have a mutual relationship with dolphins in that dolphins will hitch a ride with a blue whale. The dolphins position themselves in the front of the whale and ride the pressure wave that the whale creates with its massive body size. However, blue whales are also very good at interacting with each other. According to National Geographic, blue whales have developed a few sophisticated ways to communicate across broad oceans. They use this sound for multiple purposes such as to locate food, navigate and communicate with one another. These methods of communication are important because blue whales live a solitary lifestyle and are usually found alone. Therefore, they need this advanced communication to locate each other. With as large as the blue whales are, they have an equally deep voice. They can vocalize at frequencies as low as 14 Hz. The volume of these sounds can also reach up to 180 decibels, which makes the blue whale the loudest animal on the planet. These modes of communication come in the forms of grunts, humming, moaning and clicks.

Conservation Status
According to World Wide Fund for Nature (WWF), as of right now, the Blue Whale is ranked as endangered and can no longer be found off the coast of Japan, the Gulf of Alaska nor in the Southern Bering Sea. Only a few hundred are said to be found in the Antarctic. According to a study published in September of 2014, which was performed in California by the University of Washington, the only known population that seems to be rebounding as of late is in the North Pacific off the coast of California, where the population of blue whales has grown to approximately two thousand individuals. Prior to whaling, it is said that there may have been more than 250,000 total individuals. Now, there are roughly 10,000 individuals across their habitat range. Some conditions that have led to this decline in the blue whale populations are that habitats are being lost to landfills, harbors, shipping canals and fisheries. Some other reasons are resort development and increased boat traffic. Currently, the WWF is placing satellite tracking devices on specific whales in order to observe which routes they seem to be taking the most often. This information can then be relayed to large shipping companies and fisheries so that they do not further harm this species.

Interesting Facts 
As stated under the physical description, the blue whale is the largest mammal and animal in the world. With that being said, it can be imagined that they should have equally large internal anatomy, which they do. For example, the blue whale’s heart is roughly the size of a Volkswagen Beetle and pumps about 10 tons of blood through the animal’s body.  The whale's heartbeat can be heard up to two miles off. Also, its aorta is large enough for a human to swim through. Another interesting fact about these creatures is that when they blow, also called a spout, it releases air and water that can reach thirty feet in the air.

http://wwf.panda.org/what_we_do/endangered_species/cetaceans/about/blue_whale/ http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/bluewhale.htm http://marinebio.org/species.asp?id=41 http://www.worldwildlife.org/species/blue-whale http://www.sciencedaily.com/releases/2014/09/140905090223.htm http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0098974 http://www.huffingtonpost.com/2013/09/05/blue-whale-plays-with-dolphins_n_3868061.html http://natgeotv.com.au/tv/kingdom-of-the-blue-whale/blue-whales-and-communication.aspx http://www.afsc.noaa.gov/nmml/education/cetaceans/blue.php http://www.bbc.co.uk/nature/life/Blue_Whale http://commons.wikimedia.org/wiki/Balaenoptera_musculus