Blue Whale
Which class do they classify in?
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Balaenopteridae
Genus: Balaenoptera
Species: musculus
What is their scientific name?
Blue whales also have their own scientific name. Scientists named them as Balaenoptera musculus. They are marine mammals and they belong to suborder of baleen whales.
Where do they live?
Blue whales live in all of the world's oceans. There are three subspecies. Those found in Canada belong to the northern hemisphere subspecies—of which there are both north Atlantic and north Pacific populations. The Atlantic population of blue whales frequents waters off eastern Canada: along the north shore of the Gulf of St. Lawrence; off eastern Nova Scotia; off the south coast of the island of Newfoundland, in the Davis Strait between Baffin Island and Greenland. While they usually go south in winter, some do linger in the St. Lawrence and off southern Newfoundland during years of light ice cover.
What reasons that cause blue whales in a big size?
For Scientists, they are sure of one thing- there is no other living animals as big as the blue whale if compared with the ancient dinosaurs. The blue whale is the largest creature to have ever lived on earth! One of the most important reasons that causes whales to have its larger size is they have more space to grow in the natural. This is because over 70% of the Earth is covered in the ocean water. Another reason about living in the oceans, besides all the real estate, is the weightlessness effect of water or in other words we can call it under water pressure. For example, if you like to swim or scuba dive, you will know how it feels to be in the water. The feeling almost like floating in space. (In fact, NASA sometimes trains their astronauts inside huge tanks of water to get familiar with working in a zero-gravity environment.) It's the weightlessness of the ocean environment that allows a whale to maintain such huge proportions. Instead of relying on a skeleton to support the weight of its massive bulk the buoyancy of the surrounding ocean water supports the weight of the whale's body tissues. If a blue whale were to be taken out from the ocean, it would smother under its own weight due to the effects of gravity.
What do they look like?
No other marine animals which have the largest size if compare with blue whale on Earth today and the largest known to have ever existed. The blue whale is a rorqual whale—one of a group that has pleats in its skin of its neck which allow it to expand its mouth to take in huge volumes of water while feeding. One quarter of its entire length is made up by its head. It has a smallish dorsal fin and pointed pectoral flippers. Despite its name, the blue whale is blue-gray in colour, often with lighter gray mottling on a dark background or with dark spots on a light background; every whale has a unique pattern of mottling that makes it identifiable. The blue whale isn't just big and it is also can produces loud voice. It can emit sounds at up to 186 decibels—louder than a large ship at 100 meters distance away from the seashore. These sounds are produce in a low pitch that below the normal range of human hearing. To date, researchers have not been able to determine why the whales make these calls, although it is likely for communication.
What do they eat?
Blue whales eat mostly krill (shrimp-like crustaceans about two centimetres long). A single blue whale can consume as much as four tons in a day. During feeding, large volumes of water and food are taken into the mouth and the pleated grooves in the throat expand enormously. As the mouth closes, water is expelled through the baleen plates, which trap the food inside near the tongue to be swallowed. They force the water back out by using their baleen as filters to catch the krill and planktonic organisms that were in the water.
What is their life cycle?
Living between 70 and 80 years, blue whales reproduce every two or three years. Females give birth every 2-3 years with the gestation lasting about one year. At birth, the calf is about 25 feet long and will weigh about 3 tons. When you think about this information, this newborn baby is already ranking among the largest animals on Earth. The largest adult on record measured 29.5 metres; like other rorquals whales, females are larger than males. Calf will consume only its mother's milk, up to 100 gallons a day. Until they are weaned at 7-8 months of age, they will stop feeding milk by their mother. Female’s milk is rich in fat which allows her calf to gain about 200 pounds a day (about 8 pounds an hour). Besides, blue whales will reach sexual maturity when they are about 6-10 years of age. For your information, the total number of blue whales in the Atlantic population is unknown, but as many as 105 are spotted annually in the Gulf of St. Lawrence. Overall, since in the year of 1979, 382 individuals have been recorded in the Gulf and it is just under half return regularly. Blue whales travel singly or in small groups. They might be migrating between temperate waters in summer and more tropical waters in winter. They can swim at speeds of up to 36 kilometres per hours, but typically cruise between two and eight km/h.
IT’S EXTINCTION
Why is it at risk?
At least 11,000 blue whales were hunted and killed in the north Atlantic prior to 1960. Approximately 1,500 of blue whales were taken in eastern Canadian waters. Despite the end of commercial hunting in Canada, blue whales remain threatened by human activity in this country. The incidents happened like examples collisions with ships, entanglement in fishing gear, and the effects of pollution which all have the potential to harm these giant creatures on Earth.
What is being done?
Species at Risk Act (SARA) is an organisation protected the blue whale which is listed as endangered and protected. It is also protected under Canadian Whaling Regulations, which prohibit commercial hunting within Canada's 200-mile fishing zone. Internationally, blue whales are protected by the International Whaling Commission. Meanwhile, the blue whale is also listed by both the World Conservation Union (IUCN) and the Convention on the International Trade of Endangered Species (CITES). A recovery plan is in development for the blue whale where this species will get the protection. It is needed only if all Canadians work together to reduce threats toward the blue whales. Find out more and do your best to reduce these threats wherever possible to better protect its critical habitat. Get involved with the Habitat Stewardship Program for Species at Risk (HSP), or other conservation organisat
REFERENCE.
1. BBC.co.uk/news.
2. http://library.thinkquest.org/J0112630/blue_.htm-Blair Elementary School, 1000 Fairchild Hwy., Fairchild AFB, WA 99011, mhendri@mlsd.org
3. http://www.suite101.com/article.cfm/arctic_wildlife/106362
Author: Fred J. Kane Feb 10, 2004
看着这背影，，多孤独啊。。
