Whales - Cetaceans

[Astronuc]

Fascinating creatures are these mammals that live in the sea.

The term whale is ambiguous: it can refer to all cetaceans, to just the larger ones, or only to members of particular families within the order Cetacea. The last definition is the one followed here. Whales are those cetaceans which are neither dolphins (i.e. members of the families Delphinidae or Platanistoidea) nor porpoises. This can lead to some confusion because Orcas ("Killer Whales") and Pilot Whales have "whale" in their name, but they are dolphins for the purpose of classification.

http://en.wikipedia.org/wiki/Whale

The largest of course is the Blue Whale which can grow over 100 feet and weigh as much as 140 tonnes. http://en.wikipedia.org/wiki/Blue_Whales  It is one of the baleen whales - http://en.wikipedia.org/wiki/Baleen_whale.

The sperm whale (http://en.wikipedia.org/wiki/Sperm_Whale) is the largest of the toothed whales - http://en.wikipedia.org/wiki/Toothed_whale.

In a Nantucket museum there is a jawbone of a sperm whale which is 5.5 m (18 ft). The jawbone makes up to 20%-25% of the sperm whale's overall body length. Thus this whale might have been 28 m (90 ft) long, weighing around 150 metric tons (165 short tons). Another evidence of large bulls of the past resides in New Bedford museum, a 5.2 metres (17 feet) jaw of a bull that could have been about 25.6 metres (84 feet) long, weighing about 120-130 tons. In addition, log books found in the Nantucket and Bedford museums are filled with references to bulls that were, considering the amount of oil they yielded, about the same size as these two examples. Today, Sperm Whale males do not usually exceed 18 m (60 feet) in length and 52 metric tons (57 short tons) in weight.

In 1820, a sperm whale estimated to be about 25.9 m (85 ft) long attacked a Nantucket whaling ship Essex. Only 8 out of the 20 sailors managed to survive and be rescued by other ships.

[Astronuc]

Someone asked the experts through Scientific American - "How do deep-diving sea creatures withstand huge pressure changes?"

Paul J. Ponganis and Gerald L. Kooyman of the Center for Marine Biotechnology and Biomedicine at Scripps Institution of Oceanography provide the following answer.
http://www.sciam.com/askexpert_question.cfm?articleID=0004B545-8D8D-1CD1-B4A8809EC588EEDF&catID=3

From the days of whaling, these animals have been recognized as exceptional divers, with reports of dives lasting as long as two hours after they were harpooned. Today, with the use of sonar tracking and attached time-depth recorders, dives as deep as 6,000 feet (more than a mile below the surface of the ocean) have been measured. Routine dive depths are usually in the 1,500- to 3,000-foot range, and dives can last between 20 minutes and an hour.

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Another organ susceptible to compression damage is the lung. In deep-diving whales and seals, the peripheral airways are reinforced, and it is postulated that this allows the lungs to collapse during travel to depth. Such collapse has been observed radiographically and confirmed with blood nitrogen analyses in the deep-diving Weddell seal.

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Loss of gas exchange at depth has another important implication: the lungs of the deep diver cannot serve as a source of oxygen during the dive. Instead deep-diving whales and seals rely on large oxygen stores in their blood and muscle. Several adaptations enable this. First, these animals have mass specific blood volumes that are three to four times those found in terrestrial mammals (i.e., 200 to 250 milliliters of blood per kilogram body mass, in contrast to a human value of 70 milliliters blood per kilogram). Second, the concentration of hemoglobin (the oxygen-transport protein in blood) is also elevated to a level about twice that found in humans. Third, the concentration of myoglobin, the oxygen storage protein in muscle, is extremely elevated in these animals, measuring about 10 times that in human muscle.

Remarkable creatures!