DENIZENS OF THE SEA:
CETACEANS – I
One of my most memorable vacations was spent in the cozy confines of my mother’s home at Kolkata. One such lazy winter afternoon saw my young five year old son and me exploring the various facets that Kolkata’s Science City had to offer. A visit to the local amphitheatre left us ogling at the marvelous world of Cetaceans It is indeed intriguing to know that the oceans provide more than hundred times more living space than land and teem with forms of life that range from single-celled micro-organisms to gigantic aquatic
mammals.
Giving a thought to aquatic communities, our minds can almost visualize a mammoth blue whale splashing across calm blue oceanic waters.
Whales belong to the family of ‘cetaceans’. The word ‘cetacean’ means a large sea
animal. Though they resemble fish, they are mammals and are often extremely intelligent and somewhat social.
Scientists have classified whales into
baleen whales and
toothed whales. Baleen whales are often called ‘mysticeti’ which translates literally to mustached whales and are the largest animals to inhabit the earth. Some of these are said to be larger in size than the dinosaurs that walked the earth centuries and centuries ago. The endangered species of the blue
whale is a baleen whale.
The baleen whale is very different from its distant cousin, the toothed whale. Toothed whales are also known as ‘odontoceti’ which means whales with teeth. Dolphins and porpoises are well known whales in this category.
Repetitive studies on the bodies of whales show that though they inhabit the water-world, their roots are firmly in land. It is particularly astonishing to note that whales are closely related to hoofed animals, particularly cattle and deer. Scientists have reason to believe that whales began to develop about 70 million years ago. However, the oldest whale fossil is about 45 million years old.
Over a period of time, the front legs of whales have metamorphosized into flippers, which have the bones of a five-fingered hand. The bodies of some whales house the bones of hind legs but most of the whales have only two tiny hip bones. In contrast to fish, whales are warm blooded. Their body temperature remains the same irrespective of the temperature of their environment.
Down the ages whales have gradually lost some of the characteristics of mammals. Hair covers the bodies of most mammals but whales have only a few stiff hairs in the head. It is apparent even to the casual observer that hair probably has scant use to an animal that lives mainly in a submerged state.
Whales have many special characteristics suited to under-water life. A land animal stops growing before its bones and muscles can no longer support its body weight. The buoyancy lift of water helps support a whale’s body and makes it possible for whales to grow larger than any land animal.
Swapna Datta Khan
Faculty, ICFAI, India
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