The whales indicate ( or rather their bodies do ) that they are relatives of the hoofed mammals, especially the ones with split hooves.. Some believe that they developed from meat eating mammals. The oldest fossil dates to 50 million years.

Whales have bodies that are designed for aquatic life.By living in water, their body size increases. A land animal can grow only till it's legs are suited to carry the weight, but the water provides buoyancy.

Body shape - Whales have a streamlined body, enabling them to swim with least resistance. Their tails go up-down, instead of right-left found in other fish.

The ancestors lived on land, and had four legs, but they lost them when they moved in water - over millions of years. They turned into flippers. They use their flippers to steer and maintain balance.

The skeleton of a whale resembles mammals. They lack hind legs though, but have two small muscles.

They have their vertebrae compressed into a short span, or fused into a bone. This keeps the head from moving while swimming. It joins the head to the body, helping in it's streamlined shape.

Whales have smooth skins, and slip through the water. They are not covered with hair, though and have but few on their head. Beneath this skin, blubber is found. This keeps them warm. But sometimes this proves oppressive. The rorquals have blubber only till 15 cm. This is more in other whales, like the right ones having upto 40 to 50 cm of blubber. The whales can live of their blubber for a long time. Large baleen whales feed very little - about 8 months, during migration. Blubber helps whales float.

They breathe through lungs. They come to the surface for water. They can stay quite a long time, with just one breath. There is a reason for this. Their muscles store more air in them than of any other mammal.

Humans store 13 percent, but whale's hold 40 percent. During a dive, they reduce the blood flow to muscles, but to the other parts, it is the same ( heart, brain ). Also the heart beat slows down, helping in save oxygen. After a dive, a whale takes several breadths to recharge oxygen. They have a blow hole at the top of their head. But as it breaks through the water, it has only 2 seconds to let out air and take in more. Upon exhalation, a whale produces a cloud. The exhaled air consists of water vapour and air with little amounts of oxygen.

Most whales reproduce at a season. The male ( bull ) and female ( cow ), mate. During courting they stroke each other with flippers. One bull may mate with several cows during a season. Jostling occurs between males.

The period of pregnancy last 10 months to a year. A sperm whale carries the baby for 14 months. Usually, there is only one baby called a calf ( big surprise ! ) The newborns are huge, weighing a bit below 2 metric tons, and is above 5 metres in length. As it is born, the mother nudges it to take it's first breadth.

Whales ( the mothers ) are protective of their young, staying with them for upto a year. They nurse their young. They have a special muscle, to pump milk into the young. The food is rich with nutrients, and helps the young grow fast. Blue whales ( babies ) gain upto 90 kilograms a day. The young blue whales and fin whales are nursed till 7 months. The others generally nurse to a year. Sperm whales and Pilot whales may nurse upto 3 years.

Whale's live in herds. The toothed ones are generally more organized compared to their toothless counterparts. Many species of dolphins travell in herds of 1000 or more.

Most toothless whales live alone or in small groups. Young stay with the mother for a year or less.

They can communicate over large distances. They can produce sounds that are low pitched The whales can hear sound for a very large distance. The best known sounds belong to a humpback whale. They make a sound lasting for upto 15 to 20 minutes and than repeat it.

Most baleen whales migrate between the polar and tropics. The cold polar water is rich with plankton. They spend their summer hear, store blubber and with the arrival of winter, move to warmer water, where they mate and provide a comfortable environment for the young. In tropics, adults

Two kinds of baleen whales do not migrate. Some Bryde's whales live in the tropics all the year round, and bowhead whales never leave the Arctic. Most species of toothed whales also do not migrate. Belugas and narwhals stay in Arctic waters. Most sperm whales live only in tropical or temperate seas. Older, larger males spend the summer in polar waters.

The whales live their life, though some have them long ( 60 years ) while some short ( 15 years ) lives. The killer whales and Sperm whales live longer lives. Humans and sharks are responsible for the death of whales .Killer whales and Dolphins attack smaller whales and dolphins. A very sad form of death of whales is when they swim away, towards the sea shore. When low tide occurs, they get stranded. Since they always need their skin to be wet, they die a dehydrated death. Usually, people help them return, but sometimes, they die.