Whales

Cetaceans are warm-blooded, air breathing mammals that can be found in all the world's oceans and even in inland rivers. Some whales are baleen whales and some are toothed whales.

Body
Whales are warm-blooded. They have thick layers of fatty blubber under the skin to help keep them warm in icy waters. Being mammals, they must surface to breathe air. However, they can hold their breath for a long time, some of them for several hours, while they dive to the deepest parts of the ocean.

When they surface to breathe, a spout of water and steam escapes from a blowhole on their heads. Baleen whales have two blowholes, while toothed whales have one. Blowholes are covered by muscle flaps to provide a water-tight seal that prevents water from entering the blowholes. Each blowhole leads to an air passage leading to the whale's throat and lungs.When they surface, whales breathe out and the burst of air and water, called a spout, can be seen about 2 kms away. The breath bursts out at up to 400 km per hour and can go as high as 5 metres. Each species has a different shaped spout.

Whales locate objects by bouncing high-pitched sounds off them and 'reading' the echoes. This is called 'echo-location'.

Whales live in groups called pods, and members communicate with each other using a wide range of sounds such as squeaks, clicks and whistles.

A whale moves its body through the water by moving its tail up and down. Whale and dolphin tails are horizontal: they go across the body. Whale tails are called flukes.
Fish tails are different from those of whales and dolphins. Their tails are vertical: they are placed in an up/down position to the body.

Whales can swim at great speed. Killer whales can reach 60 kph, some dolphins 30 kph, the large Fin Whale cruises at 22 to 26 kph. Right Whales and Grey Whales are a bit slower, with a top speed of about 11 kph.

When a whale leaps up out of the sea, it is called breaching. Sometimes its whole body clears the water completely, and then it falls on its back with a tremendous splash. This is thought to communicate its position to other whales. The splash can be heard for kilometres. If the whale falls forward instead of backward, it is called a head lunge.

Sometimes whales have their heads out of the water for a while. This is thought to be so they can see the coastline to check where they are. This is called 'spy hop'.

Whales sometimes lift their tails (each half is called a fluke) high above the water and slap them down on the surface making a tremendous splash that can be heard far away. This lets other whales know its position. Tail slapping is often aggressive behaviour. Sometimes whales slash their flukes from side to side on the surface to create turbulence.

Sometimes whales get onto a beach and cannot get back into the water. This is called stranding. On land they die because the weight of their bodies is too great.

Life Cycle
The length of time a female whale is pregnant depends on its species. A dolphin is pregnant for about 10 months, and larger whales for up to 16 months. The calf is born tail first, and as soon as the head appears, the calf is nudged to the surface to breathe. The calf suckles milk from a nipple on the mother's body. Whale milk is very rich to help the calves grow fast. This is so they grow a layer of blubber before the winter starts, or they would not survive in the cold water.

Pectoral (front) fins are frequently used to stroke the body of another whale, probably during courtship and mating. Mothers and calves also stroke one another frequently.

Baleen whales have one mate only, and live in family groups. Toothed whales live in larger groups, called pods, often with one male and a number of females and calves.

Conservation status

Most whale species are endangered and are protected. Whaling was a major industry in the past, dating back to the 12th century, for meat and many products that were made from oil, bone and other parts. By the 18th century whales were seriously threatened and the development of fast steam-powered whaling ships in the 19th century brought whales close to extinction. In the 20th century, large factory ships were built. The whaling ships could then bring dead whales to a ship to be processed instead of having to travel back to land. This meant even more whales were killed.

Today the numbers and species of whales that a country can kill are strictly limited by international agreement, and most countries have banned whaling completely.

Dolphins and other whales are often caught in the nets of commercial fishing boats and drown.

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Whales (2002). [Online], Available: www.kidcyber.com.au