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Whales
What are they?
Whales are those gigantic sea mammals, that look like fishes, but are not. They are mammals. Other sea mammals include dolphins, for example. Whales form a group of mammals called cetaceans. This is from Latin and means giant sea animals. They are divided into two groups -
How do they live?
The whales are huge creatures ( atleast most are ). The blue whale is the largest animal that ever lived, and can cover 30 metres and weigh over 130 metric tones. Yes, there are smaller ones.
The whale has the shape of a fish ( bullet like or streamlined ). The basic
external difference is that the
tail is horizontal, not a vertical one like other fish.
Internally, they differ from fish on the basis that they have lungs, not gills.
The sperm whale, can hold it's breadth for 2 hours.
The other whales too can hold air for long periods of time. Like all mammals (
with the exception of monotremes - those that lay eggs ), they give birth to live
young ones. Whales are warm blooded. They do have hair, even if they are on the
verge of becoming hairless. They have fins, not legs. The only consolation to
the whale for this is that there are two tiny hipbones for the hind legs.
Kinds of baleen whales
Baleen whales possess no teeth. To make up for this, they have plates in their
mouth. The material is that of finger nails. These feed on plankton, mainly.
They are divided into :
Right whales have a thick body and a huge head. The head of most whales forms about one third of the entire body weight. They swim slowly. They feed by going into a group of plankton, with wide open mouths ( probably indicating that they are hungry ).
Rorquals are those that have grooves on the chest.These enable it to open it's mouth wide, taking in more food and water, and then push out the water through the baleen's. They lung forward to meet their prey. They all have a back find, and are also known as finback whale. They are streamlined, and hence can swim faster. There are six rorquals, but I will talk of only the first one - the blue whale. The other five are the fin whales, mink whales, Bryde's whale, sei whales and the humpback whale.
Blue whales are the largest animal that ever lived. They can grow upto 30 metres, and weigh 130 metric tones, if not more. They are blue-gray-white, but they appear evenly blue under water. They live in all oceans, but are endangered. They feed on shrimp like animals.
The third kind of toothless whales are the gray whales. The skin of these whales is gray. They live in North Pacific. They have white blotches. They also provide a ride to other white blotches, or rather another animal - barnacles. They have lower humps on the lower back. They can grow more than 10 metres. They live on the sea floor. They take in the sand, and throw it out, keeping only the animals that were there.
Toothed whales
These whales have teeth and are grouped into 5 groups. There are 65 members of this group. They differ in many aspects. They eat fish and squid mainly but can also eat octopus, cuttlefish, crab etc.
The divisions are as follows -
It may be hard to believe that dolphins as whales. But they have features of the tooth whales.
Sperm is the largest of the lot. They can grow till 15 metres, if not more. They have square shaped heads. It forms about one third of the total body length. They have 18 to 25 small teeth. The teeth of the lower jaw fit into the toothless upper jaw.
Beaked whales have a beak like mouth and only 2 to 4 teeth in the lower jaw, and generally no teeth in the upper one. Some have small beaks, while other large. There are 18 species of beaked whales. They feed mainly on fish, squid and live in deep waters.
The Belugs and Narwhals are around 5 metres long. The narwhals are usually found in Arctic, but Belugs are found further south and are fully white when fully grown. The narwhals and belugs eat fish, squid , shrimp, crab. The belugs have around 30 to 40 teeth. The narwhals are gray on top and white below and have brown spots all over them. They have two teeth. The teeth of a female remains in the upper jaw - buried. The males, the left one develops into a spiral tusk.
Dolphins and porpoises live in all oceans. The latter grows upto 2 metres. The dolphins can grow till 9 metres. They include killer whales. The river species are found in rivers like the amazon, the Ganges, the Indus. They grow upto 2 metres and have long beaks and poor eyesight.
