whale is Earth's largest animal. Larger than the largest of ancient
dinosaurs, blue whales can grow to be more than 100 feet (30 meters) long
and weigh nearly 150 tons. Not all whales are so large. The much smaller
pilot whale grows to about 28 feet (8.5 meters) in length. And dolphins,
which belong to the whale family, range only from 3 to 13 feet (1 to 4
meters). Although whales spend their lives in the sea, they are, like
humans, warm-blooded mammals. After a baby whale is born, it nurses on its
mother's milk, just like the young of land mammals.
Whales are members of the order Cetacea, along with dolphins, porpoises, and
the narwhal. There are …show more content…
of both northern and southern seas. Scientists believe that those in the
western North Atlantic may be gradually increasing in numbers. However,
populations in the eastern North Atlantic and in both the eastern and
western North Pacific show no signs of recovery, and only a few remain in
each area. An estimated 1,500 to 3,000 occur in the southern oceans, with
little evidence of a significant increase in population sizes in most areas.
Some scientists place the southern right whale in a separate species: E.
australis. Black right whales reach lengths of 70 feet (21 meters) and are
black on the upper body. The underside is sometimes paler in color. The
baleen plates in the mouth may be more than 8 feet (2.4 meters) long.
The toothed whales include more than 65 species in six different families.
Among these are the true dolphins (family Delphinidae), which includes the
pilot whales (genus Globicephala) and the killer whale (Orcinus orca),
largest of the oceanic dolphins. Killer whales prefer coastal waters to the
open ocean. They hunt in schools and, though relatively small at 30 feet (9
meters), will attack other whales two or three times their size.
Two other families include the true porpoises (Phocoenidae), which are
marine species, and the river dolphins (Platanistidae), consisting of six