[Illustration: Whale Attacked by Bloodheads.]
THE Whale family, or the Cetacea, are really aquatic animals, although
they resemble Fishes externally. Their whole structure—their lungs
instead of gills for breathing, their heart, and their manner of feeding
their young, all show that they belong to the Mammals. Only, instead of
being organized for living on land, they are better suited for the
water. Some of them reach an enormous size, and are the giants of the
animal kingdom.
Their body, more or less spindle-shaped, is terminated in a tail which
is very broad and forms a fin. This fin or tail is not vertical, as in
Fishes, and it is the principal agent for moving these living masses.
On the back of most of the Cetacea there is another fin, which is merely
a part of the skin. They have no hind fins, and their great front fins
or arms are of little use for locomotion through the water, but serve to
balance their movements.
The skin of the different members of the Whale family is generally quite
hairless, which very rarely happens in the case of other Mammalia. The
largest of other animals are small when compared with many of the
Cetacea. These great creatures swim quite rapidly, however. Because of
the air contained in their chest, and the great quantity of grease with
which their tissues are charged, and the great strength of their tail in
pushing them forward, they move easily through the waves, looking for
the Fish, Molluscs and Crustacea, which they eat in enormous quantities.
The Whale family is first divided into two classes, the Blowing Cetacea,
and the Herbiverous Cetacea. The Herbiverous class includes the Manatees
and the Duyongs who live on the weedy, shallow shores around the islands
and mouths of rivers, and feed on the sea-weed.
The class of Blowing Cetacea includes the Whale proper, the Rorquals and
the great Cachalot or Sperm Whale, in which the head constitutes in
itself one-third, or even one-half of the total length of the creature,
the Whalebone Whale; and a second division containing the Dolphin, the
Porpoise, Narwhal, etc., in which the head is in the usual proportion to
the body.