80 THE HAUNTS OF LIFE 
under the skin there is a thick layer of fat or 
blubber, which serves the double purpose of 
keeping the body warm and lightening its 
weight in proportion to its size. 
The whale catches the minute animals on 
which it feeds by swimming with its mouth 
open. But it must be able to breathe atmos- 
pheric air, not air dissolved in water as a fish 
does, and the nostrils, instead of being on the 
snout as in other mammals, are far back on the 
forehead, so that breathing can go on at the 
same time as swallowing. In short, as some- 
one has said, if you took away from the whale 
all that is adaptation to its mode of life there 
would be very little of it left. 
The teeth, when there are any, have changed 
in character, but in the “right” whale they 
disappear before birth, and have been replaced 
by long horny plates frayed at the ends, which 
hang down into the mouth. There are from 
three to four hundred of these plates, which 
form the valuable ‘“ whalebone” of commerce. 
The whale swims with open mouth through 
shoals of small animals like the sea-butterflies 
and water-fleas we have spoken of, and when 
it has secured a good mouthful it shuts its jaws 
and lets the water trickle out at the sides of 
