4 The Life of the Fish 
Face of a Fish.—When we look at the sunfish from the front 
we see that it has a sort of face, not unlike that of higher animals. 
The big eyes, one on each side, stand out without eyelids, but the 
fish can move them at will, so that once in a while he seems to 
wink. There isn’t much of a nose between the eyes, but the 
mouth is very evident, and the fish opens and shuts it as 
it breathes. We soon see that it breathes water, taking it in 
through the mouth and letting it flow over the gills, and then 
out through the opening behind the gill-covers. 
How the Fish Breathes.—If we take another fish—for we shall 
not kill this one—we shall see that in its throat, behind the mouth- 
cavity, there are four rib-like bones on each side, above the 
beginning of the gullet. These are the gill-arches, and on each 
one of them there is a pair of rows of red fringes called the gills. 
Into each of these fringes runs a blood-vessel. As the water 
passes over it the oxygen it contains is absorbed through the 
skin of the gill-fringe into the blood, which thus becomes puri- 
fied. In the same manner the impurities of the blood pass out 
into the water, and go out through the gill-openings behind. 
The fish needs to breathe just as we do, though the apparatus of 
breathing is not the same. Just as the air becomes loaded with 
impurities when many people breathe it, so does the water in our 
jar or aquarium become foul if it is breathed over and over again 
by fishes. When a fish finds the water bad he comes to the sur- 
face to gulp air, but his gills are not well fitted to use undissolved 
air as a substitute for that contained in water. The rush of a 
stream through the air purifies the water, and so again does the 
growth of water plants, for these in the sunshine absorb and 
break up carbonic acid gas, and throw out oxygen into the water. 
Teeth of the Fish.—On the inner side of the gill-arch we 
find some little projections which serve as strainers to the water. 
These are called gill-rakers. In our sunfish they are short and 
thick, seeming not to amount to much but in a herring they are 
very long and numerous. 
Behind the gills, at the opening of the gullet, are some round- 
ish bones armed with short, thick teeth. These are called pharyn- 
geals. They form a sort of jaws in the throat, and they are useful 
in helping the little fish to crack shells. If we look at the mouth 
of our live fish, we shall find that when it breathes or bites it moves 
