Do you like her answer?
As the sea everywhere, even down in those depths where the sun's light cannot pierce through the masses of water, is peopled by millions of creatures—every drop of water, as we might say, alive with life—I thought it a good one. A great poet has spoken of the "multitudinous seas," but whether this was in allusion to their wealth of life, or to their myriad waves, I do not know. Certainly in his time very little was known about the dwellers in the deep, deep sea, compared with what we may learn in the present day, when the sounding-line has reached the bottom of the Atlantic, and actually brought up some of the clay that forms its floor—clay which is made up of the skeletons of myriads of creatures. It was once thought that no life could exist in the ocean-depths, but we now know that life is everywhere—in air and water, upon the earth and within it, in the lowest depths of the sea, and on the highest mountain peaks, in hot and cold climates, and in the bodies of animals: all around us—earth, air, and water—teems with life.
Now let us read once more the simple words which tell us all we can really know about what is so wonderful: "And God said, Let the waters bring forth abundantly the moving creature that hath life" (or, as it may be translated, "Let the waters swarm with swarms of living souls").
We will not read farther to-day, as I want to tell you in this chapter something about life in what are called its lower forms, and we shall find that wherever we may look, every creature is perfect in itself, and perfectly suited to the life appointed to it by its Creator, and the home where He has placed it.
My children had learnt something about the two great divisions of animals, those which belong to the great Backboned Family and those which have no backbone. It is of the latter that we shall speak today. You know that a fish has a backbone, and that it is beautifully formed, for you have often seen it; but perhaps you have not noticed that a lobster, though called one of the shell-fish, is quite unlike the true Fishes: its skeleton is not inside, but outside; there are no bones within, but all the soft parts are inside, and the hard parts outside; while the body of a fish is formed on just the opposite plan. The fish is called a Vertebrate animal, because it has a backbone, made up of numbers of separate bones called vertebras. Some of us know that this word comes from the Latin, and means that which turns, because these many small bones are so beautifully jointed together as to be all perfectly moveable, so that the long bone which they form is very flexible. Some snakes have more than three hundred of these vertebræ, and you know how they can coil and twist their glittering length.
The marks of a Vertebrate animal are very easy to remember.
It must have this wonderfully jointed backbone, and also what is called the skeleton, which is a framework of bone.
A spinal cord (from which this division of animals is sometimes called the
"Chordate").
Four limbs, and red blood.
In these respects all the animals which belong to this division are alike, though in general appearance they may be as unlike each other as a horse is unlike a bird, or a crocodile unlike a herring.