A STARFISH AND A DAISY
Day after day the forms of horses, dogs, birds, and other creatures pass before our eyes. We look at them and call them by the names which we have given them, and yet—we see them not. That is to say, we say that they have a head, a tail; they run or fly; they are of one colour beneath, another above, but beyond these bare meaningless facts most of us never go.
Let us think of the meaning of form. Take, for example, a flower—a daisy. Now, if we could imagine such an impossible thing as that a daisy blossom should leave its place of growth, creep down the stem and go wandering off through the grass, soon something would probably happen to its shape. It would perhaps get in the habit of creeping with some one ray always in front, and the friction of the grass stems on either side would soon wear and fray the ends of the side rays, while those behind might grow longer and longer. If we further suppose that this strange daisy flower did not like the water, the rays in front might be of service in warning it to turn aside. When their tips touched the surface and were wet by the water of some pool, the ambulatory blossom would draw back and start out in a new direction. Thus a theoretical head (with the beginnings of the organs of sense), and a long-drawn-out tail, would have their origin.
Such a remarkable simile is not as fanciful as it might at first appear; for although we know of no blossom which so sets at naught the sedentary life of the vegetable kingdom, yet among certain of the animals which live their lives beneath the waves of the sea a very similar thing occurs.
Many miles inland, even on high mountains, we may sometimes see thousands of little joints, or bead-like forms, imbedded in great rocky cliffs. They have been given the name of St. Cuthbert’s beads. Occasionally in the vicinity of these fossils—for such they are—are found impressions of a graceful, flower-like head, with many delicately divided petals, fixed forever in the hard relief of stone. The name of stone lilies has been applied to them. The beads were once strung together in the form of a long stem, and at the top the strangely beautiful animal-lily nodded its head in the currents of some deep sea, which in the long ago of the earth’s age covered the land—millions of years before the first man or beast or bird drew breath.
It was for a long time supposed that these wonderful creatures were extinct, but dredges have brought up from the dark depths of the sea actual living stone lilies, or crinoids, this being their real name. Few of us will probably ever have an opportunity of studying a crinoid alive, although in our museums we may see them preserved in glass jars. That, however, detracts nothing from the marvel of their history and relationship. They send root-like organs deep into the mud, where they coil about some shell and there cling fast. Then the stem grows tall and slender, and upon the summit blooms or is developed the animal-flower. Its nourishment is not drawn from the roots and the air, as is that of the daisy, but is provided by the tiny creatures which swim to its tentacles, or are borne thither by the ocean currents. Some of these crinoids, as if impatient of their plant-like life and asserting their animal kinship, at last tear themselves free from their stem and float off, turn over, and thereafter live happily upon the bottom of the sea, roaming where they will, creeping slowly along and fulfilling the destiny of our imaginary daisy.
And here a comparison comes suddenly to mind. How like to a many-rayed starfish is our creeping crinoid! Few of us, unless we had studies about these creatures, could distinguish between a crinoid and one of the frisky little dancing stars, or serpent stars, which are so common in the rocky caves along our coast. This relationship is no less real than apparent. The hard-skinned “five finger,” or common starfish, which we may pick up on any beach, while it never grew upon a stem, yet still preserves the radial symmetry of its stalked ancestors. Pick up your starfish, carry it to the nearest field, and pluck a daisy close to the head. How interesting the comparison becomes, now that the knowledge of its meaning is plain. Anything which grows fast upon a single immovable stem tends to grow equally in all directions. We need not stop here, for we may include sea anemones and corals, those most marvellously coloured flowers of the sea, which grow upon a short, thick stalk and send out their tentacles equally in all directions. And many of the jelly-fish which throb along close beneath the surface swells were in their youth each a section of a pile of saucer-like individuals, which were fastened by a single stalk to some shell or piece of coral.
We will remember that it was suggested that the theoretical daisy would soon alter its shape after it entered upon active life. This is plainly seen in the starfish, although at first glance the creature seems as radially symmetrical as a wheel. But at one side of the body, between two of the arms, is a tiny perforated plate, serving to strain the water which enters the body, and thus the circular tendency is broken, and a beginning made toward right and left handedness. In certain sea-urchins, which are really starfishes with the gaps between the arms filled up, the body is elongated, and thus the head and tail conditions of all animals higher in the scale of life are represented.