A Motherly Knight in Armor, Page 2

We require a seahorse, so from Nonsuch we send out a motor boat and pull a small dredge slowly through some of the growth of eel-grass in Castle Harbor. One, two, three or no seahorses may result, but usually we find at least one of the curious little beings lying quietly in the mass of trigger-fish, shells, grass, seaweed, and mud. He is as helpless as a prostrate knight in armor. I lift him and gently wash the mud out of his fin-mane I was going to say and then let him slide down the sub-merged ways of my fingers and he is launched in a fresh aquarium. He rights himself not like other fish, but vertically, turns his eyes from left to right, and glides slowly away. He seems to have no visible power of propulsion, but it is the invisibility of an airplane propeller the fin on the back has become a dim, thin haze, its endless rippling web pushing back against the resisting water. The aquarium is a narrow rectangle and the seahorse traverses one long side, then a short end, and rests. And this first journey drives home a simile that needed just such an impetus; much more than the head of a horse, our Hippocampus resembles the knight of the chessboard, and his first move in the aquarium has been a knight's move two squares ahead and one to the right.

It is well, however, to get rid of the horse idea altogether and watch and learn to like our fish for himself. I put in a branch of seaweed and the long tail feels for it and coils about it with the grip of a chameleon. The next person who comes up to look cannot at first find the seahorse he has begun to lose his identity. As we watch, this continues he shifts from dusky brown to a pale neutral color and then again to dark, this time green, and Hippocampus is fairly within the protective cloak of seaweed sanctuary. He has gone vegetable and has taken upon himself the easy load of seaweed dangers and the very considerable advantage of algal immunity. I reach down and gently swing the weed back and forth, and still another trick is sprung the little creature sways both body and head loosely to and fro in rhythm with what to him are the swells of ocean. On die tips of the knobs and spines of his armor are numerous, long bits of frayed out filaments and these wave about and importantly disguise his zoological reality.

So here we have the seahorse and his niche in the world, balanced and weighed in the scales of life and death and found on the whole good. From snout to tail he is encased in bony jointed rings one ring to each backbone, and while it slows him down almost to snail pace, yet it serves to protect him from small predaceous crabs and other enemies. To carry about such a complete armor requires delicate adjustments, one of which is a large swim-bladder filled with gas just sufficiently buoyant to hold him in hydrostatic equilibrium. If, through accident, his inner balloon is punctured and the merest pinpoint of a gas bubble escapes, gravity seizes upon him, he sinks helpless to the bottom, there to remain until his wound be mended, or until Nemesis comes along on legs or fins.

Even for the seahorse in perfect health and strength there are waiting scores of hungry mouths armed with great cruel teeth that would crush him like a nut. Against these he builds up the sea-weed defense of haunt, color, pattern, shape, movement, and in addition he even has an unpleasant odor or to water creatures, taste. His tail fin most valuable of all for progression is gone and instead he twines like a tendril. His life is lived at lowest output of energy, a semi-sessile pseudocrinoid of sorts, almost, we might think, on the way to the fixation of barnacles. But this is not degeneration, it is adaptation to a safe environment, and as we go on to study Hippocampus we realize that he need have no envy for the swift herring or the voracious dolphin.

It would seem that in the matter of food our seahorse must desert the quiet, patient elementalness of seaweed, and dangerously revert to fish activity. But here again Nature has worked out a most ingenious plan. For such a vegetative existence little nourishment can be needed, yet we have a carnivore that must have food. Resting on a frond of weed in the aquarium is a tiny crustacean, one of the untold myriads that inhabit all the seas in the world. The seahorse has also seen the copepod, but he wishes to keep me under surveillance as well. Slowly he swims nearer and nearer, and peers ahead with the comic intensity peculiar to short-sightedness. He turns sideways, and now the approach is still slower and he accomplishes two things simultaneously one eye is cocked forward, gazing steadily at his victim, the other is twisted far back, never leaving our person. It was fair disconcerting and rather disturbed my own concentration. He throttled down his little push propeller to lowest speed, and the slowness of his advance began to approach the rapidity of the growth of his seaweed. Then he went into reverse, with no change that I could detect in fin ripples, and I looked and found that the copepod had vanished. I was certain that it had not swum away, the seahorse had made no snap or bite in its direction, and I was completely confused.