"SPRING-TIDE AT GAIRLOCH, WEST ROSS--
A STUDY OF SMALL Sh.e.l.lS.
"By the way, some people know as little about spring-tides as about small sh.e.l.ls. I lately read, in a thrilling narrative of escape from drowning, "It was neap-tide, and the sea was very far out." Evidently the writer supposed that neap-tides are the very low tides, just as spring-tides are the very high ones. Of course, the truth is, that spring-tides both rise very high and fall very low; while neap-tides are the tides of least variation,--when, in short, the tides are _nipped_, and do not fall very low.[1] Once a fortnight there is a series of spring-tides, but, for reasons astronomical, some are much better than others. The half-hour of lowest recess of a first-rate spring-tide is precious to naturalists. You may chance to find them then at the edge of the sea, working, as if for dear life, under rock ledges and among seaweeds; and, wading as deep as they can, with bare arms they lift great stones from the bottom, and examine them for their living treasures. The sea in calm weather becomes very still during that half hour. When it is ended there occurs a remarkable thing, which I have never seen mentioned in books, but I think many sh.o.r.e-naturalists and bait-gatherers must know it. It is a sort of shudder of the sea, as though it awoke; there is a sudden strong _susurrus_,--the sound of that wonderful Latin word tells you its meaning,--the wash-sh of a swift little wave, breaking all along the sh.o.r.e and rising in every crevice at your feet, the first impact of a resistless power. At such a time I found myself at Gairloch, on the sh.o.r.e of Western Ross, beyond that gem of Scottish lakes, Loch Maree.
"Naturalists divide every sh.o.r.e into its upper, middle, and lower "littoral zone." I cannot write this paper without using a few hard words; _littoral zone_ just means the beach between high and low tide-marks. Those plants and animals which live in the "upper littoral"
want no more of the sea than an occasional bath, or even merely its salt spray. The middle region is inhabited by species which prefer to be half their time under water, and the lower by those which agree with being usually submerged. Below the littoral we come upon the great _laminarian zone_, the region of waving laminaria, or sea-tangle. The best view of this submarine forest is from a boat, and you may have dipped an oar at low-water among its olive-brown fronds. These are not uncovered at ordinary tides, but a low spring-tide reveals them. Changed and weird is then the aspect of the sea, and the searcher has access to what he calls the "upper laminarian." It is but little harm after all that he ever does, if we take into account the prodigality with which the sh.o.r.e is furnished with life. But should a storm rage when the spring-tide is low, the waves tear up the tangles by hundreds, and pile them, with their countless freight of living sh.e.l.ls and other creatures of G.o.d, in irretrievable ruin on the strand.
"At Gairloch I found that the rocky sh.o.r.e, while not precipitous, was yet so steep that the various zones and their subdivisions, which on a level beach may easily occupy a mile, were compressed into a very small s.p.a.ce. Every few steps in a downward scramble brought one to a new vegetation and new forms of animal life. In particular, it was obvious that innumerable molluscs of the smaller, and therefore less-known species, found shelter and food among the seaweeds that densely clothed the rocks. These molluscs seemed brought to my hand that I might look at them. It occurred to me that no sh.e.l.l-gatherer, so far as I knew, had ever made it his study to know with exactness a compact little sh.o.r.e like this, to determine all the species of those myriads of living sh.e.l.ls, to note their distribution and relative abundance, and to estimate the number of individuals.
"It was necessary first of all to devise a right method of investigation. To examine the whole sh.o.r.e was impossible and unnecessary. Plainly I must take samples. The rocks just below high-water mark were covered with a thick stubble of _lichina_, a small plant resembling the lichens of the land. Various species of minute sea-sh.e.l.ls nestled plentifully at its roots. As much of the lichina as two hands could hold was soon sc.r.a.ped from the rocks, wrapped in paper, and called Parcel No. 1. Though months pa.s.sed before I had leisure to scrutinize my prize, I may here state the result. When all the lichina and broken plates of barnacles and other _debris_ had been removed, there remained twelve hundred and twenty perfect sh.e.l.ls, which had been alive when captured; and when they were all put into a pill-box of the smallest size used by druggists, it was scarcely two-thirds full. The leading sh.e.l.l was a dwarf form of our smallest winkle, _Littorina neritodes_,--a species which may almost be said to dislike the sea, though it cannot live far from it. There were six hundred and three of this tiny winkle. Next came lasaea, a red and white bivalve (_L.
rubra_), with four hundred and thirty-nine, mostly full grown. Small as it is, you may, with care and a good lens, open its valves and count a score of young ones within, each having a sh.e.l.l like that of its parent.
Skenea (_S. planorbis_) was third, with a hundred and six sh.e.l.ls, each like a short and not quite flat coil of brown rope. But a large skenea is less than the head of a small pin, and these were all young. The rest were a few specimens of the fry of all our other British winkles, and of the common mussel. Rissoa--so named from a naturalist of Nice, M.
Risso--is a genus of humble spiral-sh.e.l.led molluscs, which feed upon decaying seaweeds. Two specks in the parcel shewed themselves under the lens, by the bands which encircled their whorls, to be the young of _Rissoa cingillus_,--the rissoa, with the little belts around it.
"It would weary the ordinary reader to go through such details in the rest of this paper. I only seek to give him a glimpse into a world of life, of whose existence he was perhaps scarcely aware.
"Parcel No. 2 was an equal quant.i.ty of a small seaweed, with a long name, _Polysiphonia fastigiata_, which fringes common wrack between tides with its thick and branching tufts. Nothing can be simpler than the process of separating thousands of sh.e.l.ls from such a handful. You put your seaweeds in a basin of cold fresh water, and all the molluscs instantly let go and fall to the bottom. When those of this parcel were dried, the little pill-box was again in requisition; they exactly filled it. If anybody wants precision, there were forty-two minims of sh.e.l.ls.
It may give a new thought to some one to read that there were in that box about twelve thousand five hundred sh.e.l.ls, each of them a marvel of beauty, and each of them only the external skeleton of a highly organised creature, which secreted and built up that sh.e.l.l bit by bit as its soft body grew larger, and which mixed in the colours and lined it with mother-of-pearl. The little skenea, which began to appear in our first parcel, reached here the extraordinary development of about eleven thousand eight hundred specimens, of which one hundred and thirty-eight were grown up, while all the rest, to the una.s.sisted eye, were like dust, and weighed only eleven and a half grains. The remainder of the parcel consisted of twelve species, ranging in number of examples from one to three hundred and fifty. The sh.e.l.l of which there was but a single specimen was _Cyamium minutum_, a glittering bivalve, somewhat smaller than lasaea.
"Parcel No. 3 was made up by sc.r.a.ping from the rock a small strong-smelling seaweed called _Laurencia_, which grows near low-water.
It yielded about twenty thousand sh.e.l.ls, belonging to fourteen species, and they more than filled two of the little boxes. The most remarkable circ.u.mstance was, that the shining little bivalve cyamium, which was represented by a solitary specimen in the second parcel, formed here at least three-fifths of the whole. In other words, twelve thousand individuals, old, young, and middle-aged, of this cyamium--each of them a good walker, a good swimmer, a good spinner when it wished to moor itself by a rope, and each the maker of its own polished sh.e.l.l--were cl.u.s.tered upon a handful of one of their favourite plants. I could not get them till now, because I was not near enough to the edge of the ebb tide. It may be worth noting that there are other sh.e.l.l-gatherers who know where to look for cyamium, for it is told in books upon sh.e.l.ls that thirty-five thousand cyamiums were once taken from the stomach of a mullet.
"No. 4 was a parcel of the same size as all the rest, and consisted of various small seaweeds growing at ordinary low water. It proved to contain about eight thousand five hundred sh.e.l.ls, of ten species. There was scarcely a bivalve among them. Two _lacunae_ (cousins to the winkles), and a pearly top-sh.e.l.l (_Trochus helicinus_), shewed by their abundance that the verge of the accessible sh.o.r.e was nearly reached.
"No. 5 was a parcel of the same kind, from the lowest point of the spring-tide, and produced about thirteen thousand sh.e.l.ls. The between-tides species--such as skenea--now visibly began to fail, and a few sh.e.l.ls from deeper water, including a youthful scallop, made their appearance.
"The tide was about to turn. Could one more "parcel" be achieved? From the rock there was visible, far down in the quiet depth, a giant frond of laminaria, apparently detached, but likely still to have its sh.e.l.ly inhabitants upon it. The day was warm, the spot retired, the water inviting; to swim downwards with the eyes open is easy, if you learned as a boy. Soon the laminaria was gently laid on dry rock. It was quite ten feet long, and bore one hundred and fifty-seven little sh.e.l.ls of nine species, one of them a prize--_Rissoa violacea_.
"This record is not written for conchologists, but for others to whom its facts are unfamiliar or unknown. Two dozen species, most of them common, and three or four varieties, were all that were found. But, of individual sh.e.l.ls there were fifty-five thousand. A calculation, necessarily rough, but as likely to be under the truth as over it, led to the conclusion that, if it were possible to examine all the seaweeds which the lowest tide leaves bare for a stretch of only twenty-five or thirty yards along that sh.o.r.e, a hundred million living sh.e.l.l-bearing molluscs would be found. Of all these not even the smallest would, strictly speaking, be a microscopic object, though certainly requiring a lens for the determination of its species. A hundred millions! How easily we set down the words! And neither the writer nor anybody else has the least conception of what they represent. And if, from that little nook on the Gairloch as a measured base, I tried to estimate the molluscan population of our British sh.o.r.es, making due allowance for the comparative barrenness of many places, I might fill a large part of one of these lines with figures; but who would be any the wiser?
"We are not to suppose that a sh.o.r.e so prolific as that of Gairloch has really only twenty-four kinds of sh.e.l.ls. That no more were found among the seaweeds examined, is simply due to the circ.u.mstance that all the samples were taken from the same kind of ground. Hard by, round a jutting rock, there is a sandy sh.e.l.l-strewn beach on which, without trouble, fifty species may be gathered,--some of them such rarities that the reading of their names is enough to make an eager collector wish he might forthwith take train for Achnasheen.[2] Let us single out one.
Time was when _Crenella decussata_ was known to naturalists by a single valve. Here, in a little sh.e.l.l-sand, were six perfect specimens, the valves united and closed, or each what children call a "box." Imagine an almost transparent pearl, the size of a grain of mustard seed, suffused with opaline gleams, and covered with exquisite latticed and bead-like sculpture. It wants nothing but size to rival the most splendid exotics.
"Nothing but size! But, to most people, size is everything; wherefore to them the small sh.e.l.ls and their beauty are not. Their minuteness hides them as though they were in a far-off and uninhabited isle. To science bulk is an accident, only one of the many properties which she has to consider. What science does for us--even for those of us who, being otherwise busy, can be naturalists only in our leisure time--is something still more important than providing us with a magnifying lens.
She takes away that mental habitude which makes minuteness a barrier to interest,--she puts her hand on the inward eye, and we see. Whosoever has been thus _touched_, has an "open-sesame" to a treasure-house, has a slave of the lamp to make rubies common. And, besides all this, who dare say that that hidden world of beauty and adaptation is wasted, is lost, till the scientific observer draws near? Certainly he who has watched the little molluscs at their love and their play will be slow to think that they have not a sense of beauty which can be pleased. He who notes how the sh.e.l.ls during life are protected from their enemies by their colours; how they are brown and yellow and red like the seaweed on which they feed; how they are pink and white among those algae which are encrusted with lime; how they are transparent and iridescent as any jelly-fish in the clear sea-water,--has a glimpse into the process by which the Divine Architect who works through the ages fashioned those manifold species. And I, for one, am of Charles Kingsley"s creed in this matter:--"See now," said the hero of "Westward Ho!" to his brother, as they looked at flies and flowers and humming-birds in a West Indian island, uninhabited till the white man came,--"See now, G.o.d made all these things, and never a man, perhaps, set eyes on them till fifty years agone; and yet they were as pretty as they are now, ever since the making of the world. And why do you think G.o.d could have put them here, then, but to please Himself"--and Amyas took off his hat--"with the sight of them?""
APPENDIX.
Mr Dixon has kindly sent me a considerable quant.i.ty of sh.e.l.l-sand from Gairloch sh.o.r.e. I have examined it, and found the following sea-sh.e.l.ls. Those which were somewhat plentiful are marked with an asterisk. It would be easy to name some additional sh.e.l.ls which will probably be found on Gairloch sh.o.r.e, though they were absent from the sand examined; but I have preferred not to do so.
*Anomia ephippium.
* Do. do., _var._ imbricata.
*Pecten opercularis.
P. similis (a valve).
*Mytilus edulis.
*Modiolaria discors.
*Crenella decussata.
*Montacuta ferruginosa (single valves).
M. bidentata.
Kellia suborbiculata.
*Cyamium minutum.
*Cardium edule.
*C. nodosum.
C. echinatum.
C. Norvegic.u.m.
*Cyprina Islandica.
Astarte sulcata (a valve).
A. triangularis.
*Venus gallina.
V. lincta.
V. exoleta.
*V. casina.
V. ovata (a valve).
*Tapes virgineus.
Do. do., _var._ alba.
*Tellina tenuis.
*T. fabula.
T. pusilla.
*Psammobia ferroensis.
*Donax vittatus.
*Mactra stultorum.
Do. do., _var._ cinerea.
M. subtruncata.
M. solida.
Scrobicularia prismatica.
*Solen siliqua.
*Thracia papyracea.
*Saxicava rugosa.
* Do. do., _var._ arctica.
* Do. do., _var._ minuta.
*Patella vulgata.
* Do. do., _var._ picta.
* Do. do., _var._ crulea.
*Helcion pellucidum.
* Do. do., _var._ laevis.
Tectura testudinalis.
*T. virginea.
*Trochus cinerarius.
T. umbilicatus.
*T. millegra.n.u.s (young sh.e.l.ls).
*T. helicinus.
*Do. do., _var._ fasciata.
T. zizyphinus.
*Lacuna divaricata.
*L. pallidula.
*Littorina obtusata.