CHAPTER XII

THE PLANTS OF THE SEA AND THEIR USES

The ocean was the home of the first living thing, either plant or animal, that appeared on our planet; seaweeds and salt-water animals are found in much older rocks than any that contain the fossils of land life. Moreover, though called a “wide waste of waters,” and seeming a complete desert as we gaze upon its restless surface on a dull morning, there is a greater number of animals and plants by count, and quite as large a variety, under the waves as above them, and the bottom of the sea—at all events near its margin—is more populous than any bit of woods you ever saw.

There exists in our ponds and ditches a race of plants so minute that it requires a powerful microscope to examine them. Under this instrument it is seen that they have delicate, flinty shells or armor, which is of a great variety of forms,—coiled, globular, boat-shaped, spindle-like, and so on,—and always beautifully sculptured. These minute and beautiful diatoms, as they are called, move about freely, and were long supposed to be animals; now they are known to be the simplest of seaweeds, consisting of only one cell. Since life first began, these diatoms, and other microscopic plants much like them, have swarmed not only in the fresh waters, but in all the oceans of the globe, furnishing food for mollusks and all the lowly animals whose food is brought into their mouths by the currents. Innumerable, and as wide-spread as the salt water itself, every one of these myriads of minute plants has left a record; for its delicate, glass-like shell was indestructible, and when the bit of life was lost, it sank slowly down to the bottom. What effect toward perceptible sediment could come from a thing so small that it would scarcely be felt in your eye? One or two, or even a million, would go for little; but century after century, through ages too long for us to comprehend, a steady rain of these exquisitely engraved particles of flint showered down upon the still sea-floor, almost as thickly as you have seen motes in a sunbeam, until there was deposited a layer, many feet in thickness, of nothing but diatom-skeletons. Though this went on to a greater or less extent everywhere in the sea, such deposits are not now to be discovered everywhere, because disturbing causes swept the shells away, or broke up the floor after it had been laid down; but in various parts of the world to-day, you may find wide beds of rock made up wholly of such skeletons, soldered together into hard stone; while in some regions the mud of our sea-bottom appears to consist of almost nothing else. The mighty chalk cliffs of Great Britain and the French coast were built up in precisely this way at the bottom of an ancient sea, whence they have been lifted, but they are composed of much besides diatoms.

From the simplicity of diatoms the vegetation of the sea can be traced upward through larger and more complicated kinds of plants until we reach the enormous algæ that break the gloom of black headlands by their brilliant tints, and furnish a lurking-place under their wide-spreading and dense foliage for hosts of marine animals—some hiding for safety, others to watch for prey.

Seaweeds grow in all latitudes, even close to the pole, but mainly along the shore, for below the depth of about one hundred fathoms none but microscopic forms are known. These latter float about, of course, and many of them have been thought to be animals because they seem able to move at their own will. They come to the surface as well as haunt the depths; and the Red Sea takes its name from the fact that a minute carmine-tinted alga occasionally rises to the surface in throngs so dense and wide as to tinge the water for miles at a stretch. The same thing occurs in the Pacific, where the sailors call it “sea-sawdust.”

The proper home of the seaweed, however, is a rocky shore between tide-marks or just below them, and it is because the eastern coast of the United States is deficient in rocks—at least south of Cape Cod—that this is poor in algæ, compared with other regions. The seaweed has no roots, and only clings to the rock for support; shifting sand therefore would not hold it, and there are great sandy deserts under the ocean, bare of algæ, as some land regions are sandy deserts naked of terrestrial plants.

It often happens, however, that masses of weed will be torn away from their moorings and set adrift. This does not necessarily kill them, for they go on flourishing while afloat, and such is supposed to be the origin of those great areas of “gulfweed” vegetation in mid-ocean called “sargasso seas.” You will remember that a branch of the Gulf Stream, striking over toward the Moorish coast of Africa, is turned southward there, and sweeps down to the equator, then westward again, circumscribing a broad region in the middle Atlantic whose only currents go round and round in a slow whirlpool; and here it is that the gulfweed concentrates in masses sometimes dense enough to impede the progress of a ship—Columbus reported among the wonders of his first voyage the trouble he had in sailing through it—and covering an area between the Azores and the Bahamas as large as the Mississippi valley. This is the Sargasso Sea ordinarily referred to in books, but it is not the only one. A thousand miles west of San Francisco there is a similar collection of floating plants, and others exist under like conditions in the southern oceans.

These floating meadows, as it were, are chosen as the abode of a long list of animals that rarely quit the safety and plenty of their precincts. Among these are innumerable pretty jelly-fishes, sea-worms, and mollusks without shells, which cling to the buoyant plants, and perhaps feed solely upon them. Here are to be had in abundance the fairy-like, rare pteropods, the richly purple janthinas towing their curious rafts of eggs, and no end of small crabs. Here a small fish, something like a perch, spends his whole time building a nest like a bird’s in the tangled weed-masses, and carefully guarding his treasures against the large marauding fishes that haunt the place to the dread of its peaceful inhabitants; and here those far-flying birds, the wandering albatross and the petrels, hover about in search of something to capture and eat. The Sargasso Sea is an extremely interesting part of the ocean, except to the luckless sailor becalmed and balked in its midst, as was Sir John Hawkins when he penned the following quaint observations, some three centuries ago:

Were it not for the Moving of the Sea, by the Force of Winds, Tides and Currents, it would corrupt all the World. The Experience of which I Saw _Anno_ 1590, lying with a Fleet about the Islands of Azores, almost Six Months, the greatest Part of the time we were becalmed, with which all the Sea became so replenished with several sorts of Gellies and Forms of Serpents, Adders and Snakes, as seem’d Wonderful; some green, some black, some yellow, some white, some of divers Colours, many of them had Life, and some there were a Yard & a half, & some two Yards long; which had I not seen, I could hardly have believed.

In favorable places a surprising variety of seaweeds can be picked out, and books exist by which you may learn the method of classification and names of the different species, the chief of which, for America, is Harvey’s splendid work, published by the Smithsonian Institution. Not only in the shape and colors of the _fronds_ (as the leaf-like expansions or branching tufts of the stem are called) do seaweeds differ greatly among themselves, but in size, varying from many diminutive or even microscopic sorts to the cable-like growths of California, which would measure a quarter of a mile in length if stretched out.

Algæ, as I have said, constitute, with very few exceptions, the whole vegetation of the salt water, together with a large part of the vegetation in fresh water; and they serve the same useful purpose there that land-plants do for the dry parts of the globe, continually making and throwing off the oxygen which is necessary to keep the water as well as the air pure. To this end they do a very important work.

This is not the whole of their service in ocean matters, however. I think it may be said that if it were not for seaweeds animals could not live in the ocean, as truthfully as that if it were not for herbage no animals would be able to exist on land. Seaweeds are fed upon directly by all sorts of salt-water life, from mollusks as big as your thumb to turtles the size of a dining-table, and they make a shelter for thousands of little fellows who never leave their shadow.

But this is a small part of the story. The diatoms, and other minute plants like them, form the main portion, if not all, of the food of a large number of sponges, polyps, mollusks, and other stationary, sluggish creatures, that otherwise, so far as I see, would not be able to live at all. These, in turn, are fed upon by larger predaceous animals. Thus, though the fishes and cetaceans may never bite a seaweed themselves (those large marine herbivores, the manatee and dugongs, subsist almost wholly upon it, however), they depend for food upon creatures that do. We may say, therefore, that the algæ form the basis of all ocean life.

Men have been able to make marine plants of service to them also—a resource more important formerly than now. In the last century, for example, the kelp trade was the one great industry of the islands at the west of Ireland and Scotland, employing thousands of persons, and paying vast revenues to the lordly owners of the shores. Kelp is the name of any large, leathery sort of seaweed, whose leaves float at or near the surface, supported by bladder-like expansions; but in this case the word meant the ashes of any seaweed dried in the sun and then slowly burned in kilns, clouding the air with huge volumes of strongly odorous smoke. The slow burning of the seaweed left the ashes fused into a solid mass, which was broken up like stone before being sold. In France this substance was called _varec_; and in Spain, where the algæ were mixed with beach-plants, cultivated for the purpose, and burned in shallow pits in the ground, it went to market as _barilla_.

In those days, kelp ash was the only source of the valuable alkali soda needed in manufacturing glass and soap. Then a French chemist discovered how to make such soda out of common salt, and the kelp ovens were abandoned, except a few in Scotland, supplying the demand for iodine and several other chemicals contained in this residuum which is so rich in iodine, used in photography and in medicine, that a ton of kelp ash will sometimes yield twenty pounds; yet only about 100,000 pounds are now produced in this way, while five times as much is obtained by chemical treatment of Chile saltpeter. It is a curious fact that barbarous people have long chewed seaweeds as a remedy in diseases for which physicians now prescribe iodine. Iodine is a violet dye, and the bluish and purple tints of many algæ, shells, and sea-animals appear to be due to the large amount of this element in sea-water.

Seaweeds and other marine plants, like eel-grass, are collected in great quantities by farmers in all parts of the world to be used as a fertilizer. Shell-mud, dead fish, and other marine products are also of high value as manure, on account of the large proportion of lime, carbon, and soda which they contain. Indeed, there is a kind of seaweed growing at great depths called the nullipore, which takes up so much lime from the water that its substance becomes almost like stone, so that the plant retains its shape and full size when dried. Some of these nullipores are beautifully fan-shaped, scarlet or pink, and are often seen in museums, marked _corallines_.

To return to the gathering of seaweeds by farmers, nowhere is it more customary than in some parts of New England. Thus the well-known Second Beach, just east of Newport, is in the fall of the year the scene of a vast activity in this direction. “It may easily happen,” we are told, “that the pilgrim to Whitehall, topping the hill on a brilliant autumn morning, shall come upon a scene in which quiet plays no part. The seaweed, that harvest which, ripening without labor, is neither bought nor sold, is setting inshore under the urgings of wind and tide, and scores of farmers have crowded to the spot to gather it. An artist could hardly wish a better subject for his pencil than one of these wild harvestings—the plunging horses, forced far out into the surf, their slow return, half swimming, half wading, dragging the heavily loaded rakes which leave behind them a long furrow of foam, the heaped-up kelp glistening in the sunshine, the oxen, yoked by fours, waiting for their load, the shouts of the men, the dash, the excitement, and beyond and above all, the wonderful blues and iridescent greens which are the peculiar property of Newport waters and the Newport sky.”

Cattle and horses that are accustomed to rough pastures, like the Scotch and Irish moors, eat seaweed and thrive on it, especially as winter fodder, and from several species are derived dishes for our own tables. The Irish moss, or carrageen,—which is not a moss at all, but a seaweed,—is the most important of these, and grows on both sides of the northern Atlantic. In England the market supply comes chiefly from the western coast of Ireland, while Massachusetts Bay gives America all that is wanted, principally the red, coral-like _Chondrus crispus_. The little port of Scituate, Massachusetts, is the chief point of supply, where many thousands of pounds are gathered. In early June, two or three hundred men and women go to the rocks at low tide and pick off the small brown plants, each man getting about a barrel in one day’s work. When the tide rises, the people get into small boats and pull up the moss with rakes.

The moss gathered each day is taken to the beach, where a gravelly space has been prepared, and is spread out to lie bleaching during all of the next day, when it is taken up, washed in tubs, and again spread out. The washing and drying in the sun continue for seven days, by which time it has bleached to a yellowish white. In cookery, jellies, _blanc mange_, and various methods of boiling in milk and mixing in soups are used to make it palatable. Besides being of value for food, carrageen serves to make sizing used by paper-makers, cloth-printers, hatters, and so on, to clarify beer in the brewery vats, as a medicine, and to make bandoline for stiffening the hair.

Other species beside the Irish moss serve as food in Europe, generally in a raw state, often proving the only salty relish which the Irish peasant has to eat with his potatoes. One of these is the _dulse_ of the Scotch (the _dillisk_ of Ireland), which also abounds in the Mediterranean, and is there made into a soup. The natives of the South Sea Islands eat algæ, which are extraordinarily abundant and varied in Oriental latitudes; and the poor among the Japanese and in the interior of China, where the weed is sent dried, prize it especially, because it has a sea flavor and saves salt, which with them is a costly luxury. These people mix it with vegetables and other materials, to form thick, delicious soups and dressings. A peculiarly bad-smelling sauce, prepared from seaweed, is among the exports China sends to Europe as a condiment.

Along the shores from Japan to Sumatra grows an alga which the natives of those coasts dry and keep as long as they please. When the substance is wanted they steep some of the dried pieces in hot water, where the weed dissolves, and then, having been taken off the fire, stiffens into a glue which is said to be the strongest cement in the world.

A kind of false isinglass, also, is a product of the Eastern seaweeds, and it not only enters into the pastry and confectionery of Chinese bakers, but serves to varnish and glue thin paper and to stiffen the light transparent gauzes of fine silk used in making Oriental screens, fans, hangings, etc., so that painters can decorate them. With a poorer quality the bamboo stretchers of paper umbrellas, lanterns, and various toys are smeared to give them hard and polished surfaces.

Seaweed has also been used in the manufacture of paper, and its complete success in this branch of industry is as yet hindered only by the difficulty of perfect bleaching. Certain species of it are utilized in enormous quantities by upholsterers as stuffing for sofas, chairs, and mattresses; in Japan it is formed into a substitute for window-glass; ornaments and small articles of use, like knife-handles, are made by several nations out of large dried seaweeds; and, finally, albums of preserved fronds are one of the prettiest things to be found in a naturalist’s cabinet.

The great majority of seaweeds grow between tide-marks, and they undoubtedly perform an important service in preventing the wear and tear of the coast in many situations. Some, however, grow in much deeper waters, and these, also, may serve as breakwaters of no mean strength. Such is the case, for instance, at San Pedro, near Los Angeles, California, where the abundant growth offshore forms such a barrier to the ocean rollers as to turn the open roadstead into a calm harbor within it.

This belongs to the group of gigantic kelps of which those at the Falkland Islands and about Tierra del Fuego are other and noted species. Were it not for the growth of this strong, cable-like, buoyant plant, large numbers of other plants and sea-animals would find it impossible to exist exposed to the violence of the South Pacific waves. Sometimes the stems reach twelve hundred feet in length, and the bladders by which the immense fronds are buoyed up are as big as kegs.

This gigantic seaweed is plentiful all along the Pacific coast of America to Alaska, and the natives of our northwest coast used to make extensive use of it in the way of ropes, etc. It was from this weed that, by a careful preparation, they made the lines for their harpoons and deep-sea fishing; and the bladders furnished them ready-made receptacles for eulachon oil, for water for their seatrips, and for other liquids.

A California correspondent of the New York “Evening Post” gave a pretty picture, not long ago, of one of the kelp patches at St. Nicholas Island, where the beds of this wonderful plant reach out for a mile or more, growing up from the rocks below and forming an effectual break; the seas losing their force in their effort to pass through the submarine meshwork.

The vines constitute a veritable forest, and, drifting over it in fifty or sixty feet of water, you may see a perfect maze of stems with broad leaves waving gracefully in the current, forming arbors, arches, and colonnades. Here, poised idly, in rich contrast to the olive-hued mass, may be seen fish of a bright golden color, others in tints of blue and green. The sea swell coming in causes an undulatory movement, and the long colonnades seem to melt one into another, reappearing in different shapes. When the leaves reach the surface, the shore wind, sweeping down from the hills, lifts them from the water, and they flutter in the air like mimic sails. Each leaf is a study. Many are encrusted with a delicate bryozoön, which presents the effect of white lace upon the surface, while a close inspection will reveal minute anemones, coiled tubular worms, which throw out flower-like organs of exquisite beauty; while flat shells lie among them, and crawling here and there are marvels of animal life, shell-less mollusks, which so mimic the weed that it is almost impossible to distinguish them.

This protective feature is a characteristic of life among the kelp forests that line the entire Pacific shores of North and South America, many animals simulating it so perfectly in color that the best-trained eyes often fail to observe them. This is especially true of the crabs and shell-less mollusks. The latter have not only assumed the exact tint of the weed, but are often covered with barbels of flesh that simulate the tangles of the substance. Upon the backs of the crabs are singular markings in green and white, which so resemble the minute incrustations of the kelp that the resultant protection is complete. [Compare illustration on page 252.] Each vine is fastened to a stone, and the clinging roots shelter hordes of creatures of various kinds—deep-water crabs, octopods, starfishes, and a host of others.