“At ebb tide, after a storm, sandy beaches are often thickly strewn with great masses of seaweed, some of which have been torn from nearby coasts, while others may have drifted on the waves for hundreds or even thousands of miles. On rocky coasts, similar masses of drift are left by the receding tides; but here one may also see a great variety of marine plants hanging from the rocks between tide marks, or with their tops floating upon the surface of the water, while the lower portions are deeply submerged. The briefest sojourn by the seashore may suffice to give one a little glimpse into the neglected science of algology — the study of seaweeds. The word looks erudite and forbidding; but it need not be prosecuted very deeply in order to make it productive of both pleasure and profit. Certainly no division of nature study is more generally neglected; while few are more fascinating to the initiated. Everywhere in the ocean there is plant life. In some parts of the world there are dense submarine forests composed of seaweeds that exceed in length the height of the tallest forest trees with foliage covering the surface of the ocean so thickly that the passage of ships is impeded. The Sargasso Sea is an undulating marine prairie as large as the whole continent of Europe, with vast masses of seaweeds drifting ceaselessly in the water. Wherever there is sea water, there are millions of seaweeds so small that they are invisible to the unaided vision.
If one were to ask every person he met in a day spent along the coast what were the uses of algae, or seaweeds, it is probable that the majority would reply that they were of no use at all. Some would frankly say that they did not know; and a few might answer that they were used to a limited extent as fertilizers, and in the preparation of drugs and chemicals. Yet, though nature is often prodigal, it is never purposeless. Algae are the only form of vegetation that exists in sea, lake and ocean, covering two-thirds of the superficial area of the globe. It is evident that they must play a highly important part in the economy of nature.
What that part is is not at all mysterious. The seaweeds serve the same purpose in the oceans that the infinite variety of plant life on land serves there — that of making animal life possible. They take the elements existing in water as ‘impurities,’ and by the inscrutable alchemy of nature transmute them into materials essential to animal life. Plants feed upon mineral substances, transforming these into organic matter, such as starch, sugar and albumen, which form their own structure, making them into food essential to animals. But for the seaweeds, therefore, there could be no animal life in the ocean. These form the sole subsistence of multitudes of fishes, mollusks and other forms of marine animals; and those that do not live entirely or at all upon the plant life of the seas must prey upon smaller or weaker creatures that do.
This is the chief office of algae, although they have many minor uses. Bordering many rocky coasts are vast marine growths that answer the purpose of breakwaters, smoothing and placating the waves and thus preventing the rapid wearing away of the coast line. Another use to which man has put seaweeds is that of fertilizing the soil of farms and orchards near the seashore, particularly along the coast of New England, the British Isles and Western Europe. In Holland they have been extensively employed in the building of dykes. Until in comparatively recent years, seaweed ash supplied most of the potash used in the manufacture of glass and in the preparation of iodine. Many varieties are largely composed of gelatin and some of these are an article of diet among the Chinese, Japanese and Sandwich Islanders. Another gelatinous species is employed by a swallow-like bird of the East Indies for nest building. These nests are found in great numbers in caves along the shores of Java and neighboring islands, and are gathered and shipped to China, where they command high prices, being used in the preparation of the famous birds’ nest soup. Several kinds, known by the general name of dulse, are used to a limited extent as human food in Scotland and Ireland; and both kelp and dulse are fed to swine and cattle. A variety known as Irish moss is used in the making of blanc mange and other delicacies; and other varieties are used in the manufacture of glue and varnishes, in the preparation of drugs, and for stuffing mattresses, cushions and upholstered furniture.
Leaving out of consideration the more exact methods of classification employed by algologists, algae may be divided into their four great botanical sub-classes on the basis of color, although this method of identification is not always correct. The blue-green or purple sea-weeds are all small — mostly microscopic — with two genera consisting of fine, hair-like, filamentous plants. The grass-green algae are among the most widely diffused of plant forms, being found everywhere between tide marks, floating on the surface of the deep sea, covering damp earth, walls, palings and tree trunks, sticking to the surface of leaves in damp forests and existing in every brook, river, ditch, pond or casual pool of rain water. Many are microscopic in size, but others are quite large, resembling grass, leaves, mushrooms and a multitude of other common land plants.
The olive green and brown seaweeds embrace many of the most remarkable algae, varying in size from a few inches in length to plants many times the length of the tallest forest trees. To this sub class belongs three-fourths of the vegetation that grows between tide marks on all rocky coasts, and probably five-sixths of the seaweeds that are washed ashore. The red seaweeds are the most highly organized of marine plants, their delicate texture and pink, red and purple coloring malting them very beautiful and attractive. Most of them grow only In deep water; but these are often cast ashore, while many species grow just below the water mark and in pools among the rocks.
Among the smallest, of all plants are the diatoms, not more than one one-thousandth of an inch in diameter, and visible only with the aid of a powerful microscope. They have a shell-like covering and float everywhere on the surface of the ocean in inconceivable numbers, forming the basis of the food supply of fishes. Their shells fall to the bottom of the sea, where in the course of ages they form deposits many feet in thickness. Upon a fossilized bed of diatoms the city of Richmond, Virginia, is built; and similar deposits are found in Nevada and California.
Everyone has read of the wonderful phosphorescent effects seen at night in tropical seas; but not everyone may know that these effects are due to the presence of myriads of microscopic algae — the pyrocistis noctilucca. To the periodical appearance of billions of little algae, the Trichodesmium, the Red Sea owes the characteristic that gives it its name; and a related plaint, the Protococcus nivalis, is responsible for the phenomenon of red snow, sometimes seen in the high latitudes of the arctic regions, and on the tops of snowy mountains, where no other form of vegetation can exist.
It is said that there are more than 15.000 species of algae. One of their distinctive characteristics is that they contain only one kind of cells, these being the soft cells that correspond to those composing the pulp in the leaves of flowering plants. There is, therefore, no distinction of bark, leaf or stem in seaweeds — the absence of woody cells making this impossible. Similarly, there are no roots — the root-like expansions and filaments that anchor the higher plants to the rocks being composed of the kind of cells that form the body of the plant (botanically known as the phallus, or frond, and answering no other purpose than that of hold-fast), whereas true roots convey nourishment from the earth to the stalk and foliage. The seaweeds absorb all their nourishment directly from the water.
Nevertheless, the higher forms of algae attain curious and beautiful shapes, resembling mosses, grasses, ferns, shrubs and forest trees. Many of them so closely simulate the forms of roots, stems, branches and leaves that it is difficult to keep in mind the fact that the botanical basis for such distinctions is entirely lacking. When this is remembered, it is permissible and convenient to refer to the parts of the larger seaweeds by the names, roots, stalks and leaves or foliage, on account of their resemblance to the parts of common plants.
A peculiarity of many of the higher seaweeds particularly of the brown and olive-green sub class, that never fails to attract attention, is the globular air sacs that give buoyancy to that plant, floating upon the surface of the waves and thus maintaining the plant in an upright position, or inclined in the direction of the current. But for this provision of nature, the plant would fall in a formless mass upon the rocks. Sometimes the leaf-like foliage grows out of the tops of these air vessels, and sometimes the air sacs are distributed among the foliage, but in either case the foliage is scanty or profuse in proportion to the sustaining power of the air vessels.
The extreme development of the air vessel is found in a great seaweed called the ‘sea otter’s cabbage,’ or, in the language of the botanists, Nereoystis Lutkeana, growing off the coast of Alaska and among the Aleutian Islands. The air vessel is a cylindrical bladder shaped like a barrel, six or seven feet in length, anchored by a slender, cord-like appendage (corresponding to the stalk of land plants) that often exceeds 300 feet in length, fastened to the rocks at the bottom of the ocean. From the buoyant vesicle grows a mass of foliage, consisting of 40 or 50 great, leaf like forms, each one of which may be 50 feet or more in length. Upon these air vessels the sea otter finds a convenient lair, whence to pursue his favorite vocation of fishing for a living — hence the name, ‘sea otter’s cabbage.’ The long cord that keeps the air sac from drifting with the waves to certain destruction on the coast is so strong and slender that the Indians of the Aleutian Islands make use of it for fishing lines.
At the other extremity of the American hemisphere is a related plant, which the algologist call the Macrocyntis, that far exceeds in length even this northern giant. One writer states that it is often 1,500 feet in length. Instead of one large air sac, the Macrocyntis has a large number of small ones, supporting a floating mass of vegetation hundreds of square yards in area.
The most striking seaweed of the California coast is identical with the ‘sea otter’s cabbage’ of the far north, excepting in the matter of size. At ebb tide, after a storm, hundreds of these curious plants may be found upon the beaches, mingled with tangle, kelp and many other varieties of algae, and never failing to attract the attention and excite the wonder of sojourners along the coast. The air vessels are usually as round as oranges, varying in size from an inch or less in diameter up to eight or ten inches, while the cord-like anchor line is often 20 or 30 feet long. Occasionally the air sac is connected with the ‘stalk’ by a thick, tubular prolongation several feet long. In some of the curiosities very attractive little baskets are for sale, made from these air sacs, dried and cured by a secret process; as well as canes formed by drying and twisting the long tubes; and dolls whose heads are made of small air vessels, with bodies and limbs made of seaweeds, and hats, boots and clothing fashioned from the same material.
Less conspicuous, but not less interesting, are numerous species of Sargassum. It is noted for the large number of small, currant-like air sacs that sustain the foliage. One species of this composes the vast aggregate of floating vegetation in the Sargasso Sea, in the North Atlantic. Specimens of Sargassum brought from the Sargasso Sea are so thickly covered with air sacs that they resemble bunches of grapes. Both the Atlantic and the Pacific coasts have many species of this interesting order.
Of the more common varieties of seaweed seen on every coast, the most interesting are the tangles, oarweeds, devil’s aprons, sole leather, kelp and sea furbelows, all belonging to the genus Laminaria —the most numerous and most widely distributed of the large seaweeds.
The chief attraction of a trip to Santa Catalina Island off the California coast, is a view of the so called ‘Marine Gardens,’ through the glass-bottomed boats. Here may be seen a great variety of kelps and a few of the deep water sea mosses, in their natural habitat and positions, with thousands of gorgeously colored fishes — red, deep blue, green, brown and mottled — ‘at home’ among them, while strange, sluggish creatures cling to the rocks. It is claimed that nine-tenths of all the tourists who visit Southern California take the trip to Santa Catalina, where the ‘Marine Gardens’ give to very many their first real glimpse of the submerged wonders of the deep.”