Marine plant

“ Marine vegetation.—The marine vegetation is divisible into different systems, like those prevailing on the land; but they are much fewer, as we might have expected, the temperature of the ocean being more uniform than that of the atmosphere, and consequently the dispersion of species from one zone to another being less frequently checked by the intervention of uncongenial climates. The proportion also of land to sea throughout the globe being small, the migration of marine plants is not so often stopped by barriers of land, as is that of the terrestrial species by the ocean. ”

“ In these deep pools grew also those bunches of broad dark-red leaves, which are probably the most conspicuous of all the marine plants in the collection. My readers will recognise them, when I say that they are generally about as large as one's hand, smooth and glossy, of a dark crimson hue, but apt to run off into a pale greenish tint towards the tips; their edges have often little leaves growing on them. ”

“ A light network of marine plants, of that inexhaustible family of seaweeds of which more than two thousand kinds are known, grew on the surface of the water. I saw long ribbons of fucus floating, of most delicate foliage, and some rhodomeniæ palmatæ resembling the fan of a cactus. I noticed that the green plants kept nearer the top of the sea, while the red were at a greater depth, leaving to the black or brown hydrophytes the care of forming gardens and parterres in the remote beds of the ocean. ”

“ Half an hour after the Canadian's last exploit we had regained the inner shore. Here the flora was represented by large carpets of marine crystal, a little umbelliferous plant very good to pickle, which also bears the name of pierce-stone and sea-fennel. Conseil gathered some bundles of it. As to the fauna, it might be counted by thousands of crustacea of all sorts, lobsters, crabs, spider-crabs, chameleon shrimps, and a large number of shells, rockfish, and limpets. ”

“ Order your agents to bring from the ocean living scalaria, and nautili, which are to be secured with least trouble during the mating season. We will prepare for them here a large basin of sea-water, with sand from the bottom of the ocean. In this we will plant sea-weeds, place our living shells among them, and feed them with star-fish, holothures, and other soft-bodied marine creatures. After a season our shell-fish will spawn; the eggs of the scalaria cling together—like a string of pearls; those of the nautili adhere to one another by sixes, in shape of a star. ”

“ As the localization of marine plants and animals is in a considerable degree determined by the nature of the rocks and their detritus, it follows that each part of this coast will have its more or less distinct Flora and Fauna. What now must result from the action of the waves in the course of a geologic epoch? As the sea makes slow inroads on the land, the place at which each group of strata crops out on the beach will gradually move towards the west: its distinctive fish, mollusks, crustaceans, and sea-weeds, migrating with it. ”

“ The distribution of marine plants seems mainly deter mined by light, temperature, and depth, a further influence being exerted by the character of the shores. The diminu tion of liyht iu its passage through sea-water is so rapid, that the quantity which penetrates to a depth of 250 or 300 fathoms may be regarded as almost infinitesimal ; and in conformity with this we find a very rapid diminution of Algal life below the depth of 100 fathoms. ”

“ Now we come to the real use of sea plants. They are food for all the hosts of small animals of the sea. These eat it as it grows; or else, like the mussel and oyster, swallow the tiny scraps of it which float everywhere like so much dust.
The shell-fish, and other animals which feed on sea plants, are themselves eaten by other sea creatures, and these in their turn are eaten by crabs, lobsters and fish, which are eaten by us. It reminds you of a chain. The first link in the chain is the sea plant, the last links are the fish and ourselves. ”

“ Still other variations, as of strength of currents, salinity, etc., exert an influence in this realm and lead to great diversity in its living organisms. Throughout its entire extent, however, the continental shelf abounds in both plant and animal life.
The plant life of the sea, as has been shown in recent years by the use of the dredge and net, is most abundant at the surface and is practically absent at the bottom where the water is over 100 fathoms deep. The animals of the sea, like those of the land, are dependent primarily on plants for their food. ”

“ For who, after all, to take a few broad instances (not to enlarge on the great root-wonder of a number of distinct individuals connected by a common life, and forming a seeming plant invariable in each species) , would have dreamed of the “bizarreries” which these very zoophytes present in their classification?
You go down to any shore after a gale of wind, and pick up a few delicate little sea-ferns. You have two in your hand, which probably look to you, even under a good pocket magnifier, identical or nearly so. ”

“ The plants render the water fit for the maintenance of animal life, while the animals check the too rapid increase of vegetation. Thus, the success of our aquarium will depend upon the proper balance of animal and vegetable life. We select the green and red weeds, as the brown and olive are apt to discolour the water. Sea-plants have no roots, but adhere by minute discs to the surface of the rock; a piece of stone has accordingly to be knocked off with each plant, in order that it may be removed to our glass tank. ”

“ 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. ”

“ Under such extreme conditions none of the higher land plants venture down towards the unfriendly sea. To see the overlap of the terrestrial and maritime vegetation well developed we seek conditions entirely different, where amid shallow inlets and salt-marshes land and sea merge imperceptibly.{203} Here the absence of higher plants from the areas below high water, as compared with their abundance above water-level, is a conspicuous feature. ”

“ As this era begins, the sea bottoms, the extensive continental shelves, and the numerous shallow near-shore basins are covered with prolific vegetation. The more simple and primitive forms of animal life have already developed from preceding vegetable organisms, and the early animal organisms have gradually made their way along the extensive coast lines of the various land masses until the many inland seas are teeming with primitive marine life. ”

“ The bed of the ocean, from the tiny lakelets left by the retiring tide to the greatest depths ever reached by trawl and dredge, is found to be teeming with exquisite forms of life. Delicate plant-like forms are found clinging to rocks and shells, or spreading themselves over the broad fronds of the algae. Every peculiarity of vegetation is mimicked; graceful stems rising from tangled roots send out branches which bear raceme-like clusters of buds, and delicate bells whose beauty no words can describe.
Fig. 5.—Roving Medusa of Tubularia indivisa. ”

“ In the inky darkness of the ocean depths, amid absolute stillness and a temperature little above freezing, plant life of any sort is unknown. Only the flinty skeletons of diatoms and other minute forms of vegetable life which inhabit the surface layers, raining slowly down throughout the ages, tell that plant life exists in the sea at all. ”

“ By following up the clue supplied by the floating seed, we have arrived at the conclusion with respect to the British flora that plants with buoyant seeds or fruits gather at the water-side. But we have yet to inquire why some of these plants are “located” at the sea-coast and others on the borders of ponds and rivers. Mere buoyancy aided by chance has not determined the choice. There are definite principles at work in the economy of plant-life that make the selection for each plant. ”

“ And by and by we reach the sea, and there we find masses of tangled seaweed, the plants of the salt water, while all along the shores myriads of living creatures are left by the receding tide. In the rocky pools we find active life busily at work. Thousands of tiny acorn shells, scarcely larger than the head of a good-sized pin, cover the rocks and fling out their thread-like arms in search of food. ”

“ The great majority of water plants send their flowers up above the surface to be pollinated by wind or (more rarely) by insects. It may be noted that few of the more highly evolved groups of Seed{201} Plants are represented in the aquatic flora; wind-pollinated flowers of a rather primitive type of structure are the rule in our lakes and rivers; which points to an early assumption of the aquatic habit, and suggests that the land is more favourable than the water for the evolution of higher types. ”

“ Organic Remains.—The forms of life buried in the carboniferous system of strata are exceedingly numerous and varied, and, being generally in an excellent state of preservation, allow of a most strict comparison with existing types. They consist of very many races of plants, abundance of zoophyta, multitudes of mollusca, some Crustacea, many fishes, but, as far as we yet know, neither reptiles, birds, nor mammalia. Many of the plants, indeed by far the greater number, are of terrestrial growth: all the zoophyta, and nearly all the mollusca, Crustacea, and fishes, are marine. ”

“ THE VEGETATION OF THE MARINE AQUARIUM. As the forest must be planted before its denizens can luxuriate in its shades, so the submarine shrubbery of the Aquarium must be perfected before the aquatic animals can be introduced. For it has been shown, in tracing the history of the experiments which resulted in the establishment of the principles that regulate the formation of Aquaria, that it is by plants only that a supply of oxygen can be kept up, sufficient for the health and existence of all forms of animal life beneath the water. ”

“ Seaweeds and their like, which propagate by a kind of spores, may remain below the surface for ever; but flowering plants for the most part must come up to the open air to blossom. The sea-weeds are in the same position as fish, originally developed in the water and wholly adapted to it, whereas flowering plants are rather analogous to seals and whales, air-breathing creatures, whose ancestors lived on land, and who can themselves manage an aquatic existence only by frequent visits to the surface. ”

“ The number of plants with seeds or fruits between fresh water and sea-water in specific weight is very small, probably not over 2 per cent. of the total. Most seeds or fruits that sink in fresh water sink also in sea-water, and most that float in sea-water float also in fresh water. Nature has thus created a wide gap between the sinking and the floating seed; and nearly all of the work of the present currents in plant-dispersal might have been effected, so far as the density is concerned, in fresh water. ”

“ Very frequently, however, they will be so beaten about and defaced, that they will be comparatively valueless; if enveloped in tangled masses of sea-weed, they are likely to be preserved from injury; and such heaps of uprooted marine vegetation will often afford a rich harvest to the young conchologist, who should always carefully examine them. ”

“ They grow on the rocks, in pretty coloured tufts.
If you dive still farther, into the dark depths of the sea, you find beds of ooze and slime, and rocks and weird fishes, but no plants. Why is this? Like the land-plants, these sea-plants must have light. They cannot grow in the blackness of very deep water. Can you guess why some sea-weeds are green and others red? Those growing in the shallow water of the shore are green, like land-plants, because the sunlight reaches them. Only part of the light can pass through deep water; and so, in these shady places, the sea-weed is reddish in colour. ”

“ Just so ocean-flowers, and sea-tints can only live in their own element, which is not air, but water. And the faces on our water-pansies—for we have them—would soon fade in what to them would be lifeless air, just as the garden pansies would lose their bright faces in the salt sea.
Great quantities of seaweeds float ashore and are often dried and used as fuel, or perhaps are put around garden plants to make them grow.
But nothing that grows on the land, or in the water, can exchange places one with the other and keep alive. ”

“ Seaweeds, and in fact all the algæ, have green coloring matter in them, even where this is masked by reds and browns, as is the case in some particularly showy kinds. As you will find in the section on “Leaves as Factories for the Making of Food,” no plant with green coloring matter can live in the dark. That is why seaweeds are not found in the great deeps of the sea, some of which are several miles below the shore line along the coasts, and are so cold and dark that neither plants nor animals can grow in them. ”

“ Freshwater plants and animals.—The remains of species belonging to those genera of the animal and vegetable kingdoms which are more or less exclusively confined to fresh water are for the most part preserved in the beds of lakes or estuaries, but they are oftentimes swept down by rivers into the sea, and there intermingled with the exuviæ of marine races. ”

“ The finest collections of shells, however, are to be made at the sea-side, for the marine mollusca are both more varied in kind and more abundant than the land and fresh-water ones, and quite an extensive collection may be made in the course of an afternoon's ramble along the shore; it is necessary, however, to carefully reject such specimens as are worn by having been rolled by the waves upon the beach, as they are not of any great value in a collection; it is better, in fact, if possible, to go down to the rocks at low water and collect the living specimens. ”