Marine biology

“ They rest upon those not less remarkable beds of limestone, of which our capital is built, in the more or less compact texture of which the patience and sagacity of our naturalists, and of several ardent collectors, have already detected more than 800 species of shells, all of them marine, but the greater part unknown in the presently-existing sea. They also contain only bones of fishes, and of cetacea and other marine mammifera. ”

“ A marine formation of great extent and thickness, consisting of strata of limestone and clay, which abound in extinct species and genera of marine shells, Corals, Insects, Fishes, and terrestrial and marine Reptiles. Land plants of many peculiar types, and the remains of two genera of Mammalia. ”

“ Prominent among vestigial structures, though less easy for beginners to understand, are those that point to piscine ancestors and which, therefore, smack of the sea. Embryology points indubitably to the fact that the ancient, geologic progenitors of man once lived a marine life. In the history of the globe there was a time when all [196] the animals lived in the sea. Land animals appeared as later creations. Man, in evolving from the primitive protozoan, passed through a marine-worm phase and finally, through the ages, attained to the fish stage. ”

“ It has been found possible to accustom marine fish to live in fresh water; but as such changes in fish, and other marine animals, have been chiefly observed in a state of nature, they do not properly belong to our present subject. ”

“ 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. ”

“ Thus we perceive that these creatures, though they are regarded as being so low in the scale of creation, may nevertheless be regarded as agents of much importance in the terrestrial economy; for we perceive that they are capable of spreading over certain parts of the ocean those benign mantles of warmth which temper the winds, and modify, more or less, all the marine climates of the earth. ”

“ The dews, the rains, and the rivers are continually dissolving certain minerals of the earth, and carrying them off to the sea. This is an accumulative process; and if it were not compensated, the sea would finally become, as the Dead Sea is, saturated with salt, and therefore unsuitable for the habitation of many fish of the sea. The sea-shells and marine insects afford the required compensation. They are the conservators of the ocean. ”

“ Ten species have been distinguished in different seas and oceans. They usually attach themselves to some hollow part of the bodies of marine animals, preferably entering the respiratory cavities of star-fish. ”

“ Care must be taken to observe whether, when the sun shines and the light is bright, the silvery bubbles of oxygen form upon the fronds of the marine vegetation; and if not, it is certain that the marine plants are not in a healthy state, and must be renewed. ”

“ Of the molluscous life of the age in this region we, know almost nothing, since the marine deposits which contain its remains are not now above the ocean-level, and the fresh-water and estuary beds exposed to our observation have yet yielded none. Of the land-animals scarcely any traces have been found except their footprints. ”

“ This was the great age of individual animal organismal evolution, though many of the basic changes, such as the transition from plant to animal, had previously occurred. The marine fauna developed to the point where every type of life below the vertebrate scale was represented in the fossils of those rocks which were laid down during these times. But all of these animals were marine organisms. No land animals had yet appeared except a few types of worms which burrowed along the seashores, nor had the land plants yet overspread the continents ”

“ As the animal lives in the open sea, and probably wants a place of rest, I suppose this beautiful and most anomalous structure is adapted to take hold of floating marine animals.
In deep water, far from the land, the number of living creatures is extremely small: south of the latitude 35°, I never succeeded in catching anything besides some beroe, and a few species of minute entomostracous crustacea. In shoaler water, at the distance of a few miles from the coast, very many kinds of crustacea and some other animals are numerous, but only during the night. ”

“ Let us take, in connection with all this, the fact that we are dealing with the deposits of the earliest ocean known to us—an ocean warm and abounding in the mineral matters suitable for the skeletons of humble animals, and fitted to nourish aquatic plants. The conditions were certainly favourable to an exuberant development of the lower forms of marine life; and in later times, when such conditions prevail, we generally find that life has been introduced to take advantage of them. ”

“ Let it be noted also that those tertiary species which have continued with little change down to our days are the marine animals of the lower grades, especially mollusca. Their low organization, moderate sensibility, and the simple conditions of an existence in a medium like the ocean, not subject to great variation and incapable of sudden change, may well account for their continuance ”

“ We find the marks of marine animals in the most solid parts of the earth, consequently those solid parts have been formed after the ocean was inhabited by those animals which are proper to that fluid medium. If, therefore, we knew the natural history of these solid parts, and could trace the operations of the globe by which they have been formed, we would have some means for computing the time through which those species of animals have continued to live. ”

“ When we look back by the help of geological science to the more remote past, through the epochs immediately preceding our own, we find evidence of marine animals—which lived, were reproduced, and died—possessed of organs proving that they were under the influence of the heat and light of the sun ”

“ Yet, while rivers may thus carry down the same fluviatile and terrestrial spoils into two or more seas inhabited by different marine species, it will much more frequently happen that the coexistence of terrestrial species of distinct zoological and botanical provinces will be proved by the identity of the marine beings which inhabited the intervening space. ”

“ Upon this supposition — the like of which nature warrants throughout her whole domain — we may conceive how the marine animals of which we have been speaking may impress other features upon the physical relations of the sea by assisting also to regulate climates, and to adjust the temperature of certain latitudes. ”

“ Among the many conditions which have produced great diversity in numbers and distribution of marine organisms during geologic time are temperature, depth of water, clearness of water, nature of sea bottom, degree of salinity, and food supply. River and lake deposits also not uncommonly contain remains of organisms which inhabited the waters, but also others which were carried in. “Surrounding trees drop their leaves, flowers, and fruit upon the mud flats, insects fall into the quiet waters, while quadrupeds are mired in mud or quicksand and soon buried out of sight. ”

“ The depth of these sands it is impossible to determine; but thousands of feet may not reach their soundings. And as to organic remains, they are most favorably situated and composed for attracting and sustaining every kind of marine creature: it is upon the banks that border the coast of North America that the most extensive fisheries are carried on, because these are the abodes of those myriads of invertebral animals—the molluscs, annelides, and zoophytes, types of the older formations—which serve for the food of fishes, the ctenoids and cycloids of maritime enterprise. ”

“ I maintain that marine stations are necessary for biological science, since nowhere but in the sea can there be found a host of types whose study is indispensable if one desires to form a clear and concise idea of the ensemble of the organic world, of which we ourselves are members. Now, the greater part of these organisms, vegetable as well as animal, are so delicate that, notwithstanding our improved methods of preservation, we can not acquire even an approximately correct idea of their characters unless they can be studied in their natural medium—the sea. ”

“ Among these the most numerous are the remains of marine animals, and in some instances shells and corals occur in such abundance as to form the principal part of extensive beds. Every part of the earth exhibits similar, or nearly similar formations; and not only are marine fossils met with in the interior of continents, and at great elevations above the sea, but a vast variety of plants, corals, shells, fish, reptiles, etc., are found, of species dissimilar to any at present on the land or in the waters. Besides rocks, we meet with earthy formations on the surface. ”

“ The shallow-water, or littoral, fauna includes all marine animals which belong neither to the deep-sea nor to the surface fauna, and is the most important of all three.The shallow-water fauna. In addition to the great bulk of marine invertebrates, the littoral fauna may be taken to include the reef-building corals (whose distributional limitations under the influence of temperature-control have been already mentioned) and likewise seals and sea-cows among mammals, and turtles among reptiles. ”

“ A most curious and interesting set of phenomena are those which often occur when a group of fishes, once marine, take by practice to inhabiting freshwater rivers; or, vice-versâ, when a freshwater kind, moved by an aspiration for more expansive surroundings, takes up its residence in the sea as a naturalised marine. ”

“ The most prominent and remarkable result of the voyage was the final establishment of the fact that the distribution of living beings has no depth-limit, but that animals of all the marine invertebrate classes, and probably others also, exist over the whole of the flora of the ocean. ”

“ 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. ”

“ About forty species, contained in four genera, compose this Family: they are all marine, and are found in both hemispheres, principally in the intertropical seas. A few inhabit the Mediterranean, and one is by no means uncommon around the British Isles, and on the northern shores of Europe. ”

“ What myriads has the microscope revealed to us of the rich luxuriance of animal life in the ocean, and conveyed to our astonished senses a consciousness of the universality of life! In the oceanic depths every stratum of water is animated, and swarms with countless hosts of small luminiferous animalcules, mammaria, crustacea, peridinea, and circling nereides, which, when attracted to the surface by peculiar meteorological conditions, convert every wave into a foaming band of flashing light. ”

“ Of Marine Fishes, some roam the wide ocean, some play around the coral islands of the tropics, others affect the mud, or the sands of the shallows; some linger near the estuaries of great rivers; others come in mighty armies around the coast at particular seasons, retiring again to the deep water in the offing; finally, some habitually keep near the surface, while others rarely rise from the vicinity of the bottom. ”

“ The fauna is made up of a modified marine and a modified fresh-water fauna, and always has its nearest relatives in the open sea, on the one hand, and in the rivers and connecting fresh-water lakes, on the other. Since the species contributed by the marine waters are so much more numerous than those contributed by the rivers, the greater number of the species in the brackish water will be related to marine forms. ”

“ Turning to the sea, we find the same law. No two marine faunas are more distinct, with hardly a fish, shell, or crab in common, than those of the eastern and western shores of South and Central America ”

“ The appearance of what are called fresh water shells, in alternate beds with marine animals, being sometimes observed in newer flœtz rocks in great abundance, seems to indicate a reiterated retreat and return of the sea. But however meritorious the labours of naturalists, through whom attention has been directed to the subject, may be in other respects, we are nevertheless disposed to entertain doubts concerning their conclusions. In our own seas and ponds upon the coasts, we observe the same [425] testaceous animals growing equally well in salt water, and in water nearly fresh ”

“ Most marine animals have a wide range; and we have seen that with plants it is those which have the widest range, that oftenest present varieties; so that with shells and other marine animals, it is probably those which have had the widest range, far exceeding the limits of the known geological formations of Europe, which have oftenest given rise, first to local varieties and ultimately to new species; and this again would greatly lessen the chance of our being able to trace the stages of transition in any one geological formation. ”