The fresh & salt-water aquarium
Wood, J. G. (John George), 1827-1889
0^ T, uT ^ >H| ^ ty vwtl U Kt ^ ^ Vv' t- v ^\ ft,^-i> ? ~ ^ A^si ivv't. V(-V(-€^ H TW W&i/<L$ "-nr Wv^V-tj v ^llAw^ ^ (“oAceV Y^^eVe l V\^ ( THE ERESH AND SALT-WATER WYMAN AND SONS, PRINTERS, BEAT QUEEN STREET LINCOLN’S INN FIELDS, LONDON, W.C. THE WAVES— THEIR INMATES. Plate XII. THE FRESH & SALT-WATER AQUARIUM BY THE Rev. J. G. WOOD, M.A., F.L.S., etc. AUTHOR OF “COMMON OBJECTS OF THE COUNTRY AND SEASHORE” “THE ILLUSTRATED NATURAL history” WITH ILLUSTRATIONS LONDON: GEORGE ROUT LEDGE AND SONS BROADWAY, LUDGATE HILL NEW YORK: 9 LAFAYETTE PLACE BY THE SAME AUTHOR. Anecdotes op Animals. With Illustrations by Harrison Weib. 3s. 6d. My Feathebed Feiends. With Illustrations by Habbison Weib. 3e. 6d. The Boy’s Own Natural History. With numerous Wood- cuts by William Habyey. 3s. 6d. White’s Natural History op Selbobne. Edited by the Rev. J. G. Wood. With numerous Hlustrations. 3s. 6d. a he Common Objects op the Sea-shobb. With Coloured Illustrations. 3s. 6d. Common Objects op the Country. With Coloured Illustrations. 3s. 6d. The Common Objecis of the Microscope. With Coloured Illustrations. 3s. 6d. CONTENTS. Introduction . Page 1 CHAPTER I. Algas or Seaweeds . 16 CHAPTER II. Fishes . 25 CHAPTER III. Fishes ( continued ) . 37 CHAPTER IV. Molluscs . 44 CHAPTER V. Molluscs and Crustacea . 53 CHAPTER VI. Annelids 72 Vi CONTENTS. CHAPTER VII. The Star-fish . Page 87 CHAPTER VIII. Sea Anemones . 101 CHAPTER IX. Fishes . 114 CHAPTER X. Fishes ( continued ) . 126 CHAPTER XI. Fresh-water Molluscs, Crustacea, and Spiders 140 CHAPTER XII. Insects . 155 CHAPTER Xin. Insects ( continued ) . 166 DESCRIPTION OF PLATES, JPlate II. having been spoiled in the printing is omitted. The reader will notice that no reference is made to it in the text. PLATE I. FIG. PAGE. 1. Purple Laver ( Forphyra laciniata . 18 2. Carrageen ( Chondrus crispus) . 19 3. Cladophora pellucida . 22 4. Ulva latissima (green laver) . 16 5. Codium tomentosum. 6. Bryopsis plumosa . 24 7. Enteromorpha. PLATE III. 1. Patella pellucida . 64 2. Common Periwinkle . 63 3. Trochus cinerarius . 62 4. The Squid . 44 5. Doris coccinea . 48 6. Wentletrapshell . 51 7. The Mail-shell ( Chiton marc/inatus) . 54 8. Goniodoris nodosa . 48 9. Scyllsea pelagica . 47 10. Gemellaria loricata . 65 11. Scrupocellaria scruposa 55 12. Bugula avicularia . 65 13. Eolis papillosa . 47 14. The Sea-mat ( Flustra foliacea) . 54 15. Bicellaria ciliata . 55 16. Do. magnified 55 17. Doto fragilis . 46 PLATE IY. 1. Green Crab ( Carcinus mcenas) . 55 2. Harper Crab, or Sea Toad (Ilyas araneus) . 59 3. Corophium longicorne ... 69 4. Caprella linearis . 69 5. Slender - legged Crab (Stenorhynchus pha - langium ) . 60 fig. pagb 6. Phoxichilidium cocci- neum . 70 7. White Shrimp ( Paleemon squilla) . 67 8. Soldier Crab ( Pagurus Bernhardus) . 63 9. Common Shrimp (Craw- gon vulgaris) . 67 PLATE Y. 1. Sea Urchin . 83 2. Brittle Star . 91 3. Sun Star (Solaster pap - posa) . 91 4. Cydippe . 105 5. Sarsia . 107 6. Saballa alveolaria . 75 7. Sea Mouse (Aphrodite aculeata) . 72 8. Sand Mason, or Shell- binder . 80 9. Serpula contortupli- cata . 73 PLATE VI. 1. Actinia mesembryanthe- mum . 92 2. Plumose Anemone ( Ac - tinoloba dianthus) . 101 3. Cave-dwelling Anemone (Sagartia troglodytes) 102 4. Cave-dwelling Anemone, closed and unattached 102 5. Coryne . 103 6. Tubularia indivisa . 103 7. Tubularia gracilis . 103 8. Sertularia argentea . 104 9. Plumularia falcata . 104 10. Laomedea geniculata . 104 11. Laomedea gelatinosa . 104 12, Campanularia volubilis... 104 DESCRIPTION OF PLATES. vm FIG. PAGE. PLATE VII. 1. Common Newt (male) ... Ill 2. Do. (female) ... Ill 3. Common Water Spider (Argi/ronetra aquatica) 152 4. Frog-bit . 110 5. Anacharis . 110 6. Yallisneria . 110 Fresh- water Shrimps... 150 PLATE VIII. 1. Trout . . . 131 2. Perch ( Perea Jluvia'ilis) 120 3. Carp . 130 4. Pike, or Jack ( Esox Lucius) . 129 5. Ten-spined Stickleback... 115 6. Three-spined Stickleback 114 7. Eel . 131 8. Miller’s Thumb ( Cottus gobio ) . 117 PLATE IX. 1. Planorbis vortex . 143 2. Paludina vivipara . 142 3. Ancylus fluviatilis . 144 4. Larva of Colymbetes . 158 5. Bithynia tentaculata . 140 6. Limnaeus stagnalis . 143 7. Larva of Acilius sulcatus 158 8. Larva of Hydrophilus piceus . 161 9. Fresh-water Sponge . 145 10. Cristatella mucedo . 148 11. Larva of Whirlwig . 160 12. Larva of Great Water- Beetle . 156 PLATE X. 1. Dyticus marginalia . 156 2. Hydrophilus piceus . 161 3. Colymbetes . 158 4. Acilius sulcatus . 158 PIG. PAGE. 6. Whirlwig ( Gyrinus) . 159 6. Helophorus aquaticus ... 162 7. Hydrophilus piceus . 162 PLATE XI. 1. Ranatra seizing its prey 176 2. Caddis - fly ( Leptucerus uiger) . 163 3. Caddis-case of sand . 165 4. Do. of erass . 165 5. Do. of leaves and sticks . 165 6. Do. made of small shells . 167 7. Do. do. 167 8. Do. of fir-leaves . 167 9. Ranatra . 175 10. Pupa of Caddis-fly . 168 11. Caddis-fly ( Fhryganea grand's ) . 163 12. Larva of Caddis-fly . 169 13. Do. of Dragon - fly (Agrion) . 170 14. Do. of Dragon - fly (Libellula depressa) ... 169 PLATE XII. 1. May - fly ( Ephemera vulgata) . 172 2. Larva of do . 173 3. Water Boatman ( Noto - necta lurcata) . 174 4. Water Scorpion ( Nepa cinerea) . 175 5. Drone-fly . 180 6. Stratiomys chameleon ... 179 7. Gnat (Culex pipiens) . 177 8. Water-measurers . 177 9. Cypris . 181 10. Water-flea ( Daphnia ) ... 181 12*} Cyclops . 182 13. Dragon-fly . 170 14. Dragon-fly quitting the pupal shell . 171 THE FRESH AND SALT-WATER AQUARIUM. - *o« - INTRODUCTION. IN the mythology of every land, the innate curiosity of the human mind betrays itself. Whether we take the ancient tales of Greece or Rome ; whether we decipher the hieroglyphs of Egypt ; whether we revel in the fanciful romances of the glowing East, or are enchained by the stern, yet not less poetical legends of the frozen North ; we find that the prominent idea is the insatiable desire of possessing hidden knowledge. In some few instances this ruling passion aspires to the spirit of prophecy, but in nearly every case is con¬ tented with its present sphere, and only seeks for a more extended knowledge of the material universe, its riches and its capabilities. Sometimes the fortunate hero is enabled to soar through the air ; he ascends to the skies, and learns the secrets of the stars. Sometimes he penetrates B 2 THE FRESH AND SALT-WATER AQUARIUM. to tlie central chambers of the world, anoints his eves with magic salve, and the treasures of earth are unveiled to his cleansed vision. Sometimes he enters into alliance with the semi-spiritual beings that people the elements, and becomes a temporary partaker of their privileges. Perhaps the deities of the sea claim affinity with him, and carry him down into the ocean depths ; where, with the nobles of the sea and their attendant Nereids, he holds strange festivals in submarine palaces. Perhaps the Naiads of the river become enamoured of him, decoy him beneath the waves which they rule, and keep him a very willing prisoner in their mysterious home, enchained by their beauty, and forgetful of his earthly love. In imagination we follow their adventures, speed our course through the sky, sink into the earth, or traverse the waters, and picture to ourselves the wonders which such privileges would reveal to us. “ Methought, I saw a thousand fearful wrecks ; A thousand men that fishes gnawed upon ; Wedges of gold, great anchors, heaps of pearl, Inestimable stones, unvalued jewels, All scattered in the bottom of the sea.” Specially does imagination revel in the depths of ocean, and disport itself among the caves of ocean, paved with gems and pearls, hung with living tapestries of sponge and seaweed, and peopled with strange, weird shapes, that crawled upon its INTRODUCTION. 3 sides, or bright glittering fishes, that darted through its portals. Thanks to modern inventions, many of these hidden wonders are now disclosed, and the curious inquirer can see these beings without the assistance of either Nereid or Naiad. Some of these wonders will be described in the following pages, and those who will endeavour to search for themselves will find that not even the vivid pages of fairy lore could picture beings of stranger aspect, or endow them with more singular power, than may be seen in a few gallons of water while we sit at ease in our own rooms. We need not take the trouble to descend in a diving-bell, nor fit on our head the diver’s enormous helmet ; for we can find in a small vessel of salt or fresh water enough to give us occupation for many a long year, and to disclose to us many of the secrets of nature. In the following pages I shall endeavour to show how any one can penetrate into the wonders of the deep, and can, in the seclusion of his own room, studv the manners and customs of the inhabitants of the waters. The history of aquaria is quite recent, but in the few years of its existence it displays many of the characteristics of more important histories, and lias its origin, its rise, its decadence, and its renovation. Some years ago, a complete aquarium mania ran through the country. Every one must needs have an aquarium, either of sea or fresh water, the former being preferred. B 2 4 THE FRESH AND SALT-WATER AQUARIUM. There were grand etymological discourses in the learned papers respecting the correct name which ought to be given to it. Some called it vivarium, but were met by objectors who said the Zoological Garden was equally a vivarium, and so was a dog- kennel or a stable. In order to meet the difficulty, they proposed the word aqua-vivarium — a word which certainly had the advantage of being correct, but the disadvantage of being complicated. Then came others who preferred the name aquarium, and straightway this name was adopted by common consent. It is true that exact linguists rejected the word, citing the Latin dictionary, which states that aquarius was either a water-bailiff, a water¬ man, or “ the man who carries the watering-pot ” in the Zodiac. Still aquarium is a simple and easy word, and entirely superseded aqua- vivarium, just as in a later year the word telegram super¬ seded telegrapheme. The fashionable lady had magnificent plate-glass aquaria in her drawing-room, and the schoolboy managed to keep an aquarium of lesser pretensions in his study. The odd corners of newspapers were filled with notes on aquaria, and a multitude of shops were opened for the simple purpose of supplying aquaria and their contents. The feeling, however, was like a hothouse plant, very luxuriant under artificial conditions, but failing when deprived of external assistance. Perhaps the beautiful plate-glass aquarium fell PlATE I. INTRODUCTION. 5 to pieces, discharged several gallons of sea-water over the fashionable carpet, and covered the fashionable furniture with sea-anemones, crabs, prawns, and other inhabitants of the waters. Or some of the inmates died, and the owner was too careless to remove them. Consequently they were left in the holes to which they had retreated, and in a few days they avenged themselves for the neglect by rendering the water so fetid that no one with ordinary sensibility could remain in the room. The schoolboy was very careful of his aquarium for a time, but in a month or two became tired of the constant attention required for its maintenance, and so gave it up. So, in due course of time, nine out of every ten aquaria were abandoned ; many of the shops were given up, because there was no longer any custom ; and to all appearance the aquarium fever had run its course, never again to appear, like hundreds of similar epidemics. But there was one element of strength in the aquarium possessed by none of the others. This was the study of Nature in one of her hitherto unstudied phases. Those who merely treated the aquarium as a toy soon became tired of it, and cast it away accordingly, but those who saw its real capability became more enamoured of it daily. Now, therefore, the number of aquaria is not nearly so great as was the case some years ago, but those that are in active existence are properly tended, G THE FRESH AND SALT-WATER AQUARIUM. and the teachings carefully learned. As I hope that many of my readers will desire to establish and to maintain aquaria, both of fresh and salt¬ water, I will give a few hints as to the stocking and managing them. Now, in the first place, the very name of Aquarium terrifies many, especially those who are unversed in its easily-solved mysteries. The very name seems somewhat pretentious, and the popular idea of the aquarium is quite consonant with such an idea. The word aquarium suggests an expensive structure of plate-glass, shining metal, and elaborate rockwork, tenanted with rare actiniae, strangely- shaped Crustacea, and gorgeous fishes, and decorated with seaweed of light green, dark purple, and rich scarlet. Of course, it is perfectly possible to have such structures, and to fill them with such inhabitants ; but for all practical purposes there is not the least necessity for either the elaborate vessel or the costly inmate. After an experience of some twelve years, I am disposed to multiply the vessels rather than to expend money in animals ; and have found that the simpler a vessel can be, the better it is for an aquarium, provided it fulfils certain conditions. There are two forms of vessels which are generally offered to the public, and both of them are about as bad as bad can be. The one is a deep, oblong vessel made of plate-glass, with a metal bed and metal framework. Set a pack of playing-cards INTRODUCTION. 7 on its edge, and there is the precise shape of the aquarium generally sold in ordinary shops. This being rather expensive, many persons demur at its price, and are then offered the ordinary gold-fish globe, or an improvement thereon— a vessel that, looks like a glass bell standing on its head, and fixed into a wooden pedestal. I shall now proceed to show why these forms are entirely wrong ; and then describe a variety of shapes which are well adapted to the purpose, and which are equally easy to be obtained and cheaply to be purchased. In the first place, all glass vessels have one radical error : they admit too much light ; and, as a general rule, the creatures which inhabit the water are not lovers of light. Many of them lurk unseen in holes, or under stones, or among roots ; and even those which do show themselves boldly are always glad of darkened places of refuge, whereto they can fly when alarmed. Vessels wholly made of glass afford no such privileges, and therefore the inhabitants are often sadly incon¬ venienced, and in many cases die, simply because they are worn out by want of repose. Moreover, as if the poor animals were not sufficiently worried, the aquarium is often put on a table or stand, and placed exactly in front of a window, so as to have as much light as possible upon it, and to have the water warmed by the direct rays of the sun, until the miserable inmates are half-killed with the heat and totally dazzled by I 8 THE FRESH AND SALT-WATER AQUARIUM. the light. Such an excess of light is injurious in another sense, especially in marine aquaria, because it encourages the growth of conferva and seaweed to such an extent that they become a positive nuisance, instead of a useful accessory. The form of the ordinary-shaped tanks is quite wrong. They certainly hold a large quantity of water, and therefore are thought fit to contain a large number of inmates. But it must be re¬ membered that fishes, and other inhabitants of the waves, exhaust the water by their respiration quite as much as we exhaust air. If you put a quantity of fishes into a small and deep vessel full of water, some will die in a very short time, and only a few hours will elapse before all will have perished. It is therefore as absolutely necessary that the abstracted oxygen should be restored to the exhausted water, as that the atmo¬ sphere of a crowded room should be replenished with fresh air. In consequence of this necessity, various plans for aeration were employed by aquarium-keepers. Ingenious pumps were attached to the tanks, by means of which streams of air were forced through the water. Some persons employed syringes, filled them with water, and squirted the water into the tank with such force as to carry a quantity of air among the inhabitants of the aquarium. Others were content with taking up some of the water and letting it fall back with a splash, so as to produce the same result. INTRODUCTION. 9 Now, all these proceedings were absolutely neces¬ sary, on account of the shape of the tank, and the stillness of the water. Many marine creatures, such as certain Crustacea, molluscs, and sea-anemones, live close to the shore, and are accustomed, not only to be left dry during extreme low water, but to have the spray dashing about them twice a day, as the advancing tide breaks over the rocks or sand. But the very form of the common oblong tank opposes itself to both those conditions. It is so deep that a perfect stillness reigns, and presents so small a surface to the air that there is no chance of oxygenizing the water except by artificial means. Water absorbs the oxygen of the air with won¬ derful rapidity, and if a sufficient surface be exposed, it will absorb enough to supply the wants of re¬ spiration for a goodly number of inhabitants. Were it not for this fact, the fishes in a pond would soon die for want of oxygen. It will now be seen that an aquarium which is to fulfil, as far as possible, the same conditions as the river, the pond, or the sea, ought to be as wide as possible, so as to present a large superficies of water to the air. Moreover, it must not be made of a transparent material, such as glass, but its sides ought to be opaque, except in front ; and the front should not be turned towards the window. Should the reader happen to possess one of these ordinary tanks, he can vastly improve it by covering the back and the ends with thick pasteboard, so that 10 THE FRESH AND SALT-WATER AQUARIUM. the light is shut out, and the pasteboard can easily* be removed for the purpose of inspecting the interior of the tank. But there is no need whatever for a complicated glass tank, which is so deep that the owner finds great difficulty in getting at the various objects, and is too heavy to be moved, and occasionally apt to worry its owner by a sudden disposition to leak. Any kind of tub or pan will do for an aquarium, provided that the owner cares more for the inmates than the appearance of their dwelling. I have now at my side a common earthenware pan, eighteen inches wide, and three deep, in which are flourish¬ ing half a dozen sea-anemones, two kinds of sea¬ weed, and a number of purpura and other common shells. A crab lived in it for a considerable time, and would probably have been alive now but for a singular misfortune. One evening, before the lamps were lighted, I was coming up the stairs to my room — it is situated at the top of the house ; and upon the third stair from the front door I trod upon something, and crushed it. On bringing a light and looking to see what strange object could have been on the stairs, T was equally surprised and sorry to find that it was my little crab. It was all but dead, and recovery was hopeless. The fact was, that I had forgotten to cover the pan, and the crab must have clambered up the side, and, hitching itself on one of the shells, got out of the pan and. INTRODUCTION. 11 traversed the room. But how the creature con¬ trived to get out at the door of my room, and make its way down two flights of stairs and along a landing, is a mystery which I cannot solve. I was the more sorry because the creature had learned to overcome its first dread of a human being, and, instead of scuttling under a stone when I approached, remained quite unconcernedly on the top of an ulva-covered flint, or crawled leisurely over the bottom of the pan. At first it was sadly discomfited at its inability to burrow ; the yellow colour of the pan evidently giving it the idea that it was upon its accustomed sand ; but it soon gave up the attempt, and seemed quite reconciled to its prison. In this primitive tank there are some flints, with a little ulva and enteromorpha adhering to them. I had some with specimens of the ocean barnacle ; but as the creatures declined to live, the stones were . removed. As to the anemones, they have chosen to fix themselves so tightly in an old pomade pot in which they were conveyed to my house, that I have not disturbed them. Of course, in a vessel of this kind, the loss of water by evaporation is very rapid, and must be repaired by constant supplies of fresh water. There is not the least difficulty in adding the needful water, nor need it be distilled, as is stated h7 some aquarium-keepers. I simply use soft water, taking care that it is clear, and pour it 12 THE FRESH AND SALT-WATER AQUARIUM. into the pan without any precaution. I do not pour it upon the anemones, because the fresh water might fill the jar in which they have sta¬ tioned themselves, and so damage them seriously. Otherwise, I just pour in the water, and let it mix itself as it likes, without stirring it or doing any¬ thing to disturb the inmates. Once or twice, when I have been away from home for a day or two, the evaporation has been equal to nearly one-third of its amount, and the remaining fluid formed, in consequence, an ex¬ ceedingly concentrated solution of marine salts. The inhabitants did not like the state of things at all. The shells were all out of the water, and the anemones much contracted, although the tips of their tentacles protruded. When the fresh water was added, they withdrew the tentacles entirely, and made themselves as flat as they could ; but in an hour they had recovered them¬ selves, and were waving their long tentacles in all their beauty. If the young observer is lodging at the sea-side, let me advise him to set up — not one large aqua¬ rium, but a series of pans, previously taking care to propitiate the landlady, who is sure to offer very forcible objections to such articles. Get a glazier to cut glass covers for your pans, or the inmates will escape, and the pans be filled with dust. We will now proceed to a short description of INTRODUCTION. 1 ° the various vegetable and animal inhabitants of an aquarium, and will begin with the simplest ; namely, the Seaweed. There are many species of seaweed, which are either pretty in colour, graceful in form, or im¬ posing in appearance, which can never be kept in an aquarium. Not only will they die with great rapidity, but they cause an ugly appearance in the tank, giving out slime and other unpleasant substances, and often producing an odour pecu¬ liarly abominable, which cannot be easily described, but which, when once smelt, is never forgotten. As a general rule, the young aquarium-keeper may reject almost every seaweed that he finds, and to this rule there are but a very few excep¬ tions. He may think it rather hard to be obliged to do so, because some of them, especially those belonging to the red division, are so pretty that they are for a time extremely ornamental, while others are so elegant or so curious in shape, that it is, at first, very hard to resist the temptation of placing them in the tank. Such, for example, is the Delesseria, whose fronds mav often be found on the shore after a gale, having been torn from their attachments by the waves. It is so elegant in shape, and so lovely in colour, that even an experienced aquarium-keeper can seldom pass it, as it lies on the shore, without picking it up and admiring its exquisite fronds, so delicate in struc¬ ture, and so leaf-like in form. Nothing looks 14 THE FRESH AND SALT-WATER AQUARIUM. better in an aquarium for a clay or two ; but then its beauty fades, the frond becomes paler in spots, then is ragged at the edge, and finally breaks up into fragments. So it is with the curious coral¬ lines, with their strange chalky skeleton ; and so it is with the whole of the red seaweeds, in spite of their enticing beauty. As to the brown varieties, many of them are so large that they could not be placed in any ordinary tank, but there are some which are small enough to find space, and curious enough to induce a be¬ ginner to place them in the aquarium. Such, for example, is the strange-looking Padina, whose fan-like fronds, with their regular dark bands, are not very frequently found on our coasts, except those of the extreme south. Some years ago, however, I observed a large colony of the Padina growing upon a ridge of rocks running seaward from Foreness Point, at Margate. Every visitor to this place knows the rocks, dark with their heavy cover¬ ing of seaweeds, that project into the sea, and are left bare at low water. Through these rocks run, INTRODUCTION. 15 at various intervals, certain channels which are free from the bladder-wrack, and other large algae, with which the rocks are so thickly clothed, and which serve to conduct the waters of the receding tide back to the sea. One day, at very low tide, when wading along one of these channels, I saw a long ridge of some kind of algae, different from those species which were most prevalent, but, owing to the ripple caused by a sharp breeze, could not discover what it was. On gathering it I was surprised to find that it was the Padina pavonia itself — just the very last species I should have expected to find at Margate. One might hope to discover many of the more hardy species, but to find an alga which is mostly confined to the extreme south, off the Margate shore, which lies open to the north wind and gets the full benefit of it, was a circumstance which could hardly be expected. 16 THE FRESH AND SALT-WATER AQUARIUM. CHAPTER I. ALGiE OR SEAWEEDS. THE green varieties of algae are most easily kept, and the very "best of them is, fortunately, the most plentiful. This is the Ulva latissima (Plate 1, fig. 4), whose broad green, ribbon-like fronds are to be found in abundance. It is popularly known as Green Laver, because, when gathered and stewed down slowly, it is reduced to a gela¬ tinous substance which is called laver. The laver is said to be extremely nutritious, like the Carra¬ geen or Irish moss, which also grows in abundance on our coasts, and by some persons is very much liked. An allied species, which will be presently mentioned, is employed in the same manner. The green laver is sometimes called the sea-lettuce, on account of the shape and colour of its fronds. There is no better alga for an aquarium than the green laver. The reader will remember some remarks upon the mode of supplying oxygen to the water, and the trouble which is sometimes i involved in performing that operation. Now, the ulva saves much of this trouble, and by its own ALGJ3 OR SEAWEEDS. 17 respiration takes from the water those elements which the water does not require, and supplies those which it needs. If a frond of ulva be placed in some sea-water, and set in a tolerably light spot, a most beautiful appearance will be presented. The entire surface of the frond will be covered with minute bubbles of air, looking as if diamond dust had been scattered over it. By degrees these bubbles enlarge, then coalesce together, and finally are detached from the plant and float to the sur¬ face. If the contents of these bubbles be gathered together and examined, they will be found to con¬ sist chiefly of oxygen gas, just the very element of which the animal inhabitants deprive the water by their respiration. The plant, in its turn, requires the elements exhaled by the animals, and so the circle of nature completes itself. If the aquarium-keeper would like to test the quality of this gas himself, he can do so in a very simple manner. Let a bottle be filled with water, and then placed, mouth downwards, in the aqua¬ rium. The mouth of the bottle should then be held over the leaves, and the bubbles touched with a small stick or wire. They will then become detached, and will rise into the bottle, displacing their own bulk of the water. When all the bubbles are collected, the stopper is placed in the bottle, while it is still under water, and the bottle can then be removed with its contents. There is no necessity to have a large quantity of o 18 THE FRESJI AND SALT-WATER AQUARIUM. these algce, and, indeed, there is no absolute neces¬ sity to have any algae at all, if the vessel is wide and shallow, as has already been described. More¬ over, if the conditions should be favourable, the multitudinous spores will settle themselves on the stones or sides of the tank, and will cover them with a soft coating of minute algae, which will serve the double purpose of looking pretty and aiding in regenerating the water. The more light that is admitted, the faster will these spores de¬ velop themselves, and it is often necessary to keep a sponge fixed to a handle for the purpose of keep¬ ing the glass front of the aquarium clear from these tiny settlers. Another useful alga is the Purple Laver (Por- phyra laciniata). In form this species bears a close resemblance to the green laver ; but it is very different in colour, being dark¬ ish purple instead of green. In some parts of this coun¬ try it is much eaten, being cooked in the sam e manner as the green laver. In Ire¬ land it forms a fa¬ vourite article of Chondrns crispus. food, and in maDy places is always cooked and brought to table in a ALG^E OR SEAWEEDS. 19 silver saucepan. When cooked, it is popularly called “sloke.” As we are on this ground, I may mention that two more edible seaweeds are plentiful on our coasts. One is the Carrageen ( Chonclrus crisp us)* which is often known under the name of Irish moss, and which, when reduced by boiling to a gelatinous consistency, is mixed with tea and coffee, or some¬ times eaten by itself as jelly. This alga is very com¬ mon, and any quantity may be gathered in an hour. It is extremely variable in colour, the hues differ¬ ing according to the locality and depth of water. Generally it is dark green, with a tinge of yellow near the edges ; but, in deep water, the yellow hue is not developed, and, in consequence, the frond assumes a purplish tint. Light seems to produce the yellow colour ; for in specimens that grow in the pools near high-water mark, and which, in consequence, are much exposed to the direct rays of the sun, the colour is greenish-yellow, the latter hue predominating. When washed in fresh water and well dried, it becomes almost horny in texture ; and when macerated in hot water, it dissolves like gelatine. This gelatinous substance is, by the way, admirably adapted for fastening dried seaweed to paper. In most marine algae there is a sufficient amount of this vegetable glue to make them adhere to paper as firmly as if paper and alga were one substance. # See also Plate I. fig-. 2. 20 THE FRESH AND SALT-WATER AQUARIUM. But there are several species that will not adhere without external aid. Y arious materials have been employed for the purpose ; such as gum, isinglass, and liquid glue. But there is nothing which really answers the purpose so well as gelatine made from the Irish moss. This species can be kept in an aquarium, if care be taken. But it is large, occu¬ pies much space, and is certainly not rare enough, nor handsome enough, to be worth the trouble. The last species of edible seaweed which will be Iridea edulis. mentioned is theDulse or Dillosk, a species which is found on many of our coasts, and which is very plen¬ tiful in some localities. Itsform is giveninthe illustration, and its colour is a deep, dark red. It derives its name of Iridea from the iridescent hues vhich play on its surface when sub¬ merged, and which change with every movement of the plant or of the spec¬ tator. The dillosk is a favourite article of Plate III. ALG.E OR SEAWEEDS. 21 food in many places, especially on some of tlie coasts of Ireland, where it is eaten both raw and cooked. Some persons are so extravagantly fond of it that they always have it served up for breakfast. The taste, however, seems to be an acquired one, and it is certainly one which I never could acquire, though I have given it a fair trial. Perhaps the taste for dillosk is like that for olives, and comes naturally to some persons, while others find themselves unable to perceive any gratification in eating either the one or the other. Among the green seaweeds that may be kept in an aquarium may be mentioned the very prolific Cladophora arcta. species which is scientifically termed Cladophora 22 THE FRESII AND SALT-WATER AQUARIUM. arcta. This is by no means a pretty species when taken from the water, though it is handsome enough when submerged.* But, to the seaside observer, it is one of the treasure-houses of the deep. Should the reader of these pages like to go to the seaside and examine for himself, let me recommend one excellent plan. Mark out a small tract of shore, say fifty yards wide, and work it thoroughly. Off with such im¬ pediments as respectable shoes and stockings ; but put on an old pair of shoes, with tolerably stout soles, or you will find that wading is not so pleasant a process as it looks. There are sharp stones ; there are limpet shells, which cut the feet whichever way they may be lying ; there are the acorn barnacles, which render the walking as agreeable as the celebrated journey with peas (unboiled) in the shoes ; there are mussels, which make the unlucky wader think that he is walking over a road com¬ posed of broken bottles ; there are sharp splinters of wood, and, in fact, everything that makes the wader look to his footsteps, and not to the inhabi¬ tants of the sea. The area being rigidly marked out, let every square foot be carefully examined, beginning as soon as the receding tide will allow the inhabitants of the. water to be seen, and con¬ tinuing until the waves begin to return on their endless track. Look into every crevice, examine # Another species, Cladophora pellucida, is shown at Plate I. fig. 3. ALGyE OH SEAWEEDS. 23 each projecting angle of rock, turn over each loose stone, lift up each bunch of seaweed, and pick up every shell that you come across. Do not be dis¬ heartened at the slowness of the process, for it is the only method of working a locality thoroughly. At first it is rather tedious work, simply because the eye is not accustomed to notice those minute details on which the whole science depends. Unless trained in this careful manner, the eye is sure to miss little points which speak volumes to the ex. perienced naturalist, but which a novice can hardly see at all, and, if he does see, cannot understand. In a few days the improvement will be perceptible,, even to the observer himself, and he will find that he is taking notice of minutiae which before would have escaped observation, and which, although they appeared trifling, are as valuable to him as a nibbled grass-blade, or a leaf turned the wrong way, to an Indian tracker. The Cladophora is just one of those very objects that well repay a close examination. You will neither have time for useful examination while still wading, nor will you be able to stoop for so lengthened a period as would be required. Look out for a good thick bunch of the Cladophora, puli it up gently at the root, and transfer it to a pail or similar vessel. Do so until the pail is full, and postpone the examination until you reach home. There have a large empty basin, and a plentiful supply of sea-water. 24 THE FRESH AND SALT-WATER AQUARIUM. Pour a quart or so of water into the basin ; pick off a small tuft of the Cladophora, and put it into the water. Although it clings so tightly together while in the air, no sooner does the alga find itself in water, than it spreads itself out, and all the little branchlets are supported by the liquid. Now, shake each tuft in the water, and separate the fibres, and you will be tolerably sure to find among the green foliage some of the smaller animals which inhabit the ocean, star-fishes and Crustacea of dif¬ ferent kinds being the most plentiful. The last of the seaweeds that will be mentioned is the Bryopsis plumosa (Plate 1, fig. 6), a singu¬ larly elegant little species, for which I very much regret there is no popular name. Its colour is very light green, and, when growing, it has the appearance of green feathers set on slender stalks. Being an annual plant, it can only be found during certain seasons of the year, such as summer and autumn. In proportion to its size, it has a large amount of gelatinous substance, and adheres well to paper. FISHES. 25 CHAPTER II. FISHES. HAYING- placed the seaweed in an aquarium, the next step is to stock it with living inhabi¬ tants. Of the dwellers in the sea, the fish take the first place, and will therefore be mentioned first. The number of species found on our coasts is so great that only a very few can be mentioned in these pages. As the size of some of these unfits them for residence in the limited space afforded by an aquarium, I shall therefore only mention a few of those which have actually been kept in an aquarium, and which have some peculiarity that is worthy of notice. Perhaps the reader may ask how the fish in question are to be caught, inasmuch as the sea is rather a wide place, and means of capture are limited. It is evident that the hook is not a de¬ sirable instrument, and that it must therefore be laid aside whenever the fish are wanted in a perfect state. The net, in one or other of its 26 THE FRESH AND SALT-WATER AQUARIUM. forms, is the only implement that is. really ser¬ viceable ; and this must be modified according to the locality, and the particular fish which is to be captured. Some species, for example, are seldom, if ever, seen in deep water, preferring to hang about the rocky shores, to frequent the sandy coasts, or to haunt those spots where the zostera waves its long narrow blades, like a submarine hay field just ready to be mown. Some, on the contrary, never trust themselves to the shallow water, and are only to be captured at a depth of many fathoms. Most of these, how¬ ever, may be found within a mile or so of the shore, according to the slope of the sea-bed, the consequent depth of the water, and the particular sorts of seaweed which grow in the locality, and which furnish retirement to the marine animals on which they feed. Of all the varieties of nets, those which are most useful for the owner of an aquarium are the hand- net, the trawl, the dredge, and the keer-drag. The first of these nets is really very useful, and will enable a skilful handler to capture many kinds of little fishes that are left in the rock-pools when the tide has receded : gobies, gunnells, pipe-fish, and the like, being the usual inhabitants of such pools. The trawl, in places where it can be used, is simply invaluable, as it sweeps into its treacherous mouth all kinds of animals, including many species of fish, and creates a positive embarrassment of riches to FISHES. 27 the trawler. The dredge, though it is mostly em¬ ployed in procuring molluscs and Crustacea, is extremely useful in the capture of fishes, which, in spite of its small size, are frequently found in it. The keer-drag is a modification of the dredge, but has a very long net, with an arrangement which allows the fish to enter, but prevents them from retreating. As to small flat-fish, such as dabs, flounders, &c., nothing is better than the common shrimp-net. If the reader does not object to getting wet, he cannot do better than walk through the sea with a shrimp-catcher, and give him some remuneration for taking a choice of the contents of his net. It is useless to ask him to take the shrimps and prawns, and put all the other creatures in a sepa¬ rate net. He will not do it. He has such an inveterate habit of throwing away everything that is neither a shrimp nor a prawn, that he mechani¬ cally empties into the sea the very creatures which are most required. In most cases, he does not recognize a vast number of animals to be animals at all, but classes them with seaweed and stones, and other “rubbish.” The first fish in our list is the common Basse ( Labrax Lupus), which is closely allied to the fresh-water perch, and which, in fact, looks very like an ordinary perch that has contrived to escape from the river into the sea. On some of our coasts 28 THE FRESH AND SALT-WATER AQUARIUM. the Basse is called the Sea Dace. As, moreover, this fish is somewhat tolerant of fresh, or, at all events, of brackish water, the two species might easily be confounded together. It has even been transferred from the sea to an inland lake, and has been rather improved than deteriorated by the change. This hardiness of nature causes it to be an admirable tenant of an aquarium, where the daily conditions of life are so unlike those to which the inmates are accustomed when in the enjoyment of freedom. It is essentially a shore fish, finding all its food within a very short distance of the land, and being nearly as bold as its fluviatile relative. It is par¬ ticularly fond of the Onisci, or Sea-slaters ; and when the wind is high, and the waves are dashing on the shore, the Basse ventures quite close to the rocks, for the purpose of picking up the unfortu¬ nate slaters, as they are washed out of the crevices in which they hide themselves by day. The Basse may be caught like the Perch with a rod and line, and bites most freely during the last portion of the flood-tide. A long jetty like that of Margate is a good spot wherein to angle for the Basse as well as for other shore-loving fish ; they seeming to be attracted by the smaller marine animals that haunt the piles on which the structure is supported, or by the debris that is usually thrown in the water. Sometimes it is taken with a very simple kind of net, resembling a FISHES. 29 seine on a very small scale. This net is taken in the water by two men, who wade as far as they can, and then separate, each taking an end of the net. When they have stretched it, they walk slowly ashore, bringing with them the fish entangled in the net. Smelts are taken in the same manner in the Medway and other localities which they favour with their presence. 