Sea and River-side Rambles in Victoria/Chapter 9
CHAPTER IX.
THE AQUARIUM.
There is something highly satisfactory to the Naturalist in the reflection that science has taken rapid strides within but a few years, and in no department more so than in Marine Zoology,—here, where but a brief period back all was little better than conjectural, there is now ocular demonstration, not only of the many creatures inhabiting the ocean, the one dependent on the other, but also of their habits, minute structure, and mode of living. From our childhood up we had been accustomed to see and have Gold and Silver Fishes in globular glass bowls, but the pleasure was in almost every case a temporary one, the inhabitants dying from the exhaustion of that free oxygen which had existed in the water, but which had all been absorbed, and its place taken by carbon, — before a fresh supply could be given by renewing the water. Collectors have long had their glass bottles wherein to convey to their study such creatures as they desired more nearly to cultivate the acquaintance of, but here too the duration of life was but brief, and soon they had to be transferred to a bottle of Goadby if their preservation was an object. No wonder then that it became a matter of such importance to obtain the means of preserving in health and brilliancy of colour such creatures as we wished to cultivate, and with whose economy we were almost entirely unacquainted. How this could be achieved, was a matter for long and untiring experiments and trials and repeated failures. But Chemistry was at last applied to the case, and instead of the troublesome operation of perpetually changing the water, ever in dread that a case similar to that we have quoted above might occur, the long sought end was attained; by what is called compensation, animals may be kept alive for an indefinite period,—viz.: by thoroughly understanding the relations between animal and vegetable life on the principles of Priestley, followed up by Ingenhouss, and "finally adapted to the present purpose by Mr. Ward, the inventor of the glass cases which bear his name, Johnston, the learned author of Histories of the "British Zoophytes," "Sponges," &c, Warrington and Gosse. It was Mr. Bowerbank, however, who gave the hint to the Secretary of the Regent's Park Gardens, from which arose the beautiful tanks which are now in full operation there. We have often before had this process of respiratory interchange explained, but who has brought it so vividly before us, as our often quoted friend and companion (his charming writings have made him so,) Mr. Lewes. "Let us stand apart," he says, "and contemplate this marvel no longer as an animal function, but rather as a planetary phenomenon; let us endeavour to picture to ourselves the silent creative activity everywhere dependent on this interchange. The forests, the prairies, the meadows, the cornfields, and gardens,—the mighty expanse of plant-life covering mountain and valley—these subsist on the carbonic acid which is exhaled from the lungs and bodies of animals. Plants take up this carbonic acid from the atmosphere, mould the carbon into their own substance, and set free the oxygen, once more returning it to the atmosphere. Animals reverse the process, taking up the oxygen, and giving out carbonic acid for the nourishment of plants," and so as Keats beautifully says,—
"Keeping up an interchange of favours
Like good men in the truth of their behaviours."
It is to the want of an acquaintance with these first principles that so many of the failures in attempting to form Aquaria may be attributed; the mere filling them with animals will not suffice,—and secondly to an abominable system of overstocking,—specimen after specimen dying from an insufficiency of those gasses which are essential to life.
How this necessary balance may be attained, we shall endeavour to show as we progress,—meanwhile we can go in detail through the various matters required for the establishment of an Aquarium. Its form must depend very much on the taste or caprice of the owner; the square one with glass sides is perhaps the most common, but we question whether it is the most desirable, for Mr. Warrington has discovered that it is absolutely necessary the sun's light should fall directly from the surface—on those Algae, which have been removed from the deeper recesses of the ocean, where they were but partially exposed to light, to ornament the tank and afford sustenance to its inhabitants. The tank used by this gentleman is four-sided,—the back and sides being composed of slate,—the back gradually sloping upwards from the bottom at an angle of 50 degrees. By this plan not only does the light fall directly from the top, but the water more freely absorbs atmospheric air. This object is also attained by staining a portion of the glass placed next the light of a sea-green,—a plan adopted successfully by many practical keepers of Aquaria in England.
Were we to decide, we should prefer the form suggested by Mr. Shirley Hibberd, in his very concise little Work on the "Aquarium," viz., that of the double cube, the length of the tank being just double its width and depth, so that if cut into two equal parts two cubes would be formed. The glass should be set in grooves in the slate, and bound outside with tastefully turned pillars of wood, or any other substance which can easily be obtained or may suit the whim. White lead putty may be used for cementing, but to prevent the water being in any way poisoned by the lead, a coating of shell-lac dissolved in naptha, and made into a paste with whiting, must be laid over it.
The formers of Aquaria are generally in too great a hurry to set their tanks going, but much trouble and very considerable disappointment, not to say expense, (where the party lives away from the seashore, and may have to depend for supplies of stock on some zealous friends, or those, if there are any such, making it a means of livelihood,) would be saved, by allowing water to remain in the tank for several days at a time, changing it occasionally, so as to sweeten the tank before commencing operations,—and even then go gradually to work. First, then, there should be a bottom of good sea-sand (not too finely disintegrated) and pebbles laid on thickly, as many fishes, Crustaceans, Molluscs, and other creatures love to burrow in it, and besides, it contains a host of minute atoms which will afford sustenance to some one or the other of our pets;—this layer having well settled down, now comes a matter involving much taste,—the formation of rockwork,—not such fantastical grottoes as we have observed in some Cockney Aquaria, but certain nooks and crannies wherein those which delight in seclusion may ensconce themselves. The shore at Geelong affords abundant material in densely clustered masses of Serpulæ adhering to the stones, fragments of which may easily be detached with a good hammer such as we have already described,—this, while ornamental, adds thousands of interesting and graceful inhabitants, whose elegantly fringed cilias will be protruded the moment they feel the water, and about St. Kilda and similar places along the coast, scarcely a stone can be taken up that is not covered with the lovely Lepralia or Sea-scurf, minute eggs, &c., so it will only require prudent arrangement, without crowding, which in a tank of small dimensions is undesirable, as not only does it render the detection of dead or dying animals a matter of difficulty, but by displacing a certain portion of water, the animals are to some extent robbed of the means by which they should be supported.
When the tank is covered by one of the elegant domed lids which we have occasionally seen, and which we recommend to exclude dust, and to preclude the escape of such creatures as, like ourselves, are given to roaming, the rock-work as we may term it, may project above the surface of the water, to allow such animals as desire it the means of gratifying' themselves. The author of "Ocean Gardens" suggests a kind of double Aquarium, and a contrivance by means of which a large portion of water should flow gradually from one tank to the other at fixed periods, in imitation of the ebb and flow of the tide. Many interesting phenomena he anticipates would thus be exhibited, such as the closing of the Sea Anemones (Actiniæ) as the water receded, and their expansion on its return;—this change too might be found highly advantageous to the health and development of those animals whose natural habitat lies between high and low water mark, and whose constitution is therefore framed to require entire or partial exposure to the air at certain intervals of time. A pretty idea, which we trust some of our readers may carry out.
Well now, these preliminaries being settled, we may add more water to the tank,—obtained wherever it is possible fresh from the sea, and if at all dirty, filtered through charcoal before being used. Densely populated as seawater is with minute animal life, it must necessarily be more conducive to the success of an Aquarium than that artificially made. Mr. Hibberd argues the question in this way, that in the latter, the very absence of organic matter is advantageous, since the water is less likely to get out of condition than the seawater, where the germs may decay and putrefy, spreading destruction in all directions,—nevertheless, give us seawater with life in as many of its infinitesimal germs as possible. We can by care guard against casualties, but we cannot always obtain specimens. Yet after all there are many who must resort to this artificial water, and so we give Mr. Gosse's receipt for it; giving some little hope in the experience of Mr. Hibberd,[1] that it serves all the purposes admirably, there being no diminution of vigour or beauty in the plants, or of gambolling playfulness in the animals. Strange, however, if such was his opinion in the book from which we have quoted, that only a brief time after in his "Book of the Aquarium," page 59, he states, how quite unsuited for animal life of any kind is this artificial seawater, until it has been brought into condition by means of growing weeds for eight or ten days, and for Crustaceans, Starfishes, and Fishes proper, it is not suitable till it has been in use for many months, and even then some species lose their health in it, and at last perish. These, however, are the constituents of the artificial seawater:—
Common Salt, 3½ ounces.
Epsom Salts, ¼ ounce.
Chloride of Magnesium, 200 grains (troy).
Chloride of Potassium, 40„„
or, according to Mr. Hibberd:—
| 15½ | Quarts Fresh River Water, (beer measure). |
| 14 | Ounces Table Salt, (avoirdupois). |
| 1 | „Epsom Salts, (ditto), |
| 800 | Grains Chloride Magnesium, (troy). |
| 160 | „„Potassium.„ |
This should be tested by the hydrometer until it reaches a specific gravity of 1·028, being that of seawater. And now we may enliven the appearance of the Aquarium, by adding some seaweeds preparatory to stocking it with such animals as may be most desirable,—nor is this portion of our operations lightly to be passed over, for on its proper regulation depends almost entirely success or failure. The collection of materials will afford much pleasure and healthy exercise, and when they are flourishing and spreading out their delicate fronds in the waters of our tank, we can recall with delight the rambles we had in search of them.
The green Seaweeds are the most desirable, not only as Dr. Badham remarks on account of their great beauty, but because they do not, like the red or brown kinds, render the water turbid by decomposition, and what a glorious selection we have on these shores!!—the feathery Bryopsis, looking under a microscope like spun glass, the ribbony Ulva, the green bullion-shaped tassels of Codium tomentosum, fringing the sides of the rock-pools— you will have to bare your arms to reach them,—the many varieties of Caulerpa, Enteromorpha,—the lovely Apjohnia lætevirens, which extends along the whole Southern coast,—the glassy Cladophora, with a host of others. In the use of Red Algæ, the experimenter must take his chance,—any way he must have many failures; but there is one, the Griffithsia, which Dr. Harvey recommends, and there is nothing to compare with it for beauty. The pools about Queenscliff, St. Kilda, Warrnambool, Armstrong's Bay near Port Fairy, Portland, and other of our Sea coasts, will afford abundance of specimens in addition to those already enumerated, which are the best to commence with, but in no case must they be used unless adhering to the rocks or other substances on which they may be growing, as otherwise they would rapidly decompose and render the water quite unfit for animal life. Some taste too may be used in this matter, for glass bottles, old boots, and sheep's skulls, not unfrequently form the basis of attachment. Olive seaweeds cannot be recommended, although in an Aquarium, which we very lately had the pleasure of inspecting, the necklace shaped Hormosira Banksii, was the special delight of a dozen or more young and old Hippocampi or Sea horses (p. 37), which twisted their tails around its chain-like vesicles, evidently quite at home.
The best test by far of the tank being in a fit state for the introduction of stock is, when small crystal globules of oxygen appear on the plants. This happy condition being arrived at, we may proceed,—and yet on second thoughts it is as well to know something of the mode of respiration of the aquatic animals, since that will be of sure service in making a selection for the tank. The lower animals should be the first chosen, for one very good reason, that their respiration is far less active than in those of a higher organisation, and this applies pretty generally to all creatures inhabiting the watery element; in them respiration is performed by branchiæ or gills, varying much in form, and by the air with which the water is impregnated; thus in the Fishes we observe the mouth frequently opened to admit the water, which passing out through the gills serves to oxygenate their blood; a fish on dry land does not die from any want of oxygen, but from being asphyxiated in consequence of the absence of that element on which the gills are dependent for a due performance of their functions; but this is not the same in all fishes, for in some (the shark for example) there are simple openings, varying in number to allow of the exit of the water, whilst in some where the operculum or covering of the gills is but narrowly cloven, a certain quantity of water is retained, by which they can continue out of their natural element for some considerable time, and even perform migrations overland, from one place to the other, and the Climbing Perch (Perca scandens), "quits the water and ascends the roots and branches of the Mangrove trees, an effort it accomplishes by using its ventral fins as feet."[2]
Of course we must to a certain extent be dependent on the part of the coast to which we may be near;—some neighbourhoods are poor in comparison with others, but there are hone so barren as not to afford abundance of live stock. We have already mentioned the lovely Terebellæ and Serpulæ, the Sea Cucumbers (Holothuriæ), the centipedal Nereis, the ribbony Planaricæ, pop them all in, and for Fishes, the tiny Hippocampus or Sea horse, the slender Pipe fish (Syngnathus), if there is room, are the most desirable; by all means have a Hermit Crab for his comical ways, and there are many others which may be experimented on, such as our Seaweedwearing friend mentioned previously in these pages, but there are some species which on account of their voracity must not be admitted; a few of the smaller Starfishes must go in, since they will quickly get rid of any decomposing substances: [they flock to the slaughter-houses on the Bay at Geelong, to feed on the debris there.] Agassiz has observed that the eggs of the Starfish, after they are laid, are taken up by the parent animal, and kept between its tubes below the mouth. The Starfish bends itself round them, surrounds the eggs with its suckers, and moves about with them. When the eggs have been removed to some distance, it has been noticed to go towards them, take them up again, and move off with them, showing that these animals so low in structure, and apparently deprived of all instinct, (if any animal can be supposed to be without it,) really watch over their young. A Sea-egg or two will be great pets. Of shells we should select specimens of the Fwus or Spindle shell, their bright red feet rendering them very attractive, as they crawl up the sides of the tank; the less rare Murex; Top shells or Turbo; Trochi or Hoop shells to keep down the confervoid growths which otherwise would dim the glass sides of the Aquarium, small Haliotideæ or Ear-shells; some of the Bonnet Limpets, the lovely gaudily-colored Aviculas; (Geelong), Chitons, and others which we cannot mention here.
With a small pocket lens, or with the Portable Microscope which Mr. Warrington has invented for the easier examination of living objects contained in glass bottles or Aquaria, not a day or an hour will pass without something new being discovered, fresh beauties coming to light, which will amply repay any labour or expense which may have been incurred, and we shall at once own the truth of the Poet's saying, that—
"Each drop of water is a world containing
Creatures more numerous than the men of Earth."
Before proceeding to treat of the Freshwater Aquarium, we may briefly mention a few matters—which, though apparently trifling, are yet essential to the success of the Marine tank, as also the well being of the inhabitants of it.
It has already been stated that it is quite unnecessary to change the water, but it may be well occasionally to aerate it by dipping up a small quantity and pouring it rapidly back into the tank, but even this is opposed to the true principles of "compensation," and need only be resorted to where the animals become sluggish, and the fishes find their way to the surface to obtain there what they should find in their own element. A small syphon of gutta percha or tin will be handy, should it be necessary to draw off or replace the water. The short end must be placed below the surface of the water in the tank, and the mouth applied to it until the water flows, which it will continue to do without further trouble so long as the short end remains under water.
It may so happen, (it is but human nature) that certain species do not dwell amicably with their mates, and others from some cause or the other (not at once apparent) may sicken,—in such a case, remove them without delay to small glass vases where they may be treated as circumstances require. The readiest mode of removing them to and fro is, by means of a small muslin or fine netted bag, attached to a long handle, (the small utensil used for poaching eggs will explain what we mean). We have grieved to see many fine specimens destroyed on removal, and this makes us give a few words of caution on the subject.
And now having a family about us, we must needs feed them, or we may have to appear before the Bench for maintenance;—"an unfortunate Hippocampus and fourteen little ones," or "a poor old crippled Starfish, (rendered blind by disputative authorities) and a family of orphans" would settle the matter unfavourably for us very speedily, in which event we should decidedly have to sue for a divorce a mensâ, to say the least of it; but most of the inhabitants find ample sustenance in the water, and for those which desire something more nourishing, a small portion of raw meat may be lowered by a string into the tank daily, so as to be withdrawn at will, and thus decomposition be prevented.
To remove or secure any small objects, a small glass tube of a diameter of about a quarter of an inch will be of service; to use it, the forefinger should be placed on the top, and the tube placed over the object, which, on the forefinger being withdrawn, will rise into it, and the finger being again applied, it may be removed in safety.
The formation of the Freshwater Aquarium will vary but little from that already described: a few inches of sand wherein the plants may root, and a few stones laid on it is desirable, but rock work is not necessary, in fact to our taste, decidedly objectionable and unsightly. Good well water, the experience of many writers has proved to be as well adapted to the purpose as river water, but the same caution that we recommended in stocking the Marine Aquarium should be observed here. Our readers will have frequently noticed the floating feathery green scum in our rivers attached to stones and pieces of wood, or the bottoms of boats,—this under the microscope displays forms as lovely as they are various, of what are scientifically called Freshwater Algæ; have some, by all means,—a small plant of the Damasonium—
"Its white canopies,
Upward turn'd to catch the heaven's dew!"
will be a prize, and its large lobed leaves will form a delightful shelter for many of the creatures we shall select for our tank,—the slender Crowfoot (Ranunculus inundatus) of our Melbourne lagoons and marshes, the pretty Myriophyllum of all the lagoons and sluggish rivers; small "pond weeds " Potamogiton, with the lovely floating Azollarubra or pinnata, soft as velvet, their tiny hair-like roots pendent in the water, are all desirable.
As for stock, it is scarcely necessary to give instructions, since almost everything we can lay hold of, at all compatible with the dimensions of the Aquarium, will be likely to thrive;—those who will accompany us in our "Rambles by Rivers," may glean some information on the subject which it is unnecessary to repeat here.
There are many minor details as to the management of Aquaria, for success in which our readers must use their own discretion;—patience, we have already said, will have to be exercised, but above all things avoid overstocking, and never allow the water to become tepid.'
- ↑ "Rustic Adornments." page 24.
- ↑ Swainson's "Habits and Instincts of Animals." page 116.