THE OYSTER,
Which may be considered as the King of Bivalves; his palace, to be sure, is somewhat rough and rugged outside, but within, its walls are smooth and polished, lustrous and iridescent, and altogether beautiful; of a nacrous or pearly appearance, now flushing into a rose tint, now fading into pure white, and adorned sometimes with goodly pearls of price; truly this monarch of the Conchifers has a habitation worthy of a prince, wherein he lives in right royal state. Our readers may smile perhaps at the idea of the solitary Oyster doing this, down there on his mud bank or rocky anchorage ground, shut up in his dirty-looking shells, and holding, as it seems, commune with no one, not even his fellow mollusks; how can he be said to live in royal state, or indeed any state at all, except in a most weary, stale, flat, and unprofitable one? And this only shews how erroneously those often judge who do so hastily, and from first appearances.
If we take a peep through a microscope, under the direction of a naturalist named Rymer Jones, we shall see that “the shell of an Oyster is a world occupied by an innumerable quantity of animals, compared to which the Oyster itself is a colossus. The liquid enclosed between the shell of the Oyster contains a multitude of embryos, covered with transparent scales, which swim with ease; a hundred and twenty of these embryos, placed side by side, would make an inch in breadth. This liquid contains besides, a great variety of animalculæ, five hundred times less in size, which give out a phosphoric light. Yet these are not the only inhabitants of this dwelling—there are also three distinct species of worms.”
Let us see if there are any hard names here that want explaining before we go any further. The first we stumble upon is Colossus, which comes from the Latin, and means a great image or statue, like that which ancient historians tell us once bestrode the entrance to the harbour of Rhodes. Embryo comes from the Greek, and means something small and unfinished, that is to expand or grow into a more perfect form, as the seed into a plant. Animalculæ, are minute or very small animals, such as cannot be distinguished without the help of a microscope, hence they are sometimes called microscopic animals; this word comes from the Latin animalis, which means having life. Phosphoric signifies luminous, or giving out light. The Greek name of the morning star is Phospha. In Latin, Phosphorus is a term applied to a substance which chemists extract from bones and other animal matter, and which, when exposed to air, burns with a pale blue light, like that emitted by the glow-worm. Many of the oceanic or sea animalculæ are exceedingly phosphorescent, so that by night, the waves appear like billows of flame. Of this luminosity of the ocean, as it is termed, we shall have to speak on another occasion. We will now return to the Oyster, who, it will be seen, is by no means so solitary in his bivalve palace as might be supposed. He has his torch-bearers, and other attendants, quite a host of them, no doubt magnificently dressed, if we could but see them to advantage, and well instructed in the several duties which they have to perform. Oh yes, certainly, as the Irish poet has said,
“Of all the Conchiferous shell-fish,
The Oyster is surely the King;”
Shall we continue the quotation? and say
“Arrah Mick, call the people who sell fish,
And tell them a dozen to bring:
For it’s I that intend to demonstrate,
The creature’s phenomena strange,
Its functions to set every one straight,
And exhibit their structure and range.”
Scarcely will our limited space permit us to do this, but a few of the most remarkable particulars about this common Acephalan, we feel called upon to set before our readers.
First, then, it belongs to the class Conchifera; this is a word which we must stop to examine a little; it seems to come from the Latin concha, which means a shell-fish with two shells, in other words a bivalve mollusk. Second, our Oyster belongs to the class Pectinidæ. Now pecten is the Latin for a comb, and this class includes those bivalve shells whose edges are toothed, or, as it is said, pectinated; in the scallop and the cockle shells this peculiarity is more observable than in those of other members of the class, and these form the typical, or so to speak, pattern genus, pecten. Thirdly, the Common Oyster is a Monomyarian Conchifer. Ah! that’s something like a name for the acephaloid monarch! Look at these two words, mono-myarian, di-myarian, you know of course that mony-syllable means one syllable, and dis-syllable means two. You sometimes hear of a person who leads a monotonous life, and you think perhaps of the Oyster shut up in his shell all alone, one by himself; this notion you now know to be a false one; although it is true that he has but one abductor muscle, and therefore belongs to the division of the Pectinidæ family called Monomyaria, while the Pearl Oyster has two, and therefore belongs to that termed Dimyaria. If, as they say, there is reason in the roasting of eggs, surely there must be in the names given to the classes and divisions of shells. We hope to have succeeded in making the why and the wherefore in this case somewhat plain;—one—two—and away we go out of this maze of hard names. But what about the abductor muscle, above spoken of? well, this must be explained; abduce, coming from the Latin abduco, means to separate, to draw away, hence we have abduction. During the life of an Oyster, the usual and natural state of the shell is that of being kept open for a little distance, to allow the water necessary for its nourishment and respiration to flow in and out; but as a security against danger, it was necessary to furnish the animal with the means of rapidly closing the shell, and retaining the valves in a closed state. These actions being only occasional, yet requiring considerable force, are effected by means of a muscular power, for which purpose one or two, or sometimes more strong muscles are placed between the valves, their fibres passing directly across from the inner surface of one to that of the other, and firmly attached to both, and these are called the abductor muscles, because their office is to draw or pull; how strongly they do this those whose business it is to open Oysters can best tell; if the animal within were not alive, the process would not be a difficult one, as in that case the muscles would be relaxed, and the shell would come open of itself, so that actually people who eat Oysters directly they are opened, swallow them “all alive-O!”
If a pair of the shells from which the delicious morsel has been extracted, be taken in the hand, it may be noticed that one is much thinner, smoother, and flatter than the other; this is the side most exposed to the action of the water; the rougher and rounder side is that which is attached to the rock, or other substance to which the animal forms an attachment, that is usually life-long. The two portions of the shell are joined together by a hinge of curious workmanship, which is formed of the inner layer of the shell, and strengthened by a ligament which is wonderfully elastic; when the shell is drawn together by the abductor muscles, the ligament is at full stretch, and as soon as they relax at all, it contracts, and causes the shell to gape. This process is repeated as often as may be necessary for the safety and sustenance of the animal within, whose mouth is situated at the narrowest part of its habitation, namely, near the joint of the hinge, which connects its upper and under shell. The anatomical structure of the Oyster is more perfect than would be supposed, from its apparently low state of organization; it has a heart, liver, and intestinal canal, and a bag near the mouth, which answers the purpose of a stomach. Its breathing organs are gills, closely resembling those of most other fish; it has little vessels which convey the bile from the stomach to the liver, and may perhaps be subject to bilious attacks, as well as those who swallow this curious piece of organization at a mouthful, without thinking at all of the goodly structure they are demolishing. There is the tiny heart with its series of blood-vessels, just as perfect as in the larger animals. There are the nerves in the shape of minute feelers, which appear to be acutely sensible not only of actual contact with foreign bodies, but also of sounds and movements from without. A very nice sense of feeling appears to reside in what is called the beard, in scientific language bissus; this is a kind of double fringe to the two lobes of the mantle, or sac, as it is called, which envelopes the body of the animal, and floats free from the shell, except just at the part nearer the valve where it is attached.
We have just spoken of the beard of the Oyster, and this reminds us of a conundrum which may serve to amuse our readers, and enliven these dry details a little. Why is an Oyster the most anomalous, that is strange, contradictory, creature in existence? Do you give it up? Well then it is because
“It wears a beard without any chin,
And leaves its bed to be tucked in.”
Again, by this allusion to the “tucking in” of Oysters, a phrase more expressive than polite, we have recalled to memory the saying of a quaint old author, that they are “ungodly, uncharitable, and unprofitable meat; ungodly, because they are eaten without grace; uncharitable, because they leave nothing but shells, and unprofitable because they must swim in wine.” Not, generally, however, are they eaten in this luxurious manner, a little pepper and vinegar is all they commonly get in the way of sauce, and those who swallow them thus accompanied, seem to do so with infinite relish. A very long chapter, if not a whole book, might be written about the historical associations of Oysters, for which our country has been famous, as far back as the time of the first Roman invasion; much, too, might be said about the Oyster beds and fisheries, which give employment to thousands of our industrious population, but all this has so little to do with natural history, that we can find no excuse for dwelling upon it here. It is quite within the range of our subject, however, to state that the “spat” or “spawn” of the Oyster is cast about the beginning of May: at first it resembles a drop of greenish tallow, but by the aid of the microscope it may be seen to consist of a great number of minute particles, each of which is an egg, and will by-and-by become a perfect fish; these increase in size very rapidly, and after floating about for a while, sink to the bottom, and become attached to rock or some other substance, in which position, if not violently detached or removed, they complete their growth, and live out the term of their natural life. Their food is minute animalculæ, and microscopic vegetation, on the nature of which their flavour greatly depends.
They have many enemies besides man; the whelk, and the crab, the sea-star, or “five fingers,” and the large drum-fish, which swallows them almost by the bushel, shells and all; these help to thin the Oyster-beds, and make the dredger’s labours less remunerative than they would otherwise be. Here is a picture of one as he stands in his boat just about to throw his dredge into the sandy bottom, where he knows the delicious testaceans do, or ought to, lie most thickly. The dredge, which is a triangular iron frame with a net over the bottom, will naturally sink, and when the line to which it is attached ceases to run out, the dredger will put his boat in motion, and draw it thus over the Oyster-bed, and then pull it up filled, it may be, with little fat “Miltons,” or large “Colchesters,” or such other kind as the spot is known to yield.
The Latin for Oyster is Ostrea, and that is a name given to a genus of the Pectinidæ family, comprising beside the O. edulis, or Common Oyster, many other species. Edulis means eatable. Home naturalists divide these Ostraceans into two groups, first with simple or undulated, but not plaited valves; second, those which have the borders of their valves distinctly plaited.
To the first group belong the Common Oyster, and between thirty and forty other living species which are found principally in warm and temperate latitudes. In the Polar ocean none have been discovered, and in the hotter climates they are most abundant, being found in large beds or banks near the coast, and often attached to rocks and even to trees which grow by the water, so that the accounts of some old travellers who stated that they saw Oysters growing upon trees, were not so false as many supposed them.
The annexed figure is that of the Cock’s-comb Oyster, Ostrea Crista-Galli, a native of the Indian Seas, and a very remarkable shell, on account of its crooked or deeply indented form; the specific name means cock’s-crest. The Chinese Window Oyster, called Placuna Placenta, which we may, if we like, translate into a pleasant or agreeable cake; the shell, it will be seen, is round like a cake, and its smoothness and regularity of form render it agreeable to look upon; this species too comes from the Indian Seas, where it is taken on sandy bottoms. The American Spiny Oyster, or Spondylus Americanus, brings us into another family, that of the Water Clams, called by naturalists Spondylidæ; with the spines stuck out every way, and no way in particular, it looks like a head of hair greatly in need of the assistance of one of its pectinated relatives. The specific name of this curious shell explains itself; the generic name comes from the Latin Spondylis—a kind of serpent.
Passing over the family Malleidæ, or Hammer Oysters, we come to the Meleagrinidæ, or Pearl Oysters, of which Fig. 1, [Plate VIII], is an example, this is the M. Margaritifera of naturalists, the mollusk in whose shells pearls are chiefly found. Here are two long words; Meleagris is the Latin for a Guinea or Turkey Hen, to the markings of whose plumage naturalists might have imagined the shells of this genus bore some resemblance. There was, says the mythology, a celebrated hero of antiquity named Meleaga, but we can hardly suppose that there is any association between his name and that of a genus of Oysters, of which edible we read the ancients were very fond, and they are said to have had a fancy not only for the mollusk itself, but also for the pearls found in its shell, which at their luxurious banquets they dissolved in wine, to make the draughts richer, or at all events more expensive; and this brings us to the specific name of the Pearl Oyster, Margaritifera, which comes from the Latin Margarita—a pearl; the French use this word slightly altered in the spelling, thus Marguerite for both a daisy, and