As hinted, they live shoulder to shoulder, back to back, and otherwise mutually support each other. They need not look about for a single meal, but have merely to allow themselves to be fed by the waves, which yield them a constant supply of fresh and wholesome food. Their sole duty in this respect is limited to the selection of objects suitable to their palate. Their 'at homes' being so frequent, the Mytili can boast of a large circle of acquaintances. The Periwinkle, and his friend Silver Willie, often make a morning call, take pot luck, as it is termed, and then politely retire. Mr. Carcinus Mænas and his poor and dirty relation, Maia Squinado, perchance look in of an evening. Solaster Papposa, or occasionally the lanky-legged Uraster Rubens, and other 'stars' of the marine world, crawl in at unseasonable hours in their usual lazy style, and are generally rewarded by finding the doors (valves) shut against them. This 'cut direct' does not appear to be at all annoying; or if so, the Star-fishes are too cunning to show it, for they quietly saunter away as if they never had the slightest wish to put their feet within their neighbour's dwelling.
There is a 'black sheep,' as Sir Pertinax Mac Sycophant would say, who intrudes himself into Mussel society, and plays sad havoc among its members. This crawling rascal is the wolf of all Musseldom flocks. Young and old alike experience the blighting effects of his villanous propensities. The name of this obnoxious personage is Purpura Lapillus (Common Whelk). What, the reader will ask in surprise, a univalve prey upon a bivalve? Is that possible? It is, unfortunately, too true.
If we take a Mussel in our hand we shall find it perfectly impossible to force its valves asunder, without the aid of a strong knife or other instrument; yet the Common Whelk, fleshy and insignificant creature though it be, will consume the animal within, and make the valves fly open in a brief space of time, by means of its soft tongue. But leaving such general remarks, let us suppose we are standing before a boulder covered with these mussels. Numbers of gaping shells may be at intervals perceived still attached to the rock, but with the interior of each valve so empty and smooth, that we could scarce believe they had ever embraced a living occupant. On taking up one of the valves and closely examining it, do you observe nothing peculiar about it now? 'No.' Take up the other then, and submit it to a similar inspection. Well, what do you see now? 'Nothing,' you still reply, 'unless it be a peculiar little hole about the size of a pin's head, which surely is of no importance.' That little hole was of vital importance to the poor mollusc, for through that aperture the life and substance of the Mytilus was drawn by the voracious Purpura.
But the poor Mussel is exposed to the attacks of other enemies—aquatic birds, as sea-gulls and ducks, eagles, vultures. Even water-rats and monkeys may also be included in the list.
It is amusing to see a gull, by no means a foolish bird, standing patiently before a Limpet, for example. The animal, unsuspicious of the presence of an enemy, raises his canopy with the view of relaxing his overstrained muscles, and is instantly toppled over by the intruding beak of the bird. If unsuccessful in his first attempt, the gull is well aware it would be useless to try a second time at that tide.
But if a Mussel be the object of attack, it is wrenched from its seat, raised to a certain height, and then allowed to drop upon a stone with the view of breaking the shell. In one locality called Mussel Bay, Mr. Barrow says he disturbed some thousands of birds, and found so many thousands of shell-fish scattered over the surface of a heap of shells, that, for aught he knew, would have filled as many thousand waggons.
This habit of the feathered tribe was, by the way, well known to the ancients, and I may be pardoned relieving my pages by a quotation on the subject from the 'Shepherd's Calender' of Spenser, whose exquisite descriptions of natural history are as marvellous as his allegorical poem. The author of the 'Fairy Queen' thus humorously reads a lesson to an ambitious man,—
"He is a shepherd in gree,
But hath been long ypent,
One day he sat upon a hill,
As now thou wouldst mee;
But I am taught by Algrinds ill,
To love the lowe degree.
For sitting so, with barred scalpe,
An eagle soared hye,
That weening his white head was chalke,
A shell-fish down let flye!
She weened the shell-fish to have broke,
But therewith bruised his brayne,
So now astoined with the stroke,
Hee lyes in lingering payne!"
It seems remarkable that the 'illustrious French naturalist,' Reaumur, should have been the first, if not to discover, at least to publish, any description of the manner in which the Mussel spins its silken cable. Yet one hour's experience in a tea-cup or tumbler will exhibit most of the features in this interesting process.
That Reaumur's narrative, although usually copied by most writers of the present day, is not strictly correct, and, moreover, that the foot of the mussel is not 'useless as an instrument of progression' (as generally asserted), may be easily proved to the satisfaction of the student by adopting some such simple experiment as that which I am now about to describe:—