Nearly all the other Hydrozoa are marine productions, and comprise among them numerous beautiful forms. Take, for example, the polyp known as Praya diphyes, a double, bell-shaped body, with a long tail, as it were, of feelers, a floating fishing-line; or, another delicate organisation of the same family, Galeolaria aurantiaca, the orange galeolaria. Here are two floating bladders with a connecting chain of polyps; the floats aiding to support, as it were, a whole colony! But the large order Physophoridæ deserves more than a mere passing notice, on account of the graceful forms of delicate tissue and colour which are included under it.
These inhabitants of the sea are essentially swimmers, having mostly true swimming bladders, more or less numerous and of varied form; they always float on the surface. M. de Quatrefages, the distinguished French naturalist, describing one of these organisms, Apolemia contorta, tells the reader “to figure to himself an axis of flexible crystals, sometimes more than a mètre (forty inches) in length, all round which are attached, by means of long peduncles or footstalks equally transparent, some hundreds of bodies, sometimes elongated, sometimes flat, and formed like the bud of a flower. If we add to this garland of pearls of a vivid red colour and infinity of fine filaments, varying in thickness, and giving life and motion to all these parts, we have even now only a very slight and imperfect idea of this marvellous organism.”
The Agalma rubra is thus described by Vogt, a great authority. “I know,” says he, “nothing more graceful than this agalma, as it floats near the surface of the waters, its long, transparent, garland-like lines extended, and their limits distinctly indicated by bundles of a brilliant vermilion red, while the rest of the body is concealed by its very transparency; the entire organism always swims in a slightly oblique position near the surface, but is capable of steering itself in any direction with great rapidity. I have had in my possession some of these garlands more than three feet in length, in which the series of swimming-bladders measured more than four inches, so that in the great vase in which I kept them the column of swimming-bladders touched the bottom, while the aërial vesicle floated on the surface. Immediately after its capture the columns contracted themselves to such a point that they were scarcely perceptible, but when left to repose in a spacious vase, all its shrunken appendages deployed themselves round the vase in the most graceful manner imaginable, the column of swimming-bladders removing, immovable in their vertical position, the float at the surface, while the different appendages soon began to play. The polyps, planted at intervals along the common trunk, of rose-colour, began to agitate themselves in all directions, taking a thousand odd forms; ... [pg 119]but what most excited my curiosity was the continuous action of the fishing-lines, retiring altogether sometimes with the utmost precipitation. All who have witnessed these living colonies withdraw themselves reluctantly from the strange spectacle, where each polyp seems to play the part of the fisherman who throws his line, furnished with baited hooks, withdrawing it when he feels a nibble, and throwing again when he discovers his disappointment.” The agalma is described as well armed; its tendrils have enormous stinging powers.
AGALMA RUBRA (THREE-FIFTHS NATURAL SIZE).
One family of the Physophoridæ includes the interesting creature known as the “Portuguese man-of-war,” from a slight resemblance to a small vessel with a sail up; it is also known among sailors as the sea-bladder. The bladder is eleven or twelve inches long, and from one to three broad. Its appearance is glassy and transparent, and of a purply tint. Above the bladder is a crest, limpid and pure as crystal, and veined in purple or violet; it is the crest which the sailors believe fulfils the office of a sail. “This bladder-like form, with its aërial crest, is only a hydrostatic apparatus, whose office is to lighten the animal and modify its specific gravity.” From the bottom of the bladder a crowded mass of organs, most of which take the form of very slender, highly contractile, movable threads, depend; they are often several feet, and occasionally several yards, long. Their stinging powers are great; these elegant creatures are terrible antagonists. One French writer says that, “One day, when sailing at sea in a small boat, I perceived one of these little galleys, and was curious to see the form of the animal; but I had scarcely seized it when all its fibres seemed to clasp my hand, covering it as with bird-lime, and scarcely had I felt it in all its freshness (for it is very cold to the touch), when it seemed as if I had plunged my arm up to the shoulder in a cauldron of boiling water. This was accompanied with a pain so strange, that it was only with a violent effort I could restrain myself from crying aloud.” Another traveller,[32] while bathing and swimming in the surf of the Antilles, was attacked by one. “I promptly detached it,” says he, “but many of its filaments remained glued to my skin, and the pain I immediately experienced was so intense that I nearly fainted.” In this case no very serious damage resulted, but during the voyage of the Princess Louise round the world a seaman was nearly killed by one. Frédol, the historian of the expedition, says that one of the officers noticed a magnificent Physalia, which was floating near the ship. “A young sailor leaped naked into the sea to seize the animal. Swimming towards it, he seized it; the creature surrounded the person of its assailant with its numerous thread-like filaments, which were nearly a yard in length; the young man, overwhelmed by a feeling of burning pain, cried out for assistance. He had scarcely strength to reach the vessel and get aboard again before the pain and inflammation were so violent that brain fever declared itself, and great fears were entertained for his life.” It is a disputed point whether the Physalia is poisonous or not when eaten. It was a commonly-received idea in the Antilles that they are, and that the negroes sometimes made use of them, after being dried and powdered, to poison both men and animals. The fishermen there believe that fish which have eaten parts of the Physalia become unfit for human food. A French physician, M. Ricord-Madiana, settled in Guadaloupe, made many experiments to attempt the settlement of the question. He found that ants and flies partook of them with [pg 120]impunity; a dog, a puppy, and a fowl, swallowed parts of them nearly with impunity, the first named only seeming to have severely felt the sting in his mouth, but recovering perfectly soon after. The ardent experimentalist next ate, and caused his servant to eat, the chicken which had fed on Physalia, and no inconvenience followed; subsequently he ate twenty-five grains of the dried and powdered animal in a little bouillon, and he was unharmed. Yet there [pg 121]is some evidence on the other side which would indicate that on occasions, at least, it is poisonous.
The habits of the Physalia are only known in part, though they have been studied by many scientists. Among the many denizens of the ocean, “none,” says Gosse,[33] “take a stronger hold on the fancy of the beholder; certainly none is more familiar than the little thing he daily marks floating in the sun-lit waves, as the ship glides swiftly by, which the sailor tells him is the ‘Portuguese man-of-war.’ Perhaps a dead calm has settled over the sea, and he leans over the bulwarks of the ship, scrutinising this ocean-rover at leisure, as it hastily rises and falls on the long, sluggish heavings of the glassy surface. Then he sees that the comparison of the stranger to a ship is a felicitous one, for at a little distance it might well be mistaken for a child’s mimic boat, shining in all the gaudy painting in which it left the toy-shop.
“Not unfrequently one of these tiny vessels comes so close alongside that by means of the ship’s bucket, with the assistance of a smart fellow who has jumped into the ‘chains’ with a boat-hook, it is captured and brought on deck for examination. A dozen voices are, however, lifted, warning you by no means to touch it, for well the experienced sailor knows its terrible powers of defence. It does not now appear so like a ship as when it was at a distance. It is an oblong bladder of tough membrane, varying considerably in shape, for no two agree in this respect; varying also in size, from less than an inch to the size of a man’s hat. Once, on a voyage to Mobile, when rounding the Florida reef, I was nearly a whole day passing through a fleet of these little Portuguese men-of-war, which studded the smooth sea as far as the eye could reach, and must have extended for many miles.” It is often to be seen on the coasts of Devon and Cornwall, brought thither by the Gulf Stream.
PHYSALIA ANTARCTICA.