Among the most beautiful and fragile of all animals are the singular forms which we call jellyfishes (Fig. 19). They are so delicate that we can not lift them, and in many instances they have ninety-five per cent of water in their composition. They would almost seem to be purely ornamental did we not know that they fill an important niche in the hall of nature, constituting almost the sole food of many whales.

The jellyfishes are found in all waters, salt and even fresh. They may be seen floating near or at the surface, often in vast numbers. Sometimes they are found deep in the heart of the upper part of the ocean, often in such quantities that the water appears to be filled with their graceful shapes.

In the Santa Catalina Channel a beautiful lavender-hued form is common, the water being alive with them at times, and I have seen specimens with tentacles streaming behind them an estimated length of twenty feet, the entire animal appearing like a huge comet in the blue sky of the ocean. Mrs. Agassiz describes a jellyfish called Cyanea which was six feet across its disk and which had tentacles over one hundred feet in length. Specimens have been seen in East Indian waters which were much larger, having an estimated weight of several tons. An English naturalist describes one which stranded in India and gave out so vivid a light at night that the natives were afraid to approach it; yet large as was this monster, a few hours in the sun caused it to disappear or literally evaporate, water forming so large a part of its make-up.

In appearance the jellies resemble umbrellas, dinner plates, or inverted bowls, from which depend streamers or tentacles of various kinds and shapes, often richly colored, especially the very minute forms. The mouth is in the center, the eyes are around the edge of the disk, while the huge tentacles, which can be lifted or lowered as fancy dictates, are so many fishing lines by which this jelly finds its food. I have often watched them floating near the surface, the delicate vermilion-tinted tentacles floating gracefully about, and serving as so many tempting baits. Should a sardine or other small fish venture to attack this tempting lure, we can almost imagine it struck by an electric shock, as it rolls over dead. The secret is very easily discovered. Lift the tentacles with the hand and a burning sensation will be experienced, in some cases very painful. The tentacles of the jellyfish are armed with stings.

The weapons are known as lassos (Fig. 20). Under the microscope the tentacles appear to be filled with little cells or oblong objects, which when examined are found to be capsules (C) resembling long glasslike bodies in which is coiled a thread. This latter is a miniature javelin, and when the tentacle of a jellyfish is seized by a fish or an enemy, tens of thousands of these cells literally explode (D) and the javelin springs out like a Jack-in-the-box (A) and penetrates the intruder. With many jellyfishes the effect of this bombardment is a stinging sensation. It paralyzes small fishes which, when benumbed, are lifted up by the tentacles and eaten.

The jellies develop in various ways. In Figure 21 we see a common and very beautiful form resting on the rocks. Near by are various little plantlike creatures, the young jellies, which undergo a remarkable series of changes in their growth from the egg to the adult form. Minute eggs are deposited in the autumn, which drop into the crevices of the rocks and soon change to pear-shaped objects which attach themselves to the bottom. Each little jelly pear (Fig. 22) divides after a while until it looks like a pile of platters one upon the other. The upper one dies, and the rest break away, each becoming a separate jellyfish, which ultimately grows to be a giant.

The story of the growth and development of these little jellies is one of the most marvelous pages in the history of nature. In some forms the father and son are entirely different, and it is only the father and grandson that resemble each other. Not only this, the father is a seeming plant, while the son is a free-swimming jellyfish of great beauty. The seeming plant is in reality a hydroid community. The buds are immature jellyfishes which finally break away and assume the typical jellylike form, free swimmers bearing not the slightest resemblance to the parent. This jelly deposits eggs which attach themselves to the bottom and become not jellies but the shrublike form. Hence it is the parent and its grandchildren that bear a close resemblance to one another.

No conception of the beauties of the jellyfish can be formed from pictures, or from the stranded "sunfishes" found along the shore at low tide. In the water they move along or swim by the slow pumping or rising and falling of the umbrella or disk, and are of all the colors of the rainbow. Some, like the dark, lavender-splashed specimens, can be seen from a long distance, while others are almost invisible, in fact, are like glass or crystal, and interpose no obstacle to other forms beyond. The ocean is filled with them; their chaste shapes presenting one of the most beautiful spectacles to be observed in the ocean as they drift about. Some are merely great disks towing behind them enormous masses of pink fluted jelly, as in Figure 23; others are simple flowerlike forms (Fig. 24).

If these graceful forms are beautiful during the day, what shall we say of them at night, when they blaze and glow with marvelous phosphorescent lights of yellow, green, and gold. Gazing into the ocean these great jellies appear like comets moving through the clear atmosphere of the sea. The Cyanea is pale blue. One jelly, called Melicerta, emits a pale golden radiance, and Rhizostoma (Fig. 25) gives out a fixed steely blue light. It would be difficult to find one out of all this marvelous procession of living gems that does not emit a light more or less peculiarly its own.

But the most magnificent display is seen at Point Firmin Light during a storm. Here stands a lofty rock pillar which has breasted the sea for ages. At low tide, when a storm sea strikes the ledge, the spray rises to an altitude of three hundred feet, and spreading as it rises, fairly fills the air with a gigantic mass of silvery light, that on a dark night presents an appalling spectacle as it drops, changing its shape continually. On such nights the line of breakers changes into silvery flame, while the roar resembles a cannonade, fairly shaking the earth. In the breakers the jelly light givers are breaking up and adding fuel to the seeming flame. Some, as Pelagia, are luminous over their entire surface; in others, the light is confined to certain parts, which are either fixed or flashing lights. How vivid this light is may be imagined when it is said that a single jellyfish, Aurelia, when squeezed into a glass of milk, has produced a light by which a letter was read.

This peculiar phosphorescence is not their only interesting feature. Nearly all the jellies afford protection to fishes, crabs, and various small animals. As I drifted over the waters of the Gulf of Mexico almost every large jelly that I examined had one or more little fishes of the mackerel family up among its lobes or tentacles. As they always resembled the tentacles in tint or color, a delicate pink, they found protection amid the death-dealing darts. The most remarkable example of this strange companionship of dangerous jellies and delicate fishes is found in the Physalia, or Portuguese man-of-war (Fig. 26), one of the most beautiful of all the animals that make up the group to which the jellyfishes belong. Physalia is a bubble tinted with purple hues, four or five inches long—a fairy ship of pearly tints. On its upper portion is a sail which can be raised and lowered, while from the lower part depends a mass of beautiful blue or purple tentacles which sometimes are nearly one hundred feet in length. During the summer of 1902 I found them on the outer islands of the Texan coast in great numbers, stranded on the sands, while scores of others sailed on through the pass into the quiet waters of Aransas Bay. Among the islands of the Tortugas group I often saw them dotting the calm waters, the sunlight on their delicate tints presenting beautiful combinations of colors.

It may appear strange that one of the most resplendent of animals should be the most dangerous, yet such is the case. The attractive tentacles which drag behind the Physalia are deadly to almost every fish. I have found a hawkbill turtle weighing twenty pounds caught and benumbed by one; and fishes which touch the seeming worms roll over dead, as though stunned by an electric shock. In swimming around one of the keys of the reef I unwittingly passed over the train of one, and if I had been alone, I doubt if I could have reached the shore, so terrible was the burning pain. A year afterward my flesh had the appearance of having been tattooed in fanciful designs. Yet despite the deadly nature of this maze of traps and lures, a little fish lives up among them, and what is more remarkable, is the exact color of the tentacles, a rich blue. So exact is this resemblance that it is very difficult to see the little attendants, but if you lift the dainty man-of-war by its sail, they rush about greatly alarmed by their exposed condition. I have been told that the Physalia eats these attendant courtiers, but in hundreds of specimens which I examined I never saw the little fish in the toils. They swam about among the death-dealing tentacles with the greatest freedom. The secret of the poison lies in the lasso cells of the tentacles, as in the case of the jellyfish, but in this instance they are much more poisonous. Along the southern beaches, where the Physalia is common, their stranded hulks form after storms a windrow of mimic balloons which explode like torpedoes beneath the feet, as one strolls along the sands.

No branch of the animal kingdom contains more beautiful and radiant forms than that which includes the Portuguese man-of-war. They are the fairy crafts of the sea, graceful, seemingly formed of water in some instances, and nearly all so delicate that they usually drop to pieces when captured. I have kept all for a brief time in confinement, but few survived more than a few hours.

In a tank at Santa Catalina Island I had at one time, besides a Portuguese man-of-war, the delicate Velella, a raft of sheeny silver which floated on the surface, having a silvery sail (Fig. 27), beneath which hung short tentacles of a brilliant hue. More beautiful than these were the "swimming bells"—strings of beautiful pink and crystal bells attached to a central cord (Fig. 28). One of these, Praya, three or four feet long, was a veritable string of little pumps, each of which pumped water very rapidly, urging the entire animal along. Each little cup seemed carved in glass and colored by some artist, so perfect were the tints, so delicate was the design. Many of these forms could be seen in the ocean only by fitful glances, so delicate were they. Most beautiful of all these prisoners in the tank was one called Physophora, or by the Italian fishermen, Boguetti. It had a central stem like the glass of a thermometer, the bulb being uppermost and filled with a gas that was almost exact in its resemblance to mercury. When the bulb was full the animal floated at the surface. I have watched the animal force the gas down by repeated restrictions of the tube until it could descend beneath the surface with ease. On the sides of the central pillar were numbers of beautifully tinted pumps, the locomotive organs. Underneath was a mass of lacelike tentacles, richly tinted, purple and vermilion, so Physophora was one of the most gorgeous objects to be imagined. A unique feature of this animal was its rapid movements. When it so desired it dashed around the tank with great velocity, in strange contrast to the labored movements of other jellylike forms, or the utter and complete helplessness of Physalia, Velella, or Porpita. These latter were ships at the mercy of every breeze, the Physalia alone being able to anchor itself on a lea shore, but always beaten in by the heavy surf.