CHAPTER V.

THE ZOÖPHYTES.

The Aquarium having been furnished with its vegetation, and rendered as picturesque as possible by the well-arranged juxtaposition of felicitously-contrasting forms and colours, the water must be allowed to settle for some days, until it is as clear as pale-green crystal, before the animals are introduced to their new home. When the Alpine scenery of the submarine landscape appears perfectly settled, and all its colours and forms are seen with beautiful distinctness through the clarified waters, then the still life is ready to be associated with the more active organizations of animated creatures. Before speaking of Molluscs, or Crustacea, or of Fish, suitable to the Aquarium, let us first devote all our attention to our _Zoöphytes_, those singular creatures whose strange instincts and anomalous forms have been mainly instrumental in attracting the attention of many classes of the public to that curious interest in Aquaria, which is fast spreading into a mania, threatening to absorb all others in its vortex, like _Infusoriæ_ drawn within the fatal tentacles of the _Actinia_.

First, of the _Actiniæ_, or Sea-Anemonies. These flower-formed animals were once thought to form a curious and astonishing link between the animal and vegetable world; and many curious speculations, based upon that idea, were put forth, among which the links between man and the inferior animals, and between quadrupeds and fishes, were asserted in further illustration of the theory. But the deceptiveness of superficial knowledge, based upon imperfect observations, was never more strikingly exemplified than in the present instance. It was thought that, because these creatures were found attached to rocks, they necessarily drew their nourishment principally through the medium of roots, as all true plants do; more accurate observation, however, has shown that they are not _permanently_ fixed to the rocks, and that they have the power of moving from one place to another, and attaching themselves anew, whenever a sufficiently disturbing cause renders such removal desirable. Again, oysters and mussels remain fixed to rocks without being considered allied to plants on that account; and even some fish have the power of attaching themselves to such and other substances by means of curiously-formed ventral fins, peculiarly fitted for the purpose. The pretty little two-spotted sucker, _Lepidogaster bimaculatus_, possesses this faculty.

But the flower-like form into which the arms, or food-seizers, of the _Actiniæ_ are spread, radiating from a centre like the petals of a flower, was the main reason for supposing a close analogy between these strange creatures and plants—a fancy now utterly abandoned, as it is quite evident that they are furnished with a mouth and stomach, like all true animals, and with a set of arms called tentacles for seizing their prey; and, perhaps, at the same time, through the medium of delicate ciliæ with which the tentacles are connected, with a breathing apparatus, through which a current of water is taken in, and discharged after its oxygen has been abstracted.

The discovery of the true nature of these singular creatures has not, however, changed their flower-like appearance, which to a superficial observer is as deceptive as ever; and few (not professed naturalists), observing these singular _Zoöphytes_ for the first time, would hesitate to pronounce them a kind of sea-plant.

Let us turn, for example, to Plate VIII., and note the appearance of the two varieties of _Actinia dianthus_—the carnation-like _Actinia_, as its name imports—and we shall easily excuse our early naturalists their pretty but erroneous fancies concerning them. This species is more subject than many others to vary in colour, even like the flower after which it is named, being found of every tone between snow-white, orange, pale scarlet, and blood red—while some specimens take duskier tints, from a dull brown to a kind of orange green. But we will describe our illustrations of this genus in regular succession, noting what is most peculiar in the subjects of each Plate.

Plate VI. contains a representation of one of the last-discovered species of _Actiniæ_—one which displays a habit that distinguishes it from all its congeners hitherto described by naturalists, and which has entitled it to be classed as a separate genus, and named _Edwardsia vestita_. The generic name is from that of a well-known naturalist, and the specific name, _vestita_, from its habit of forming for itself a shell, or clothing, into which it has the faculty of retiring at pleasure; or, if an inhabitant of the shallow water, when the tide recedes, and leaves it inconveniently exposed to the air. This species, unless it have the power of quitting its shell, like some Molluscs, is of necessity permanently fixed and confined to the position in which the egg from which it was hatched was placed by the instinct of the parent, or the caprice of the waves. The other objects in Plate VI. will be described in another place.

In Plate VII. we have two remarkable species; the one with drooping tentacles of dull brick-red, being a very curious variety. The species below is _Actinia clavata_, one of the most delicately-beautiful species, which, from its brilliant whiteness, at once attracts the attention.

In Plate VIII. are two varieties, previously described, of _Actinia dianthus_, the plumose or feather-like Anemone. In front, below them, is the representation of one of the most splendid of all the species, having received the specific name _Gemmacea_, from the gem-like appearance produced by the touches of colour—blue, buff, and brown—about the orifice of the mouth or stomach, and about its sharply-pointed tentacles. The stem or body is also variegated with rows of brightly tinted tubercles, and its whole surface is clouded with pale iridescent, or rather nacreous, tones of pink and azure, varied with occasional flashes of orange. All the species are furnished with tubercles of a similar description about the stem or body, but in many they are not so conspicuous, and in others almost imperceptible; yet they no doubt exist in all, as they are not merely ornamental, but essential organs, peculiar to this class of creatures; being reservoirs from which they can shoot forth a thread, furnished with a barbed and poisoned dart, by means of which they are able to attain an enemy, or victim, far beyond the reach of their tentacles. Mr. Gosse very graphically describes the death of a small fish struck by one of these thread-borne poisoned arrows, at some distance from the offended _Actinia_, who launched his dart, as it seemed, for no greater provocation than a slight disturbance of the water rather nearer to his retreat than was agreeable.

The _Actinia gemmacea_, it would appear, is a more voracious creature than most of his congeners, for Dr. Johnston, in his splendid work on the British Zoöphytes, describes one of this species that had managed to swallow a shell of _Pecten maximus_ as large as a common saucer, its own natural diameter not exceeding two inches. It managed, however, to distend its elastic form sufficiently to receive the enormous prey; but the shell divided the stomach into two completely separate departments, the lower one being thus perfectly shut off from its usual supplies. To meet this difficulty, the organic economy of the creature adapted itself in a most extraordinary manner; a new mouth was opened below the division, furnished with two rows of new tentacles, and thus the lower portion regained a means of taking in nourishment, the whole creature forming a singular double monster, that, not contented with its one giant mouth, surrounded with its hundred arms to supply its voracious appetite, had actually succeeded in supplying itself with a second, equally furnished with its formidable feeding apparatus.

In Plate IX. a very beautifully distinct form of this singular race of animals is very carefully delineated—_Actinia anguicoma_—which seems to be shaking loose a mass of serpent-like hair, like another Medusa; from which appearance, its specific name _anguicoma_, signifying snake-haired, has doubtless been given.

The tentacles of the _Actinia mesembrianthemum_ are generally of a beautiful rosy-pink, and the body of a rich warm brown. But of all the species, _A. crassicornis_—represented in the lower part of Plate X.—is perhaps the handsomest, the orifice or mouth being of a delicate straw tone, the tentacles white, variegated with bands of delicate pink, and the body, or stem, a rich orange-brown, thickly sprinkled with tubercles of bright yellow. This fine species sometimes measures five inches across, when the tentacles are fully expanded.

When the _Actiniæ_ are in a state of repose or sleep, the tentacles are entirely drawn in, and the stem or body closes over the orifice, leaving only a slight indent to mark its existence. In this state they might be mistaken for short-stemmed fungi, the pale-bodied species being very much like a half-grown mushroom, if one can imagine it placed close to the ground, without any visible stem.

Most of the species can be easily detached from the rocks to which they are found adhering, but in some cases it is found necessary to cut out the portion to which they cling, by means of a hammer and chisel. But when this is done, and they are placed in the Aquarium, they often willingly leave the stone to which they are attached, which they would not do by gentle persuasion, or any moderate amount of force; and they then take up their station on some suitable portion of the artificial rock-work, just as those do that have been originally detached from their native rocks. Above twenty species of _Actiniæ_ are known to British naturalists.

The _Lucernariæ_ are another class of Zoöphytes, or plant-like creatures, as the term _Zoöphyte_ implies, being formed of the Greek word, _Zoön_ (ξωον), signifying a thing possessed of animal life, and _phyton_ (φυτον) a plant. This general term is applied to all the creatures—some of very distinct character—that belong to this class, which forms a separate division of natural science, known as Zoöphytology.

The species of _Lucernaria_, which has received the specific denomination of _auricula_, from its slight resemblance in form to the flower of that name, is delineated in Plate VIII., attached to a slender branch of sea-weed, just above the two large Sea-Anemonies. This species of _Lucernaria_ is generally of a light pinkish colour, and is, in general form, perhaps more like a Convolvulus than an Auricula. Two species have been most beautifully delineated in all their details by Mrs. Johnston, in her husband’s magnificent work on British Zoöphytes. These drawings are, in fact, so charmingly and, at the same time, accurately executed, that it would seem that the pencil ought to be guided by delicate female fingers when portraying these minutely-intricate and unusual forms of animal life. The exquisite drawings by Mrs. J. E. Gray, in her work on the curious molluscous animals, whose habitations alone, the beautiful sea-shells of our cabinets, were, till recently, all that was known of them, afford further evidence, if it were needed, of the aptitude of the more finely-strung female capacity for this department of scientific portraiture. The name of Mrs. Griffiths is also honourably associated with the study of natural science, especially that connected with our marine _Algæ_—a beautiful division of sea-weeds—having received its name Griffithsia, in honour of the esteemed services of that accomplished lady.

The _Lucernaria campanulata_, which is of a somewhat more bell-shaped form than the preceding, is of an uniform liver colour; and in the hollow of the flower-like cup the “mouth” projects, in a square form in the centre. There are three known species of British _Lucernariæ_, which would all form highly curious objects in the Aquarium; but they are excessively delicate and fragile creatures, hanging suspended from the object to which they are attached, when taken out of the water, like a mere lump of jelly, and would doubtless be very difficult of transport, and probably not capable of retaining life in a state of confinement, except for a short time.

The “compound Zoöphytes,” or, more properly, _Polyps_, as being, as it were, many creatures in one, are still more curious than the two classes just described. A common example of this class is the _Alyconium digitatum_, looking like a mass of short fingers, when the final florets are closed, as its specific name imports, being sometimes called, by the fishermen of our northern coasts, Dead-men’s-toes. Each finger-like cell contains a separate creature, whose tentacles, when expanded, form the floret, after the manner of those of the Sea-Anemonies, but yet each separate creature is vitally attached to a central polypidom, or spine, which binds the whole group into one existence.

Of this class are the curious _Pennatulidæ_, one of which is commonly known as the Sea-Pen. The three species of this class of _Polyps_ known to inhabit the British seas, are so distinct from each other that they form at the same time three distinct genera. The most beautiful of the three is the _Pennatula phosphorea_, the Sea-Pen, which is not uncommon on some parts of our northern coasts. It is represented in Plate VII. The purple branches, or pinnæ, of the upper portion, form the feathered part of the quill pen to which it is likened; the bare portion of the polypidom below having certainly some resemblance to the quill. This curious zoöphytic form is often seen in an erect position, planted, as it were, in the mud like a miniature purple Pine, though it is capable of motion through the water from place to place, by some action of its organs which has not been accurately detected. It is one of the handsomest of our British Zoöphytes. The polypidom, or trunk, is three or four inches long, fleshy, and of a purplish red. It is naked at the lower end, and feathered above with long, closely-set pinnæ, along the margins of which the polyp-cells are placed. The pinnæ are curved backward, and capable of either separate or united motion. They are supposed by some to be capable of the action of regular oars; but this is very doubtful, though their bearing on the polypidom, which is strengthened by an internal column of calcareous or bony matter, would give them considerable power for that purpose. The creature’s specific name, _phosphorea_, must not lead to the supposition that it always emits a phosphorescent light, for it is only when irritated that this is produced. If plunged into fresh-water, it scatters a shower of phosphoric sparks in all directions, which forms a magnificent and curious spectacle, far more brilliant, no doubt, than the fabled hues of the dying dolphin.

The _Virgularia mirabilis_ is another of this class of creatures, almost as elegant as the Sea-Pen, but more slender, and in the form of a branching rod, as its name imports. (See Plate VIII.)

The Sponges form a curious class of Zoöphytes, which have perhaps a much closer affinity to plants than any other. They are occasionally very sportive, and curious in their forms; and Dr. Johnston enumerates fifty-six species belonging to our coasts; they are, however, unsuited to the Aquarium in the present state of our knowledge; and when portions of rock are collected on the shore, for the tank, care should be taken to clear off any Sponge formations that are perceived, as their certain and rapid decay would be liable to injure the condition of the whole colony of the Aquarium.