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.
[Illustration: PLATE VII.
1. Actinia clavata.
3. Pennatula phosphorea.
4. A Shell of the Common Whelk, on which are two specimens of Balanus.
5. A group of Ascidians.]
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.
[Illustration: PLATE VIII.
1. Actinia gemmacea.
3. & 4. Actinia mesembrianthemum.
5. Lucernaria auricula.
6. Virgularia mirabilis.]
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.
[Illustration: PLATE IX.
1. Actinia anguicoma.
2. Cucumis hyalinus.
3. Echinus sphæra.
4. Alyconium digitatum.]
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.
[Illustration]
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