2. Gigartina acicularis.
3. Ceramium strictum.
4. Taonia atomaria.
5. Plocamium coccineum.
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.