Sea anemone

“ On searching these rock pools we should find many curious animals. None would interest us more than the sea-anemone, though when we find it hiding in some dark corner, with its tentacles all drawn in, and looking like a soft brown lump, it may not promise much beauty.
The sea-anemone adheres firmly to the rocks, so we will not pull it off. If we watch long enough we shall see it begin to rise in the middle, and from the summit will creep out, very slowly and softly, beautiful tentacles like a wreath around the top. ”

“ Nothing can be more unprepossessing than a sea-anemone when contracted. A mere lump of brown or whitish jelly, it lies like a lifeless thing on the rock to which it clings, and it is difficult to believe that it has an elaborate and exceedingly delicate internal organization, or will ever expand into such grace and beauty as really to deserve the name of the flower after which it has been called. ”

“ A sea-anemone, like a coral-polyp, has a mouth and a stomach. But unlike the coral-polyp, it has the mouth and stomach for its own use, not merely in trust for the benefit of the whole community.
When the pretty flower-like creature wishes to open itself out, it takes in a quantity of salt water. When it wishes to shut itself up, it spurts the water out, drawing its tentacles close. ”

“ Every animated thing that comes within reach of the tentacles of the anemone is mercilessly seized and devoured. Even small mollusks and Crustacea are unable to resist the power of the grasping threads, and crabs are often conquered and swallowed by this voracious living flower. For this reason sea-anemones are dangerous inhabitants of an aquarium stocked with creatures having the power of locomotion, and are best placed in a tank with other zoophytes like themselves. ”

“ In many respects Sea Anemones resemble the Hydra, one of the pond dwellers, they are rather more highly developed, however. Any Sea Anemone will serve our purpose because we are about to examine the little darts with which its tentacles, and even its body, are armed. If we find several different kinds of Anemone, we must take the most transparent we can find and also a small specimen ”

“ Sometimes an anemone will detach itself from the rock, and drag itself along, but very slowly, by means of its tentacles, sometimes inverting its body and walking on its head, as it were, and though one may never have the opportunity of witnessing this manœuvre on the shore, we have found it far from an uncommon occurrence in the aquarium.
The natural food of anemones consists of small crustaceans, such as shrimps, and crabs, molluscs, small fishes, and in fact almost every kind of animal diet, and there need never be any difficulty in finding suitable viands for species kept in captivity. ”

“ The water is then squeezed up into the tube-like tentacles, which of course expand. When it wants to close them it relaxes the pressure, and the water flows out of the tubes again and back into the water-jacket, so that they all come folding in.
The lower part of an anemone’s body is called the “foot,” and is really a big and strong sucker, by means of which the animal clings so firmly to the surface of a rock or a stone that it almost seems to be growing out of it. But these creatures do not spend the whole of their lives [123] without moving, as oysters and barnacles do. ”

“ The crab benefits, because no fish will ever touch him so long as an anemone is attached to his whelk-shell. There are plenty of fishes which would be quite ready to gobble him up, whelk-shell and all, if it were not for this creature. But fishes know quite [80] well that sea anemones can sting, and therefore never think of devouring them, no matter how hungry they may be; so that so long as an anemone is guarding the whelk-shell in which he lives, the hermit knows that he is perfectly safe. And the anemone benefits, because it gets a share of the crab’s meals. ”

“ The purple sea anemone is very common on the southern shores of England, and one species, found on the shores of the Mediterranean, is said to be esteemed a great delicacy by the Italians. At night, or when alarmed, the animal draws in its arms, shuts the door, and seems but a rounded lump of flesh, a huge oyster without a shell. ”

“ Sea-anemones have no proper nervous system. The sense of touch is distributed throughout the whole animal. It will, therefore, appear as a remarkable statement that some kinds have quite definitely-formed eyes. These are seen in some tropical species just outside of the tentacles, and according to Dana each of these eyes has a crystalline lens and an optic nerve!
Sea-anemones readily reproduce lost parts. If one is quickly torn from a rock, parts of the foot remain attached to the rock, and in many cases each portion thus left will become a perfect sea-anemone! ”

“ The body of the Sea-Anemone is soft, while that of the Coral is hard. It is well known that all animals and plants have the power of appropriating to themselves and assimilating the materials they need, each selecting from the surrounding elements whatever contributes to its well-being. The plant takes carbon, the animal takes oxygen, each rejecting what the other requires. We ourselves build our bones with the lime that we find unconsciously in the world around us ”

“ Considerable difficulty will sometimes be found in the attempts to preserve a soft-bodied animal in its natural attitude. Thus, when a sea anemone is removed from its native element, it generally withdraws its tentacles, and, contracting the upper part of its cylindrical body, entirely conceals these appendages, together with the mouth they surround; and a mollusc similarly treated will generally pull itself together within its shell, leaving little or no trace of the living body inhabiting the lifeless case. ”

“ Sometimes the Anemone uses the tentacles around the disk to help feed itself, and it also uses the mouth, lips and disk for the same purpose. When the Anemone is at rest it expands its disk and draws in the sea water, and when it is disturbed it contracts, and throws out the water from its mouth. The Anemones are very sensitive to touch, and will shrink up like a sensitive plant. ”

“ Sea-anemones increase by budding as well as by eggs. At the lower edge of the body little round knobs are sometimes formed, which separate from the parent and grow into perfect animals. If the tentacles or other parts of the body are removed, new tentacles soon grow in their places. If an individual is torn in pieces, each fragment has the power of forming for itself a mouth and throwing out tentacles, and becoming a new sea-anemone, perfect in all its parts. ”

“ Valuable reserves prepared by farseeing nature for that time when man will have exhausted his mines on the continents.
In the midst of this hopelessly tangled fabric of weeds and fucus plants, I noted some delightful pink-colored, star-shaped alcyon coral, sea anemone trailing the long tresses of their tentacles, some green, red, and blue jellyfish, and especially those big rhizostome jellyfish that Cuvier described, whose bluish parasols are trimmed with violet festoons. ”

“ But the ordinary jelly fish is free, and borne on the surface of the sea.
The Anthozoa (flower animals) are small, but not microscopic [387] animals, having a double cavity, the inner of which is the digestive sac. The best known of the class is the Actinia (rayed) , or sea anemone, so called from its resemblance to a plant or flower of that name. The body is somewhat like a flower in shape. The disc has a central orifice, very contractile, and surrounded with tubular tentacles of various forms, which it elongates, contracts, and moves in different directions. ”

“ The instinct to cover itself with Actiniæ is so strong within it that it loads itself with as many of these friends as it can procure, sometimes with more than there is room for on the shell. The sea-anemone on its part calmly submits to the crab's manipulations—a fact very surprising to any one who is aware of the anemone's ordinarily extreme sensitiveness to contact, and knows how it immediately draws itself together on any attempt to detach it from the ground, and will often let itself be torn in pieces rather than give way. ”

“ When covered with sea-water the ugly blobs of jelly open out like beautiful flowers. In some places along our coast the floor of the sea is like a flower garden, gay with thousands of coloured Anemones.
Those little "petals" are really tentacles, used for catching and holding food. We will use a shorter word and call them feelers. They are set in circles round the top of the Anemone, and there are many of them. The Daisy Anemone, for instance, has over seven hundred feelers. Each feeler can be moved from side to side, and can also be tucked away, out of sight and out of danger ”

“ The Sea Anemone, which has already provided us with objects for our microscope, has many near relatives which we must make a point of examining, while we have the opportunity. Many of these creatures, or rather their colonies, for they do not live singly, are to the naked eye, strangely like seaweeds. ”

“ The sea-anemone, which otherwise cannot move, is carried from place to place by the crab and so may get a larger supply of food, while the crab is protected from its enemies, the predaceous fishes, by the stinging threads of the sea-anemone, and also perhaps by the concealment of the shell its presence affords. ”

“ The facts recall the familiar case of the hermit-crab, which protects its soft tail by tucking it into the empty shell of a periwinkle or a whelk or some other sea-snail, and that case leads on to the elaboration known as commensalism, where the hermit-crab fixes sea-anemones on the back of its borrowed house. The advantage here is beyond that of masking, for the sea-anemone can sting, which is a useful quality in a partner. That this second advantage may become the main one is evident in several cases where the sea-anemone is borne, just like a weapon, on each of the crustacean's great claws. ”

“ The fish barely touched the anemone, then seemed incapable of moving farther, and after a few struggles became paralyzed. These arrow-points possess the power of motion for several hours after being detached from the animal. Lasso cells can be replaced when lost, and in a very short time. On a square foot there are millions of cells. It is a curious fact that all well-defended animals —I speak with, particular reference to the lower marine animals—are usually brilliantly colored. This can be seen in the case of sea-anemones, tropical shells, and crabs. ”

“ In most cases, however, the facts seem to be that an individual of a definite species of Crab and an individual of a definite species of Sea-Anemone have both at once taken possession of the same mollusc-shell, which they continue to inhabit for their mutual advantage,—the Crab acting as locomotive to the Sea-Anemone, and the Sea-Anemone in return acting as a defence and warning-post, and possibly also as a decoy, for the benefit of the Crab. ”

“ At the sea-side, if one lovely anemone should sicken and fade, it can be removed at once, thrown back into its native element to have a chance of recovery, and its place easily supplied. Queer little fishes which lurk under stones will often live for a long time in a pan of water ”

“ The next glance showed them to be living organisms.
"Sea-anemones!" breathed Edith softly. "I never saw anything so beautiful."
The anemones were pulpy brown bodies varying in size from a pea to a tomato. From their anchorage on the rock they stretched waving tentacles of soft iridescent hues, transforming the little pool into a marine fairyland. Between the anemones a bright yellow lichen-like growth almost covered the warm red granite, and tiny yellow, rose, and black and white striped snails were set like jewels on this background. ”

“ The toxological properties of the Actinia have been attributed to certain special cells full of liquid; but M. Hollard believes that these effects are neither constant enough nor sufficiently general to constitute the chief function of these organs, which are found in all the species and over their whole surface, external and internal. Though quite incapable of discerning their prey at a distance, the sea anemone seizes it with avidity when it comes to offer itself up a victim. ”

“ Fig. 68—A, The Crab Melia tessellata clinging to a Branch of Coral, and carrying in Each Claw a Living Sea-anemone; B, One of the Claws further enlarged to show the Way in which the Anemone is held. (After Borradaile.)
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One of the strangest habits is that of certain little tropical Crabs, of which Melia tessellata (Fig. 68) is the best known, which carry in each claw a living Sea-anemone and use it as a weapon. The claws or chelipeds are in this case of small size, so that they would be of little use by themselves for attack or [216] defence ”

“ If any of the young polypi be mutilated while growing upon the body of the parent, the parts cut off will immediately grow again; and even if the polypus be dispossessed of its extremities, it will produce young ones before it has attained head or tail. The sea-anemone is very beautiful when alive. It is of a most lovely purple, and throws out its numerous feelers like radii from the centre; these feelers it can contract or expand at pleasure. ”

“ It is a very pretty and hardy object in the aquarium. There are many varieties, some of which are very delicate, as the Actinia anguicoma, or Snaky-locked Anemone, and the pink and brown Actinia bellis, which so resembles a daisy. Others, as the Actinia parasitica, are obtainable only by deep-sea dredging; "and, as its name implies, it usually inhabits the shell of some defunct mollusk. And more curious still, in the same shell we usually find a pretty crab, who acts as porter to the anemone. ”