Sponge (biology)

“ When we first capture a live sponge from the sea it has a slimy, dirty appearance, and is very heavy. The sponge is found to be filled with a glutinous substance that is the fleshy part of the animal. It is very soft and jelly-like, and after the sponge is dead it is readily squeezed out, by a process which is called "taking the milk out," which leaves simply the skeleton, the only useful part as an article of commerce. ”

“ Under the microscope, these living sponge-units appear in various guises and shapes. Some of them are formless, and, as to shape, ever-altering masses, resembling that familiar animalcule of our pools we know as the Amoeba. These members of the sponge-colony form the bulk of the population. They are embedded in the sponge substance; they wander about through the meshes of the sponge; [pg 208] they seize food and flourish and grow; and they probably also give origin to the "eggs" from which new sponges are in due course produced. ”

“ The living sponge when taken from the water is a slimy, rather repulsive mass which has the general appearance of a piece of raw beef liver perforated with holes and canals. The commercial sponge is merely the skeleton, the supporting framework of the gelatin-like tissues, which is composed of a substance similar in chemical and physical properties to silk, horn and the chitin which forms the shells of insects and crabs. This material is distributed in a fibrous network the pattern of which varies for each species. ”

“ When a fresh sponge is squeezed, this mucilage comes out frothy, by the mixture of the windings of its fibres: it always issues forth with sand, or little parcels of shells crushed by the sea. These fibres, which consist of the twisted doubles of the sponge, form as it were a labyrinth filled with worms, which are easily crushed, and their juice is confused with the mucilage; but having carefully torn the sponges, and their gross fibres, I discovered the living worms, such as I shall mention hereafter.
These species of sponge commonly grow upon sandy bottoms. ”

“ In describing sponge as an animal substance, it may be necessary to explain that the sponge in ordinary use is the flexible skeleton of a living zoophyte, and was originally invested with a gelatinous or slimy matter, which lined all the pores and channels. When alive in the water, currents constantly enter the outer pores, traverse all the internal inosculating canals, and issue from the larger orifices which often project above the surface in perforated papillæ. ”

“ Close to primaeval chaos is the sponge—lowliest of animals. It is an animal without a brain, nervous system, heart, lungs, stomach, muscles or blood. But it has an I Am.
The sponge is in essence an anarchical horde of numberless cells. When the conglomeration is split up as can be done by a technique of squeezing through fine-meshed silk gauze, the cells continue to live as individuals. They crawl about. They take nourishment. ”

“ Grant affirms, though in opposition to M. Cuvier, that the fibrous part of the sponge, which is insoluble in water, and forms a net work through every part of the body, is the skeleton of this zoophyte, serving, as in other animals, to give form to the body, and support to the softer organs.
“Sponge attaches itself sometimes to marine plants, so as to choak up their pores. Small bits of the same species will spread towards each other, and become one piece ”

“ This appears to be due entirely to the absorption of minute particles of inorganic matter by the cells of the parenchyma. If black sponges of the species are kept alive in clean water, they turn pure white in less than a week, apparently because these particles are eliminated. When growing on stones the sponge, as found in India, often conforms exactly with Potts's description: "a filmy grey sponge, branching off here and there ... ”

“ Most of the species start in life as buds from attached animals, which later separate and henceforth lead a free existence, swimming by opening and closing the bell.
SPONGES SPONGES (Porifera) are animals of peculiar structure, which resemble zoophytes in many respects, but possess neither tentacles not thread-cells. Some are simple, but most of them are compound. A simple sponge may be compared to a cup or vase with a wall perforated by numerous small holes, through which currents of sea-water stream into the central cavity, to make their exit by the main opening. ”

“ This sponge is used as a lining to helmets and greaves, for the purpose of deadening the sound of the blow; and this is a very scarce species. Of the close textured sponges such as are particularly hard and rough are nicknamed 'goats'.
Sponges grow spontaneously either attached to a rock or on sea-beaches, and they get their nutriment in slime: a proof of this statement is the fact that when they are first secured they are found to be full of slime. This is characteristic of all living creatures that get their nutriment by close local attachment. ”

“ In Spongilla proliferens, a common Indian species, the buds arise [Pg 45] as thickenings of the strands of cells accompanying the radiating spicule-fibres of the skeleton, which project outwards from the surface of the sponge. The thickenings originate beneath the surface and contain, at the earliest stage at which I have as yet examined them, all the elements of the adult organism (i. e. flesh-spicules, ciliated chambers, efferent and afferent canals, parenchyma-cells of various sorts) except skeleton fibres, gemmules, and a dermal membrane. ”

“ The sponge is definitely not a plant, as some naturalists still believe, but an animal of the lowest order, a polypary inferior even to coral. Its animal nature isn't in doubt, and we can't accept even the views of the ancients, who regarded it as halfway between plant and animal. ”

“ Unless sponges are alchemists and can transmute one element into another, the material of which the spicules are made must ultimately come from the water in which the sponges live, or the rocks or other bodies to or near which they are attached. The amount of water that must pass through a large specimen of such a sponge as Spongilla carteri in order that it may obtain materials for its skeleton must be enormous, for silica is an insoluble substance. ”

“ At this age the sponge is an excellent object for studying in the living condition: being both small and transparent it affords us an opportunity of watching the movements of particles of carmine as they are carried by the current through the chambers.
Potts [209] describes how he has followed the transportal of spicules by dermal cells, the end of each spicule multiplying the motion, swaying like an oscillating rod.
In E. fluviatilis reproduction also occurs during the warmer months in this climate by means of sexual larvae. ”

“ The skeleton is nearly related in structure to silk, and this helped to settle the ancient dispute as to whether sponges were animal or vegetable. Their stationary life gave reason to the belief in their vegetable nature, while they multiply, like plants, by overgrowth and budding. They puzzled scientists for centuries, and one authority regarded them as worms' nests. In reality the sponge is a colony of little animals called polyps which occupy a sort of apartment house together, rearing families just as other animals do. ”

“ The most abundant and possibly the most important organisms that may be considered as benefactors to the Spongillidæ are the green corpuscles that live in the cells of certain species (fig. 2, p. 31) , notably Spongilla lacustris, S. proliferens, and Dosilia plumosa. I have already said that these bodies are in all probability algæ which live free in the water and move actively at one stage of their existence, but some of them are handed on directly from a sponge to its descendants in the cells of the gemmule. ”

“ Not only have sponges so many more useful and interesting parts than the amoeba, but they show, again, how fast you can make differences when you have more than one part to multiply with. Sponges have many different shapes, different colors, and they live in many different kinds of places. One kind of sponge is called the finger sponge, because it has fingers like the human hand. Another is shaped like a banana. Others are almost as round as a ball. ”

“ In one Indian species, however, in which budding is unusually common (viz. Spongilla proliferens) , sexual reproduction takes place very seldom, if ever. It is not known whether the eggs of sponges are fertilized by spermatozoa from the individual that produces the egg or by those of other individuals, but not improbably both methods of fertilization occur.
The egg of a freshwater sponge does not differ materially from that of other animals. When mature it is a relatively large spherical cell containing abundant food-material and situated in some natural cavity of the sponge. ”

“ After I had puzzled in and out of the question, and that our play was ended, my uncle{40} told me that sponges, of which there are now known more than a hundred different species, are found in a multitude of places, on the shores of both the old and new Continents. “Those most valued in the arts,” said he, “are inhabitants of the Mediterranean, and part of the Indian Ocean; two small kinds of sponge thrive even on the frozen shores of Greenland; and forty species have been discovered on the coasts of Great Britain. ”

“ There appears to be a well-marked relation between temperature and the power of spongin-secretion, and as a result we find that sponges with a really well-developed horny skeleton (whether Euceratosa or Pseudoceratosa) are usually only met with in comparatively warm waters. This fact brings about a striking contrast between the sponge-faunas of different latitudes. ”

“ Bhaer, when the settling of stools and rustling of papers had subsided.
Nan took her place beside the little table, and, with a preliminary giggle, read the following interesting essay on
“The Sponge.
“The sponge, my friends, is a most useful and interesting plant. It grows on rocks under the water, and is a kind of sea-weed, I believe. People go and pick it and dry it and wash it, because little fish and insects live in the holes of the sponge; I found shells in my new one, and sand. Some are very fine and soft; babies are washed with them. The sponge has many uses. ”

“ And just as with the coral, it took Folks a long time to find out whether sponges were plants, shrubs, or insects.
Now it is decided that the sponge is an animal growth. And the same as with coral, the tiny creature that it starts from dies, and out from the skeleton, or frame, branches the sponge that sometimes grows very large, and sometimes is of a kind that remains small. One may be as big as a mop, others no larger than an egg. ”

“ It is possible, though direct proof is lacking, that the sponge does good in purifying water used for washing the clothes, utensils, and persons of those who drink the same water, by absorbing decaying animal and vegetable matter from it. ”

“ The water also carries air, and the sponge gets its oxygen out of it. You see, the sponge like the fish, must breathe under water.While the sponge is like an animal, in eating other little animals and plants, it is like a vegetable in that it cannot move around. It is rooted to one spot. The sponges grow so thickly that they often make perfect forests on the rocks, on the bottom of the sea. When the sponge is taken from the water it is covered with what seems to be a mass of jelly. This is its flesh, and the flesh is made up of the little cells with tails that I have been telling you about. ”

“ Murren, sponges must be in a current after they have once taken hold. They can't swim around to get their food, so, like all the fixed forms of life, their food must come to them. If there is no current there is not enough food carried past for them to live on. If the current is too strong the sponge has to make an extra tough skeleton to brace itself against the rush of water and then it becomes too coarse for commercial use. Some of the polyps live on tiny animals with a lot of flint in their shells and the skeleton gets like glass. They call them glass sponges. ”

“ Sponges living in muddy water are often nearly black. This is because the cells of their parenchyma are gorged with very minute solid particles of silt. If a sponge of the kind is kept in clean water for a few days, it often becomes almost white. An interesting experiment is easily performed to illustrate the absorption and final elimination of solid colouring matter by placing a living sponge (small specimens of Spongilla carteri are suitable) in a glass of clean water, and sprinkling finely powdered carmine in the water. ”

“ Sponges of many hues must fairly carpet large areas of the deep water, as the dredge is often loaded with them. The small shore-loving ones which I photographed are in perfect health, but the camera cannot show the many tiny currents of water pouring in food and oxygen at the smaller openings, and returning in larger streams from the tall funnels on the surface of the sponge, which a pinch of carmine dust reveals so beautifully. ”

“ There are many forms who weave a home of far more delicacy and beauty than their more familiar and homely brothers. The sponge creature itself is a slimy, soft creature, which fills in the spaces in its spongy skeleton. It is fastened to one spot, and gathers in its food from the water around it (and oxygen as well) , by means of numerous whip-like filaments called cilia, which flash through the water driving in the food and oxygen to the inner positions of its body. ”

“ A sponge is the skeleton of a very, very, tiny animal, or rather of a colony of thousands of such animals that live under water. When the little animals die they leave behind them this network of elastic fibers that they have built up. For a long time it was thought that sponges were plants, and even now scientists know really very little about these little animals. You have noticed how many kinds of sponges there are. ”