Practically everybody is familiar with the common sponge, as there are few families or individuals, living in civilised countries, who do not use it on various occasions. So very useful has this ordinary every day article become that we should experience no little inconvenience if for any reason we were unable to obtain it. What would the surgeon, for example, do without it when he is performing an operation? What would the housekeeper do? How much less should we enjoy our bath if the sponge were not available! And yet, despite the fact that a sponge is to be found in almost every household, how many people know what a sponge really is?
It has become so much an article of everyday use that we never trouble to ask ourselves concerning its origin, its pedigree, or its home. If you were to ask anyone this question: "What is a sponge?” you would be met with a blank look of amazement, because very few people have ever read anything about the sponge. Some would probably be able to state that sponges are obtained from the bed of the sea or ocean, and their knowledge would, no doubt, be limited to that single fact.
What is a sponge? For a great many years this question puzzled scientists, and for a long time the sponge was regarded as being a form of plant life. There appeared to be good reasons for classifying it with the vegetable world, because, in form, the sponge is in many ways like a plant, and also because it is fixed to a particular spot just as an ordinary plant is kept in a certain position in the soil by means of the root.
It was not until the year 1829 that a scientist, named Grant, carried out a number of careful observations of the habits of these remarkable creatures, and discovered their method of feeding. His investigations of sponge life led him to assert that sponges, although fixed to one spot, really belong to the animal and not to the vegetable kingdom. Since then, further scientific observations have been made and their structure has been closely examined, so that nowadays scientists are fully agreed that sponges must be classified with the lower forms of animal life.
One end of the sponge is fixed to the bed of the sea, while the other end is open. This opening is known as the osculum. The walls of the sponge are penetrated by innumerable small canals. Currents of water, passing through the smaller pores and out at the larger openings, contain a variety of still lower forms of life on which the sponge makes its meal.
In its natural state, on the floor of the sea or ocean, the sponge is a living thing, but the sponge that is sold as a commercial commodity is but the framework or skeleton of the original living creature. When the sponge is alive, the skeleton is coated with a sticky kind of matter of a gelatinous nature, and before the sponge can be of any marketable value this soft, sticky portion must be entirely removed. There are various ways of doing this, according to the locality in which the sponge is found. In the Bahamas, for instance, the soft animal matter is beaten out by the natives with flat pieces of wood that resemble small paddles.