The Turkey sponge, (scientific name Spongia officinalis), commonly known as the bath sponge, is a natural type of sponge widely sold in commerce. It is native to the Mediterranean Sea and can be found in nearby countries.
Even if many people believe it to be a plant, the turkey sponge is actually an animal. Turkey sponge has a grey color when it's alive but it's always sold after it dies in dried form, when it turns either yellow or light brown. The turkey sponge only moves in its larva form, these swim until they find a proper spot. They become attached there, on the sea bottom or another hard surface. The animal has a surprisingly long life and needs up to 40 years to reach the size of a tennis ball. It is hermaphroditic and multiplies through either normal sexual contact or budding. Over harvesting has made it uncommon.
The color of the live turkey sponges found in the wild is variable and can be anywhere from white to black. The turkey sponge appears to be dark when inspected in the sun but lighter when seen on the sea floor. The size and shape are also quite different but it is normally globular, with a diameter of more than 10 cm. The surface is covered with small conules no more than 0.2-0.5 mm long, placed 1-2 mm apart, but otherwise appears smooth. Oscules can only be found in small numbers on the upper side and reach a diameter of about 1 cm.
The turkey sponge lives like a fixed animal but has a flexible internal structure. Turkey sponge is polymorphous and rarely moves at all. It consists of a mass of fibers or small spires that form a dense network, topped by a layer of flesh with a jelly consistency on the outside. The flesh is covered with small orifices that allows sea water to come in and out. Because of the numerous pores or mouths, sponges are today classed in the phylum known as Porifera (also named Spongiaria). In the past, they were included in the colonial Protozoa group, which is the most primitive of all animal classifications. There are two types of pores but both lead inside the various branches of the digestive canals of the bath sponge. The vast majority of these pores are very small, just big enough to allow water to come in.
All along the internal canals there are some larger openings names ciliated chambers. Many small filaments or flagella are located there and produce a permanent current through the canals, which sucks sea water from the surface pores. The sea water is rich in various small organisms that reach the digestive system of the sponge and are the base of its diet. The canals are the key distribution system of the animal and serve many other purposes, the required oxygen is also transported by them, waste is eliminated and the eggs that reproduce the sponge are fertilized in there.
Turkey sponges can be found in warm waters, mainly in the Mediterranean Sea and Red Sea but also in Florida, the Caribbean Islands and along the coasts of Central America. They are located on the sea floor, attached directly to rocks or any other solid objects. The collection and sale of sponges is an important industry in the Greek Islands, as well as Cyprus, Bahamas, the coasts of Asia Minor and North Africa. Sponges have always been in high demand in the USA and large quantities were traditionally imported from the Mediterranean area. Starting in 1852, sponge fishing has begun in the Bahamas and along the coasts of Florida and today most of the US supply comes from these areas.
Live animals are covered with a layer of gelatinous flesh when fished, which is actually part of them but must be removed. Sponges are fished in large quantities in the Bahamas but tend to be rougher than the European ones. The finest specimens come from the Mediterranean Sea, in particular from the Syrian coast. Lately, a method for the commercial cultivation of sponges has been found. The animals are easy to multiply, it only takes cutting a live one under water in small parts, which are then attached on a sandy patch on the sea bottom. The fragments need about three years to grow big enough to be harvested.
The commercially sold sponges look quite different from the actual wild animals. They are light and porous pieces, either yellow or brown in color. Both the size and the shape are variable but all of them consist of a matrix of fine elastic fibers. When taken from the sea, a sponge is usually dirty and full of fragments of other sea creatures like shells or corals, as well as small stones or dried weeds. It must be left for a few days in cold water initially, then beaten up to remove the hard parts inside. The rest of the impurities have to be eliminated by dissolving them in a solution of hydrochloric acid, normally diluted with about 30 parts of water.
The resulting sponge is very clean and can even be used in surgery. It has a very soft surface and can get a lighter color if treated with a mixture of water and sulphurous acid or submerged in chlorine. Only the best specimens, as soft and elastic as possible, should be chosen for surgical purposes. To produce the so-called burnt sponge, any type can be used, including the coarse and bad quality ones.
Turkey sponges have been collected and used in the Mediterranean basin for thousands of years. Sponge mould decorations can be seen on the walls of the so-called house of the queen in Knossos, built sometime in 1900 - 1750 BC, which proves their usage by the ancient Minoan culture of Crete. They were later known by both the Egyptian and Phoenician civilizations. Since ancient times, a sponge could be used for a particular painting technique, by soaking one in paint and leaving random decorative marks on the walls of a house. Greek pottery shows sponges even before the classical era, in bath scenes but also as a luxury item for the rich.
In the Roman Empire, sponges were common and widely used. Several ancient authors described their history and harvesting and used the term spongiare for the process of washing or cleaning with them, which leads to their current name in many languages. Sponges had many uses in the Roman world and ceased to be a luxury item. Even Roman soldiers were supplied with sponges as part of their regular rations, for washing and as a material to stuff their helmets.
Besides their use in hygiene, sponges have been employed in many other ways. Babies were suckled with honey sponges and they were also soaked in very cold and very hot water as a form of early hydrotherapy.
Another interesting usage was as a natural contraceptive. In the old Jewish culture, they were covered in silk and tied on a string to prevent unwanted pregnancy. For a long time, the best contraception method was inserting a sponge soaked in vinegar or lemon juice before sexual contact.
The first usage in surgery appears to date from the middle Ages. Arab surgeon Ibn Al Koff (1232 - 1286 AD) is believed to be the first to commonly use them as an anesthetic, by creating a so-called soporific sponge that served to make the patient inhale its content. This method required some preparation: the sponge was dried in sunlight after being soaked in a combination of plants with a sedative effect that included hashish, hyocymine juice and papaver. During surgery, the sponge was again soaked in water and inserted in the nose of the sick person. The active compounds were thus absorbed by the mucus in the nose and caused sleep during the operation.
European medieval doctors also used sponges in surgery but their method was completely different from the Arab one. The bath sponge was boiled in a recipient with a mixture of plants until all the water was gone and the active compounds were concentrated inside it. The mixture consisted of opium, poison hemlock, green mulberries as well as juices of mandragora and ivy. It was placed in the patient's nose during surgery and another sponge with vinegar was used to revive him after the procedure.
Bath sponges were also eaten as food and had a number of other medical uses. Some varieties from the Tethyae species were thought to cure digestive problems, dysentery, flatulence, sciatica and smelly breath. Homeopathy still uses sponges on a large scale, the most common remedies in traditional treatments are Spongia tosta, Carbo-spongiae and Spongia usta. They can also serve as prostheses with a small size, but this use is uncommon.
The turkey sponges can only grow if the sea is warm and survive up to a depth of 600 feet. They inhabit warm and tropical waters around the globe but are the most common in the Eastern Mediterranean, the Red Sea, Bahamas and the waters around Florida.
Turkey sponges are mainly built from calcium carbonate, normal salt, coagulated albumin and the outer layer of gelatin. The main chemical elements are sodium, potassium, silica, iron, magnesium, sulphur and phosphorus but bromine and iodine have also been detected.