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Spongia officinalis

life science Maturity 11-13 Next article →

Spongia officinalis is a commercially important sea sponge. It is widely known by the common name "bath sponge." This marine organism lives in the Mediterranean Sea. It can be found along many coasts, including those of Greece, Italy, and Spain. These sponges grow on rocky surfaces, sandy bottoms, or vertical walls. They live in well-oxygenated water at various depths. They can be found in shallow water only 1 meter deep. They can also live as deep as 100 meters below the surface.

Bath sponge Spongia officinalis Greece
Bath sponge Spongia officinalis Greece

The physical structure of the sponge is quite complex. It grows in large, globular lobes. These lobes have fine, slightly elevated openings. These openings often have cone-shaped voids called conules. The sponge also has oscula, which are larger openings. These oscula can be scattered or located at the tips of the lobes. The sponge's color ranges from light grey to black. Its shape and strength come from a specialized internal skeleton. This skeleton is made of two different types of fibers.

Bath sponge Spongia officinalis Greece
Bath sponge Spongia officinalis Greece

The skeleton consists of an ectosomal and a choanosomal part. The ectosomal skeleton is made of primary and secondary fibers. These fibers work together to form the conulose openings. The choanosomal skeleton is a dense, irregular mesh of polygons. Primary fibers rise from this mesh. These primary fibers are 50 to 100 nanometers in diameter. They are made of a protein called spongin. They also contain inclusions like sand grains and spicules. Secondary fibers are much smaller, measuring 20 to 35 nanometers in diameter. These smaller fibers consist only of spongin without any inclusions.

Spongia officinalis has several ways to reproduce. It can reproduce asexually through budding or fragmentation. It also reproduces sexually. Some individuals are dioecious, meaning they are either male or female. Other individuals are sequential hermaphrodites. This means they can alternate between being male and female. This change can even happen within a single reproductive season. Sexual reproduction usually peaks between October and November. During this time, sperm is formed in spermatic cysts. The sperm is then free spawned into the water. Females capture the sperm to fertilize their oocytes.

Bath sponge Spongia officinalis Greece
Bath sponge Spongia officinalis Greece

The life cycle follows a specific sequence after fertilization. Embryos develop within the choanosomal tissue of the female sponge. Cell cleavage begins around November. By May, a stereoblastula forms. This is a type of blastula that lacks a clear central cavity. From May to July, parenchymella larvae develop. These larvae are masses of cells wrapped in flagellated cells. They are released from the adult between June and July. These larvae are lecithotrophic. This means they cannot feed themselves. They must rely on energy reserves provided by the mother. They swim for a short time before settling on a benthic surface to grow.

Bath sponge Spongia officinalis Greece
Bath sponge Spongia officinalis Greece

Humans have interacted with this sponge for thousands of years. Carl Linnaeus first described the species in 1759. Aristotle wrote about sponge fishing as early as 350 BC. In ancient times, Greeks used sponges for many tasks. During the Middle Ages, the use of sponges spread across Europe. Roman soldiers even used sponge padding in their helmets. Sponges were also used as absorbent material in surgeries. They were used in medicine for digestive issues. They were even used as a primitive contraceptive. Today, people use them for washing or for sponge painting.

Bath sponge Spongia officinalis Greece
Bath sponge Spongia officinalis Greece

Fishing methods have changed as technology improved. Traditionally, Greeks dove underwater to collect sponges. In the late 19th century, a new diving suit was invented. However, these suits were not very safe. Between 1910 and 1930, new underwater breathing devices were created. This led to a steady increase in sponge fishing. Today, populations face threats from over-harvesting and disease. Pathogenic bacteria and fungi can destroy sponge tissues. This makes the sponges weak. To help, people use sponge farming. This started in the Mediterranean in the late 19th century. Farmers attach sponge fragments to wooden boxes. Farming reduces stress on wild populations. It also helps clean the water by removing organic particles.

Bath sponge Spongia officinalis Greece
Bath sponge Spongia officinalis Greece
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