More than 5,000 different species of sponges exist worldwide, but only about 15 have some economical importance. Four classes of sponges can be identified: The Calcarea (calcareous spicules); the Hexactinellidae (six-rayed siliceous spicules); the Demospongiae (siliceous spicules, but not six-rayed) and the Sclerospongiae (massive limey skeleton composed of calcium carbonate, siliceous spicules and organic fibres).
Table 1. Main commercial sponges
| Scientific name | Commercial name | Fishing area |
| Hippospongia communis | Horse Sponge, Honeycomb | Mediterranean |
| H. gossypina | Velvet | Gulf of Mexico, Caribbean |
| H. lachne | Wool, Sheepswool | Gulf of Mexico, Caribbean |
| Spongia agaricina | Elephant ear | Mediterranean |
| S. barbara | Yellow | Gulf of Mexico, Caribbean |
| S. graminea | Glove, glass | Gulf of Mexico, Caribbean |
| S. officinalis adriatica | Bathing sponge | Mediterranean |
| S. officinalis mollissima | Turkey cup, Turkey solid | Mediterranean |
| S. petusa | Reef Sponge | Caribbean |
| S. tubulifera | Reef Sponge | Caribbean |
The Demospongiae is the largest class and all species of some commercial value belong to this group. The commercial sponge is the macerated and dried skeleton of a sponge. The commercial value of the sponges comes from their great internal surface, thus they can absorb water up to 20 – 35 times their weight. Sponges from the genera Spongia and Hippospongia have been used for thousands of years for personal and household purposes (Tab. 1). Sponge fishing took place in Greece and Tunisia as long as 4,000 – 5,000 years ago. As natural sponges are resistant to acids and tougher and easier to clean than artificial sponges they are still essential in pottery, surgery, for painting, polishing, filtering, etc. While during the years of high production of natural sponges - in the 1930's - about 70% of the production was used for industrial purposes, the decline of landings in recent years combined with a sharp price increase led to an almost exclusive use of sponges as bath sponges.
| Hippospongia communis | FAO names: | Engl.: Honey comb |
| Fre.: Eponge commune | ||
| Span.: Esponja comun |
Characteristics: Voluminous sponge, with oscula (large openings) irregularly distributed
on the surface. Oscula have a diameter of 0.06 mm to 0.1 mm, ostia (small pores) have a
diameter of 0.025 to 0.03 mm. The sponge is passed through by a meander of large water
canals.
Colour: Blackish grey or yellowish white on the surface, often orange or brown in the
interior.
Size: Maximum diameter can exceed 30 cm.
Habitat: Normally between 0.5 and 30 m depth.
Economic value and usage: This species is the most common sponge in the Mediterranean.
It is used for cosmetic and domestic purposes (bath sponge) and in certain industries. Its
value is below that of the Spongia officinalis (both subspecies adriatica and mollissima), as
its texture is not as fine.
| Hippospongia lachne | FAO names: | Engl.: Sheepswool sponge |
Characteristics: The representative shape of H. lachne is that of a bun, round, but with a
greater horizontal than vertical dimension. The oscules are generally 12 to 18 mm in
diameter, about 6 – 12 per sponge, always on the upper surface.
Colour: The colour in life is a sepia brown.
Size: The larger specimens may be over 30 cm wide and 18 cm high.
Habitat: 2 – 10 m depth.
Distribution: Rock Islands, Cuba, Mexico and Honduras.
Economic value and usage: This species is the best sponge collected in the Western
Atlantic, however of a quality below those of the Mediterranean.
| Spongia agaricina | FAO names: | Engl.: Elephant ear |
| Fre.: Oreille d'elephant | ||
| Span.: Oreja de elefante |
Characteristics: Formed like an ear.
Colour: Grey to brown.
Size: It rarely exceeds 50 cm in diameter, though species with 1 m diameter are reported.
Habitat: Normally between 5 and 60 m deep.
Economic value and useage: No cosmetic usage due to its form, at present mainly
marketed for its decorative value. In the past used as a polisher. Very limited exploitation.
| Spongia barbara | FAO names: | Engl.: Yellow sponge |
Characteristics: The shape of a yellow sponge is spherical or speroidal. The surface is
finely conulose. Each specimen generally has 10 – 20 oscules on its uppermost surface,
each 7 – 10 mm in diameter.
Colour: The colour in life is dark sepia, almost black, when it grows at depths less than 2
m, at a depth of 10 m the colour is yellowish-grey. The fibers of a processed yellow
sponge are more yellowish than those of other commercial sponges.
Size: The larger specimens can exceed 25 cm.
Habitat: 2 – 15 m depth
Distribution: Florida Keys
Economic value and useage: Usage as bath sponge but considered to be of lower quality
than the Mediterranean sponges and the Sheepswool sponge.
| Spongia graminea | FAO names: | Engl.: Glove sponge, Key grass sponge |
Characteristics: The shape of this species is much like that of a truncated cone, with a
base slightly smaller than the rather level upper surface. The very small pores are
confined to the sides of the sponge which are very finely conulose. The pores lead
horizontally inward to a large number of canals, with a diameter of almost 1 cm.
Colour: The dermis is black and the interior is brown.
Size: 12cm diameter normal, some specimen with 25cm diameter.
Habitat: 2 – 5 m depth, a few specimens may be found in deeper water, but these are
small.
Distribution: Florida Keys and Bahamas.
Economic value and usage: Very soft and not very resistant, therefore little commercial
usage.
| Spongia officinalis adriatica | FAO names: | Engl.: Greek bathing sponge |
| Fre.: Eponge fine grecque | ||
| Span.: Esponja de bano griega |
Characteristics: Sponge of various forms and shapes, generally round. Oscula (diameter 3–
10 mm) often protrude from the surface.
Colour: Varies from yellowish white to black depending on the depth of water, the
interior is white.
Size: Maximum diameter can exceed 35 cm.
Habitat: Normally between 0.5 and 40 m depth.
Economic value and usage: Generally considered as an excellent bath sponge, mainly
produced in Greek waters. Quite rare and expensive.
| Spongia officinalis mollissima | FAO names: | Engl.: Turkey cup |
| Fre.: Eponge fine syrie | ||
| Span.: Esponja de bano siria |
Characteristics: This subspecies differs from S. officinalis adriatica due to its form which
is generally a reversed cone.
Colour: Varies from yellowish white to black depending on the depth of water, the
interior is white.
Size: It rarely exceeds 15 to 20 cm in height.
Habitat: Normally between 10 and 30 m depth.
Economic value and usage: Generally considered as the finest bath sponge of the
Mediterranean, but hardly exploited.
| Spongia tubilifera or S. pertusa or S. obliqua. | FAO names: | Engl.: Reef sponge |
Characteristics: The shape is massive, with flat or plane areas at obtuse angles to one
another. The surface is finely conulose. The entire lateral surface of the sponge is
crowded with pores that are less than 1 mm in diameter. The obscules are only 3 – 4 mm
in diameter, and are located on the upper surface.
Colour: Black in life.
Size: 10 cm maximum.
Habitat: 2 – 10 m depth.
Distribution: Caribbean.
Economic value and usage: Generally tough and not very elastic sponges, little commercial value.
