''Clathrina clathrus'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

calcareous sponge The calcareous sponges of class Calcarea are members of the animal phylum Porifera, the cellular sponges. They are characterized by spicules made of calcium carbonate in the form of calcite or aragonite. While the spicules in most species hav ...

belonging to the family

Clathrinidae Clathrinidae is a family of calcareous sponges in the order Clathrinida. It contains the following genera: ''Arturia'' '' Borojevia'' '' Brattegardia'' ''Clathrina'' ''Ernstia ''Ernstia'' is a genus of calcareous sponges in the family Clathr ...

. This yellow (occasionally white) sponge, up to 10 cm in diameter, usually appears cushion-shaped at a distance (its close relative '' Clathrina coriacea'' is normally flatter in appearance). Close-up the sponge can be seen to consist of a tangled mass of tubes (these tubes are thicker and less tightly knit than in ''C. coriacea'' and there is no

osculum The osculum (plural "oscula") is an excretory structure in the living sponge, a large opening to the outside through which the current of water exits after passing through the spongocoel. Wastes diffuse into the water and the water is pumped thr ...

as found in that species). Like ''C. coriacea'', the

spicules Spicules are any of various small needle-like anatomical structures occurring in organisms Spicule may also refer to: *Spicule (sponge), small skeletal elements of sea sponges *Spicule (nematode), reproductive structures found in male nematodes ( ...

are exclusively three-pointed ''triactines''. This is a shallow-water species found in the Mediterranean and on Atlantic coasts of Europe as far north as the

British Isles The British Isles are a group of islands in the North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner and Outer Hebrides, the Northern Isles, ...

References

''Clathrina clathrus'' at Marine Species Identification Portal

External links

* Clathrina Sponges described in 1864 Fauna of the British Isles Taxa named by Eduard Oscar Schmidt {{calcarea-stub