The calcareoussponges are members of the animal phylum Porifera, the cellular sponges. They are characterized by spicules made of calcium carbonate, in the form of high-magnesium calcite or aragonite. While the spicules in most species are triradiate, some species may possess two- or four-pointed spicules. Unlike other sponges, calcareans lack microscleres, tiny spicules which reinforce the flesh. In addition, their spicules develop from the outside-in, mineralizing within a hollow organic sheath.
Demosponges (Demospongiae) are the most diverse class in the phylum Porifera. They include 76.2% of all species of sponges with nearly 8,800 species worldwide. They are sponges with a soft body that covers a hard, often massive skeleton made of calcium carbonate, either aragonite or calcite. They are predominantly leuconoid in structure. Their "skeletons" are made of spicules consisting of fibers of the protein spongin, the mineral silica, or both. Where spicules of silica are present, they have a different shape from those in the otherwise similar glass sponges. Some species, in particular from the Antarctic, obtain the silica for spicule building from the ingestion of siliceous diatoms.
The Treatise on Invertebrate Paleontology published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and covering every phylum, class, order, family, and genus of fossil and extant invertebrate animals. The prehistoric invertebrates are described as to their taxonomy, morphology, paleoecology, stratigraphic and paleogeographic range. However, taxa with no fossil record whatsoever have just a very brief listing.
Baerida is an order of sea sponges in the subclass of Calcaronea, first described in 2000 by Radovan Borojevic, Nicole Boury-Esnault and Jean Vacelet. Baerida contains four families; two of these families were formerly placed within the order Lithonida.
Borojevia aspina is a species of calcareous sponge from Brazil. The species name refers to the lack of spines in the apical actine.
Borojevia brasiliensis is a species of calcareous sponge from Brazil, from which the species' name is derived.
Borojevia cerebrum is a species of calcareous sponge from the Mediterranean Sea. The species name refers to the brain-like appearance of the sponge.
Clathrina cylindractina is a species of calcareous sponge from Brazil. The species is named after the cylindrical-shaped actines the sponge possesses.
Arturia dubia is a species of calcareous sponge in the genus Arturia from Australia. The species was first described as Leucosolenia dubia by Arthur Dendy in 1891. The name is derived from Dendy's uncertainty about the validity of the species, believing his specimens could, in fact, represent juvenile Leucosolenia cavata.
Ascaltis gardineri is a species of calcareous sponge in the family Leucascidae from India and the Seychelles. The species is named after the British zoologist John Stanley Gardiner.
Arturia hirsuta is a species of calcareous sponge from South Africa. The name refers to the hispid surface of the sponge.
Clathrina hispanica is a species of calcareous sponge from Spain. The species is named after the country of Spain, where it was discovered.
Clathrina lacunosa is a species of calcareous sponge from the British Isles. The species name means "having holes" and refers to the perforations found in the sides of the sponge. It is usually found on vertical solid surfaces at depths down to 220 m. It is distributed in the north-eastern Atlantic from the Arctic to the Mediterranean. It is a fairly common sponge but is often overlooked due to its small size.
Arturia sueziana is a species of calcareous sponge from Egypt. The species is named after the Egyptian city of Suez where the holotype was discovered.
Spicules are structural elements found in most sponges. The meshing of many spicules serves as the sponge's skeleton and thus it provides structural support and potentially defense against predators.
Heteractinida is an extinct grade of Paleozoic (Cambrian–Permian) sponges, sometimes used as a class or order. They are most commonly considered paraphyletic with respect to Calcarea, though some studies instead argue that they are paraphyletic relative to Hexactinellida. Heteractinids can be distinguished by their six-pronged (snowflake-shaped) spicules, whose symmetry historically suggested a relationship with the triradial calcarean sponges.
Calcifibrospongiidae is a family of sponges belonging to the order Haplosclerida. The order Haplosclerida is distinguished by isodictyal skeleton. In general, Porifera are basal animals with bodies full of pores and channels. Calcifibrospongiidae includes the species Calcifibrospongia actinostromarioides. There have only been ten recorded occurrences of this species: in Hogsty Reef and San Salvador, as well as in the subtropics of the Bahamas.
Sphaerocoeliidae is an extinct family of calcareous sponges, the only family in the monotypic order Sphaerocoeliida. Sphaerocoeliids are one of several unrelated sponge groups described as "sphinctozoans", with a distinctive multi-chambered body structure. Sphaerocoeliids persisted from the Permian to the Cenomanian stage of the Cretaceous, a longer period of time than most other "sphinctozoans". Sphaerocoeliids make up the majority of calcareous "sphinctozoans", as well as a large portion of post-Triassic "sphinctozoan" diversity. "Sphinctozoans" and the similar "inozoans" were historically grouped together in the polyphyletic order Pharetronida.
Stellispongiida is an order of calcareous sponges, most or all of which are extinct. Stellispongiids are one of several unrelated sponge groups described as "inozoans", a name referring to sponges with a hypermineralized calcitic skeleton independent from their spicules. Stellispongiids have a solid skeleton encasing calcite spicules arranged in trabeculae. "Inozoans" and the similar "sphinctozoans" were historically grouped together in the polyphyletic order Pharetronida.
