Species of the order Baerida are leuconoid calcareous sponges with the skeleton either composed exclusively of micro-diactines, or in which microdiactines constitute exclusively or predominantly a specific sector of the skeleton, such as choano-skeleton or atrial skeleton. Large or giant spicules are frequently present in the cortical skeleton, from which they can partially or fully invade the choanoderm. In sponges with a reinforced cortex, the inhalant pores can be restricted to a sieve-like ostia-bearing region. Dagger-shaped small tetractines (pugioles) are frequently the sole skeleton of the exhalant aquiferous system. Although the skeleton may be highly reinforced by the presence of dense layers of microdiactines in a specific region, an aspicular calcareous skeleton is not.[citation needed]
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.
Leucosolenida is an order of sponges in the class Calcarea and the subclass Calcaronea. Species in Leucosolenida are calcareous, with a skeleton composed exclusively of free spicules without calcified non-spicular reinforcements.
Demosponges (Demospongiae) are the most diverse class in the phylum Porifera. They include greater than 90% 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.
Clathrina is a genus of calcareous sponge in the family Clathrinidae. Several species formerly in Clathrina were transferred to the newly erected genera Arturia, Ernstia, Borojevia, and Brattegardia in 2013. The name is derived from the Latin word "clathratus" meaning "latticed".
The Murrayonida are an order of sea sponges in the subclass Calcinea.
Minchinellidae is a family of calcareous sponges, members of the class Calcarea. It is the only family in the monotypic order Lithonida. The families Petrobionidae and Lepidoleuconidae have also sometimes been placed within Lithonida, though more recently they have been moved to the order Baerida. Thanks to their hypercalcified structure, minchinellids have a fossil record reaching as far back as the Jurassic Period.
Levinellidae is a family of calcareous sponges in the order Clathrinida. It contains the following genera and species:
Achramorphidae is a family of calcareous sponges in the order Leucosolenida.
Jenkinidae is a family of sea sponges in the order Leucosolenida.
Homosclerophorida is an order of marine sponges. It is the only order in the monotypic class Homoscleromorpha. The order is composed of two families: Plakinidae and Oscarellidae.
Trichogypsia is a genus of calcareous sponges in the order Baerida.
Ascute asconoides is a species of calcareous sponge found in Australia.
Ascute uteoides is a species of calcareous sponge found in Australia.
Borojevia is a genus of calcareous sponge in the family Clathrinidae. The genus is named after sponge researcher Radovan Borojevic.
Baeriidae is a family of calcareous sponges in the class Calcarea. It was named by Borojevic, Boury-Esnault, and Vacelet in 2000. The type genus is BaeriaMiklucho-Maclay, 1870, by original designation, though Baeria is now considered a junior synonym of LeuconiaGrant, 1833.
Trichogypsiidae is a family of sponges in the class Calcarea.
Soleneiscus is a genus of calcareous sponges in the family Dendyidae.
Leuclathrina is a genus of sponges belonging to the family Dendyidae. Species are found in the northeast Atlantic and in the Indian Ocean.
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.
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