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The calcareous sponges[2][3] (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 high- magnesium calcite or aragonite. While the spicules in most species are triradiate (with three points in a single plane), some species may possess two ...
The shapes of calcareous sponge spicules are simple compared with the sometimes very elaborate siliceous spicules found in the other sponge classes. With only a few exceptions, calcareous sponge spicules can be of three basic types: monaxonic, two-tipped diactines, triactines with three spicules rays, and four-rayed tetractines.
Sponges were traditionally distributed in three classes: calcareous sponges (Calcarea), glass sponges (Hexactinellida) and demosponges (Demospongiae). However, studies have now shown that the Homoscleromorpha, a group thought to belong to the Demospongiae, has a genetic relationship well separated from other sponge classes.
Clathrina coriacea is a species of calcareous sponge belonging to the class Calcarea and family Clathrinidae. [ 1] Species in the genus Clathrina are composed of calcium carbonate tube-like skeletons containing spicules. [ 2] The sponge can be located in shallow waters widely distributed along North Atlantic coasts, as well as on other coasts.
Hexactinellid sponges are sponges with a skeleton made of four- and/or six-pointed siliceous spicules, often referred to as glass sponges. They are usually classified along with other sponges in the phylum Porifera , but some researchers consider them sufficiently distinct to deserve their own phylum, Symplasma .
Nicholson & Murie, 1878. Stromatoporoidea is an extinct clade of sea sponges common in the fossil record from the Middle Ordovician to the Late Devonian. [1] They can be characterized by their densely layered calcite skeletons lacking spicules. Stromatoporoids were among the most abundant and important reef-builders of their time, living close ...
Sclerocyte. Sclerocytes are specialised cells that secrete the mineralized structures in the body wall of some invertebrates. In sponges they secrete calcareous or siliceous spicules which are found in the mesohyl layer of sponges. The sclerocytes produce spicules via formation of a cellular triad. The triad of cells then undergo mitosis ...
Calcareous is used as an adjectival term applied to anatomical structures which are made primarily of calcium carbonate, in animals such as gastropods, i.e., snails, specifically in relation to such structures as the operculum, the clausilium, and the love dart. The term also applies to the calcium carbonate tests of, often, more-or-less ...