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Homoscleromorpha is phylogenetically well separated from Demospongiae. [4] Therefore, it has been recognized as the fourth class of sponges. [5] [6]It has been suggested that Homoscleromorpha are more closely related to eumetazoans than to the other sponge groups, rendering sponges paraphyletic. [7]
Category: Sponges by classification. 3 languages. ... This category lists animals of the phylum Porifera, sorted by taxonomic classes. Subcategories.
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.
The many diverse orders in this class include all of the large sponges. About 311 million years ago, in the Late Carboniferous, the order Spongillida split from the marine sponges, and is the only sponges to live in freshwater environments. [8]
The algae help facilitate oxygen and food uptake for the sponge, while the sponge provides the algae a surface to live on. The gemmules of Spongilla lacustris inside the original parent sponge. The texture of the sponge itself is soft. The ostia (dermal pores) let water into the sponge to be filtered. The oscula is the hole from which water exits.
Hexactinellida is one of four classes of phylum Porifera. [4] Hexactinellida can exist in many different forms and shapes: sac, vase, blade, and branching. Hexactinellida is distinguished from the other three classes of sponge for its siliceous skeletal arrangements (spicules), triaxonic symmetry (six-rayed spicules or hexactins), and its huge ...
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 .
The siliceous sponges form a major group of the phylum Porifera, consisting of classes Demospongiae and Hexactinellida. They are characterized by spicules made out of silicon dioxide, unlike calcareous sponges. Individual siliachoates (silica skeleton scaffolding) can be arranged tightly within the sponginocyte or crosshatched and fused together.