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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.
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]
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.
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 ]
Using their ostia and osculum these sponges filter the water for various small aquatic organisms such as protozoans, bacteria, and other free-floating pond life. [4] Sponges of the genus Spongilla partake in symbiotic relationships with green algae, zoochlorellae. The symbiotic zoochlorellae give the sponges a green appearance and without them ...
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 ...
Bolosoma stalked glass sponge. 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.
Category: Sponges by classification. 3 languages. ... This category lists animals of the phylum Porifera, sorted by taxonomic classes. Subcategories.