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| Calcarea | Demosponges | Hexactinellida | Sclerospongiae | Whole Family Tree Listed | Home | ||
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Comprising 90 percent of species With a geologic history Full of perplexities For if you dip a demosponge In a bleach solution Watch it disintegrate Into a liquid convolution
Having originated relatively with the Calcarea and Sclerospongiae, in the Cambrian period, the demonsponges are not as progressively ancient as the Hexactinellids. In geologic history, diversity was at its peak for this class during the Cretaceous. Interestingly, its fossil history is extremely perplexing. Due to their predominately silica structure, it is theorized that many demosponges did not fossilize. Instead, they dissolved with time. In current times, various taxonomical divisions represent significant stages in evolution or extreme diversity. These are reflections of the past that is not able to be visualized through fossils. In Ceractinomorphs, there are convoluted symmetric shapes. Hadromerida genera (the subclass is Tetractnomorphida) generate a distinct type of larva which demonstrate the immense diversity of this class that contains an approximate 90% of all of about 5,000 known species of porifera.
Demosponges are extremely diverse. The class maintains structures only of the leuconoid grade, which is the most complex. Generally, the spicules are composed of silica or spongin. There are frequently combinations of these substances, but the genus Oscarella is noted for the fact that it possesses neither of these in its composition. However, it is generally confirmed that the spicules are one to four rays, diverting from right angles. Additionally, it attributes to itself a myriad of color spectrums. Not to mention, all fresh water porifera are distributed amongst the demonsponges. Such a promulgation influences depth. For example, the subclass Homoscleromorpha may be situated at tidal depths to depths of 500 meters below the surface. The subclass Ceractinomorpha has manifested itself at depths of 7000 meters!
Also, for some miscellaneous facts, demosponges are the only class of porifera implemented for commercial sponges. Also, their structure can eventuate in an intriguing chemical reaction by the following steps: 1) Wash a small fragment of a demosponge with water. 
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