Origination of Sponges

Our world was once a different one
Millions of years ago
Just how the sponges fared
No one will really know

As to the precise and accurate origin of sponges, no scientist is quite certain. They are neglected in the usual progression of the animal fossil history. It seems that they have very minimal connections to modern species, and they only remain members of the animal kingdom by other criteria. Their history is cryptic, and there are significant "holes" in the fossil record. However, with more research and compilation of research, it is hoped that someday we will unlock the door to the numinous history of porifera. Interestingly, sponges are a junction of protist and metazoan organisms that gradually converged to produce the first porifera. The choanoflagellates were critical in the creation of sponges. Choanoflagellates are a division of protists, comprising about one hundred fifty species. Their primitive structure constrains biodiversity. Like choanocytes, each choanoflagellata consists of whip-like flagellum, protected by a collar of closely-woven microvilli. With the pulsation of the flagellum, water and food are drawn towards the organism. The microvilli filter the bacteria within the water, be it marine or fresh. They may have free locomotion, or they may be attatched to the substratum, rendering themselves sessile. Their fossil record, not very accurate, suggests that they existed during the late Precambrian, and they are the most logical protist relative of the metozoan sponges. Modern representations of choanoflagellata are still existent today.

However, in 1996, a fossil record of the first sponge was discovered near Australia. This species, denoted as Paleophragmodictya, bore the ramifications of a spicule net system. Such related it distinctly to the Hexactinellids. It is theorized that hexactinellids originated before all the other sponges within the late Proterozoic. While some scientists suggest that Hexactinellids should be severed from the porifera phylum into their own phylum known as Symplasma, it is less complex if they remain within the porifera phylum until more substantiated knowledge is developed.

The other classes of sponges developed at later times. The earliest specimens of the Demosponges date back to the Cambrian, as do the Calcareous. Various members of the Sclerospongiae were created at different intervals before the Cretaceous.