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.
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.
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.