A recent study has revealed that Sea sponges are likely the first animals on planet earth. Sea sponges are said to have appeared on earth over 640 million years ago.
For billions of years, rudimentary building blocks of life have been in existence on earth. Over a long period of time, these pieces reorganized themselves to form the present life forms. Researchers from the Massachusetts Institute of Technology (MIT) have unraveled evidence suggesting that sponges were likely the first animals to exist on earth.
Molecule discovered before Cambrian Explosion linked to sponges
Led by Dr. David Gold Prof and Prof. Roger Summons both from MIT, the scientists discovered an unusual molecule in rock samples that are approximated to be over 640 million years old. The researchers linked this molecule to sponges. 640 million years ago is approximately 100 million years before the Cambrian Explosion – an era where most animals started emerging.
In the research published in the journal “Proceedings of the National Academy of Sciences”, Dr. Gold says that certain evidence shows that some animals appear to be likely older than the Cambrian Explosion. This, therefore, drives the interest of determining and studying biomarkers, molecules and chemicals’ evidence left to help solve such mysteries.
Back in1994, scientists found a certain molecule – 24-isopropylcholestane (24-ipc) in Cambrian and other older rocks. They speculated the molecule to have originated from sponges. Later on in 2009, 24-ipc was also discovered in rock samples from Oman estimated to be over 640 million years old. This potentially gave evidence for the oldest animal life forms.
Research reveals that certain algae types and modern sponges produce 24-ipc in the modern times. After a series of genome studies on various organisms, sponges included, Gold and his team identified a gene called sterol methyltransferase (SMT). Further studies revealed that algae species and Sea sponges that produce 24-ipc contain an additional SMT gene copy.
The researchers went deeper into the evolutionary sequence basing on fossil records and determined that sponges evolved much earlier than algae. They found that the sponges had the extra SMT copy over 640 million years ago, which was the same period that the 24-ipc molecule was discovered in rocks.
Sponges mean “pore bearer”
Sponges are multicellular organisms having pores and channels on their bodies. Water circulates through these channels to supply food and oxygen to these creatures and also remove excretory wastes as they lack digestive, nervous and circulatory systems. Sponges are sessile and are purely aquatic. Most of these organisms are of marine species though there are a few freshwater species in existence. The bodies of these organisms have a jelly-like middle layer between the two layers of cells that make their structures.
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