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American Scientists believe that Sea Sponges were the first ever animal that appeared on the Earth. This discovery of the Massachusetts Institute of Technology (MIT) team is based on the analysis of molecular fossils that were obtained from rocks that still exist and are 640 million years old.
‘Cambrian explosion’ is an evolutionary period which began around 640 million years ago. During this period, a wide range of new animal species appeared on the earth for the first time. Researches undertaken at the reputed MIT have come out with the findings that the sea sponges pre-dated this period.
How was the discovery made
A kind of molecule, 24-IPC or 24-Isopopylcholestrol, known to be produced by sea sponges today, has a trace of it in the 640 million years old sample rock analysed by the researchers.
Based on this newly found evolutionary lead, the team headed by David Gold researched further to find out the particular gene that generated the 24-IPC molecules and when it had evolved in the organisms that carried the gene.
The team shortlisted about 30 organisms and found that a single gene known as Sterol Methyltransferase (SMT) can make an organism produce 24-IPC, though it depended on how many copies of the gene it had.
They found that sea sponge and an algae species, both had correct number of copies of SMT for producing 24-IPC.
A further analysis of these genes and by making evolutionary trees on the basis of the fossil record, they could find that quite earlier to algae, the sea sponges were producing the 24-IPC molecules.
The scientists thus found enough evidence to conclude that the sea sponges existed on the earth, much earlier to any other kind of animals.
Unraveling the past
David Gold believes that this discovery will lead to more questions to be answered; such as how did these animals look like? How was the environment then? Why such a big gap in the recording of the fossil? This discovery leads us to believe that a lot of things are yet to be known about animal life that calls for more studies in this regard.
What are sea sponges?
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Although they may look plant-like, sponges are the simplest of multi-cellular animals. A sponge is a bottom-dwelling creature which attaches itself to something solid in a place where it can, hopefully, receive enough food to grow. The scientific term for sponges is Porifera which literally means “pore-bearing.”
Sponges are very effective filter feeders, since they are able to capture and eat particles as small as bacteria as well as much larger particles.
Here’s an interesting video on sea sponges,
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