On the surface, they appear to be ordinary modern marine creatures, but inside, they possess a chromosome structure that has been preserved for 600 million years.
A study led by Dr. Daniel Rokhaer from the Department of Molecular and Cell Biology at the University of California, Berkeley, reveals that these are invertebrates still swimming in many oceans today, including certain species of sponges and jellyfish.
Fire jellyfish Rhopilema esculentum, one of the creatures studied in this research – (Photo: Bill Abbott, Creative Commons License)
New analyses show that the first multicellular animals on Earth carried their genes on 29 pairs of chromosomes. As the first marine animals emerged and evolved into invertebrates from sponges to worms, many of these chromosomes have remained intact for over half a billion years.
The species studied include Branchiostoma floridae, a charming flower-like creature; the pen-like marine organism known as amphioxus; the freshwater sponge Ephydatia muelleri; fire jellyfish Rhopilema esculentum….
At times, we ourselves may carry a portion of these primitive chromosome pairs, which have been “recreated” through numerous rounds of duplication, fusion, and rearrangement.
The paper published in Science Advances suggests that this finding indicates evolution is a conservative process, and even after billions of years, countless generations, and various forms of transformation, many ancient elements will forever link the life of a planet on a complex family tree. They also discovered similar preservation of DNA on chromosomes in some species.
While invertebrates retain their primitive chromosome pairs quite intact, vertebrates like us choose to “mix” them during evolution, Dr. Rokhaer and colleagues added in their publication.
