According to a recent study published in Nature, researchers think they may
have discovered the first species to have walked the Earth 700 million years
ago.
According to a
press release
from the University of California Berkeley, scientists
concluded
that the first animal was probably a comb jelly, or ctenophore – a predator
that scours the water for prey.
Comb jellies, although looking like jellyfish, are quite different from
them and move through the water on their cilia rather than their tentacles.
They may be found in seas all around the world and are still a vital
component of the marine ecology.
"All living things share a recent common ancestor that existed around 600
to 700 million years ago. Because they were soft-bodied and didn't leave a
direct fossil record, it's difficult to tell what they were like, according
to co-author of the research and UC Berkeley professor Daniel Rokhsar. But
we can find out about our shared ancestry by making similarities between
live species.
The question of whether the sponge or the ctenophore evolved first has been
debated for a long time, according to the university. The majority of their
lives are spent in one location, as sponges filter water via their pores to
gather food particles.
Many have suggested that the sponge emerged first — before the ctenophore —
because of its basic traits, according to experts. While sponges arrived
first, according to this new research, ctenophores probably came
second.
Scientists examined how the genes were arranged in the creatures'
chromosomes to come to that conclusion. The chromosomes of the ctenophore
differ significantly from those of sponges, jellyfish, and other
invertebrates, indicating to scientists that the ctenophore may have evolved
much earlier or much later than the others.
"At first, we couldn't tell if ctenophore chromosomes were different from
those of other animals simply because they'd just changed a lot over
hundreds of millions of years," Rokhsar said in the press release. The third
possibility is that they diverged first, before any other animal lineages,
and as a result are unique. We have to resolve the issue.
When scientists compared the chromosomes of ctenophores to non-animals, it
was the "smoking gun" for them.
According to a news release, the team's analysis of the chromosomes of
these various animals and non-animals revealed that while ctenophores and
non-animals shared specific gene-chromosome combinations, sponges and other
animals' chromosomes were rearranged in a totally different way.
Researchers claim that the new understanding is important for understanding
the foundational behaviors of all animals and humans today, including how we
move, consume, and detect our immediate environment.
