… like, less complex animals like sponges descended from more complex animals like comb jellies.
Your evolution textbook never told you that. Or anything like it. Pretty much told you the opposite. Still, you believe. 😉
Sponges have been generally considered our most ancient animal relatives. But that title may actually belong to members of the anatomically more complex phyla Ctenophora, or comb jellies, according to a report published today (December 12) in Science. This family tree reshuffle has come about thanks to the whole-genome sequencing of the comb jelly Mnemiopsis leidyi.
“If the split between Ctenophores and all other animals was the earliest split in animal evolution, it suggests some unintuitive facts about evolution,” said Finnerty. “For example, that sponges, which are very simple animals that lack a nervous system and lack muscle cells, actually came from an ancestor that had those features.” Ctenophores, he explained, “tend to be really active animals—they are swimmers, they have smooth muscle, they have a nervous system, they prey on zooplankton. . . . They would seem to be representative of a much more complex condition, anatomically and behaviorally.”
Consequently, the suggestion that the Ctenophora might be the earliest branch of the animal family tree “was and has remained controversial,” said Andy Baxevanis, who is head of the Computational Genomics Unit at the National Human Genome Research Institute and led the new study. “It became obvious to us that having a whole genome sequence for the Ctenophores would go along way to resolving the issue.”
Actually, having genome sequences for all Ctenophores might—or might not—go a long toward resolving the issue. It coul render the issue unresolvable against current background assumptions.
More information resolves a problem if we have it by the right handle but lack information about certain parts. However, if—as increasing numbers of researchers are saying—we need to rethink the whole concept of a tree of life, lots more information will mean lots more information that doesn’t fit the old ideas.
Remember, Darwin thought that if only we had more information about the Cambrian period, the problems it posed to his theory would go away. Famously, that never happened, except in the imaginations of his modern day followers, for whom nothing could be a problem except Darwin’s doubt.
See also: Animal that stages light display is 600 million years old? And yes, it is a comb jelly.
Sea creature, nearly 600 mya, wobbles current classifications of life “A 580-million-year-old fossil is casting doubt on the established tree of animal life.” – Nature