"Starfish bodies aren't bodies at all, study finds"As per the article:
"The heads of most animals are easily identifiable, but scientists haven’t been able to say the same for sea stars until now.
A starfish has five identical arms with a layer of “tube feet” beneath them that can help the marine creature move along the seafloor, causing naturalists to puzzle over whether sea stars have defined front and back ends — and if they have heads at all.
But new genetic research suggests the opposite — that sea stars are largely heads that lack torsos or tails and likely lost those features evolutionarily over time. The researchers said the bizarre fossils of sea star ancestors, which appeared to have a kind of torso, make a lot more sense in evolutionary terms in light of the new findings.
The findings were published Wednesday in the journal
Nature.
“It’s as if the sea star is completely missing a trunk, and is best described as just a head crawling along the seafloor,” said lead study author Laurent Formery, postdoctoral scholar at Stanford University and the University of California, Berkeley, in a statement. “It’s not at all what scientists have assumed about these animals.”
The revelations, made possible by new methods of genetic sequencing, could help answer some of the biggest remaining questions about echinoderms, including their shared ancestry with humans and other animals that look nothing like them."
Well, since it should be perfectly obvious that a starfish isn't really a "fish," I suppose it's not too surprising that they don't really have "arms" either. Still, it did take modern genetic sequencing to bring it to a head.
Here's the link:
https://www.cnn.com/2023/11/02/world/starfish-head-body-plan-scn/index.html