this feels kinda silly, like surely we’re the ones defining what the head is here? head and body doesn’t make sense for a starfish, it’s like asking where the head of a potato is
So somebody went and looked at its genetic structure, and compared its structure as it developed from larva and found that each of the limbs (if I understand it correctly) are all head (or heads,) and the tail disappears.
No, it’s not English semantics they are using here. It’s DNA semantics. They looked for DNA markers and gene expression to define what is head or tail of various animals, and found that most of the starfish expressed those similarly to the head of other animals.
One of the previous theories had the head in the middle and tail at the edge of the arms. But this study showed that the DNA markers for “head” are expressed all through the starfish, and there are no “tail” markers at all.
So what I’m getting here is that they basically proved that Starfish evolved from a clade that predates the development of basically everything we consider an animal save for spongeoforms
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