Despite what it looks like, researchers found recently that starfish don’t have limbs that are hugging the surface they touch — the characteristic starfish is actually mostly “just a head.”
What did researchers learn about starfish limbs?
Scientists from England’s University of Southampton found that starfish appear to be missing the genetic code that make up a torso, arms or legs, according to the study published in science journal Nature recently.
“It’s as if the sea star is completely missing a trunk, and is best described as just a head crawling along the seafloor,” Laurent Formery, a Biohub-funded postdoctoral scholar and lead author of the new study, said in a release. “It’s not at all what scientists have assumed about these animals.”
Another researcher confirmed the findings with a similar comparison.
“One could think of the body of a starfish ... as a disembodied head walking about the sea floor on its lips — the lips having sprouted a fringe of tube feet, co-opted from their original function of sorting food particles, to do the walking,” University of Victoria’s Thurston Lacalli told CBS News. “ ... This is truly a radical transformation of the ancestral bilaterian body plan.”
What are starfish?
Starfish are echinoderms, which means the animal features a five-fold symmetry, unlike most animals, which have a two-fold symmetry, such as humans.
The team studied the genes and found that the genes from “different parts of the starfish ‘arms’ corresponded to different parts of the head,” The Guardian reported.
“The arms of a starfish are not like our own arms, but more like extensions of the head,” Jeff Thompson, a co-author on the study at the University of Southampton, told The Guardian. “To summarize starfish anatomy, I would say it’s a mostly head-like animal with five projections, with a mouth that faces towards the ground and an anus on the opposite side that faces upwards.”
Learning more about the echinoderms can help scientists better understand how the animals survive, as well as learn more about how our own brains might compare, per The Guardian.