Starfish are heads without bodies. They might be cute, but this is creepy

Some think starfish are cute, and some say they are scary. To some, these star-shaped echinoderms which belong to the class Asteroidea, are creepy. Now, the level of creepiness may increase further as this new study about this sea creature says that the entire body of a starfish is essentially one big head, and they don't have the architecture for an actual body.

Known facts about starfish say that they can regenerate their arms, they have no brain or blood, they wear tough, leathery skin, and they have eyes.

A team led by biologists Laurent Formery and Chris Lowe of Stanford University said that starfish are just mobile heads that manage the ability to move from one place to another, basically acrawl.

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Laurent Formery, lead author and postdoc in the labs of Christopher Lowe at the Stanford School of Humanities and Sciences and Daniel S Rokhsar at the University of California, Berkeley, said: "The answer is much more complicated than we expected. It is just weird, and most likely the evolution of the group was even more complicated than this."

Not just starfish, sea urchins, sand dollars, sea cucumbers also echinoderms. When we look at them in oceans or fish aquariums, they may come across as normal as oceans are filled with such unusual creatures, but starfish are very different and keep intriguing scientists.

The paper, titled "Molecular evidence of anteroposterior patterning in adult echinoderms", was published on Nov 1 in Nature.

As quoted by Study Finds, Lowe, also a researcher at Hopkins Marine Station, said that "this has been a zoological mystery for centuries. How can you go from a bilateral body plan to a pentaradial plan, and how can you compare any part of the starfish to our own body plan?"

To find more details, a new Stanford study used genetic and molecular tools to map out the body regions of starfish.

They created a 3D atlas of their gene expression so that they get answers about the sea stars.

The researchers found that the "head" of a starfish is not in any one place.In fact, the headlike regions are scattered everywhere, with some in the centre, and some in the centre of each limb of its body.

As quoted by Science Alert, biologist Jeff Thompson of the University of Southampton in the UK, said: "How the different body parts of the echinoderms relate to those we see in other animal groups has been a mystery to scientists for as long as we've been studying them."

"In their bilateral relatives, the body is divided into a head, trunk, and tail. But just looking at a starfish, it's impossible to see how these sections relate to the bodies of bilateral animals," Thompson added.

The study noted: "We investigated the expression of a suite of conserved transcription factors with well-established roles in the establishment of anteroposterior polarity in deuterostomes and other bilaterians using RNA tomography and in situ hybridization in the sea star Patiria miniata."

It added, "The relative spatial expression of these markers in P. miniata ambulacral ectoderm shows similarity with other deuterostomes, with the midline of each ray representing the most anterior territory and the most lateral parts exhibiting a more posterior identity."