Sea anemones share a biological trick with humans

Sea anemones look like simple, radial animals. Yet their bodies hide a front-to-back plan that mirrors the layout seen in animals with heads and tails.

A new study shows that the cells of these soft-bodied creatures read chemical hints to decide which side becomes “back” and which becomes “belly.”

Link between sea anemones and humans

Scientists at the University of Vienna found that sea anemones rely on a process called BMP shuttling to organize their developing bodies.

This same biological mechanism is responsible for shaping the body axes in many familiar animals from insects to vertebrates, including humans.

The discovery pushes the origin of this cellular traffic system back more than 600 million years, suggesting it was already present in a common ancestor of nearly all modern animals.

This finding not only highlights the deep evolutionary connection between simple and complex organisms but also opens up new ways of thinking about how body plans are genetically encoded and inherited across generations.

The research suggests that what we see in modern animals may be built upon a remarkably ancient and shared developmental toolkit.

Signals that guide developing cells

Bone Morphogenetic Proteins (BMPs) are signals that guide developing cells. A partner molecule, Chordin, can both block these signals and move them to new spots.

The moving act – shuttling – creates precise highs and lows of BMP activity. Early cells read these highs and lows like a map, turning into skin, nerve tissue, or other organs.

The researchers worked with Nematostella vectensis, a small sea anemone commonly used in laboratory studies.

Body development in sea anemones

To understand how Chordin functions, they first blocked its production in developing sea anemone embryos. As a result, BMP activity came to a halt, and the second body axis failed to form.

To test Chordin’s role further, the team introduced two different forms of the molecule: one that was fixed in place and could not move, and another that was free to drift through the embryo.

Only the free-moving version was able to restore BMP signaling on the opposite side of the embryo. This result showed that Chordin does more than just block BMPs – it actively shuttles them across the developing body.

Why this matters for evolution

David Mörsdorf is the first author of the study and a postdoctoral researcher in the Department of Neurosciences and Developmental Biology at the University of Vienna.

“Not all Bilateria use Chordin-mediated BMP shuttling, for example, frogs do, but fish don’t, however, shuttling seems to pop up over and over again in very distantly related animals making it a good candidate for an ancestral patterning mechanism,” said Mörsdorf.

“The fact that not only bilaterians but also sea anemones use shuttling to shape their body axes, tells us that this mechanism is incredibly ancient. It opens up exciting possibilities for rethinking how body plans evolved in early animals.”

Grigory Genikhovich, senior author of the study, added that experts might never be able to exclude the possibility that bilaterians and bilaterally symmetric cnidarians evolved their bilateral body plans independently.

“However, if the last common ancestor of Cnidaria and Bilateria was a bilaterally symmetric animal, chances are that it used Chordin to shuttle BMPs to make its back-to-belly axis. Our new study showed that,” said Genikhovich.

Future clues in simpler creatures

The work suggests that a single, ancient blueprint guided the rise of complex body shapes across many animal lineages. Future studies may search for BMP shuttling in even older or simpler groups, testing just how deep this shared strategy runs in the history of life.

Understanding BMP shuttling in sea anemones doesn’t just tell us about the past – it could also shape the future.

Because BMP signals are important in how all kinds of animals develop their bodies, including humans, this research could help scientists better understand birth defects, tissue growth, and even how to guide stem cells into becoming the right types of tissue.

By studying these simple creatures, researchers may unlock clues about how to repair or regrow parts of the human body. And by tracing the history of how body plans evolved, scientists can more confidently predict which genes or molecules are truly essential across all animal life.

The full study was published in the journal Science Advances.

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