Scientists Uncover Regeneration Clues Hidden in Brittle Sea Star DNA

Brittle stars have long inhabited the ocean floor without drawing much attention. Lacking brains, eyes, or even hearts, they drift through the abyss with five flexible arms and a disk-shaped body, quietly playing their role in recycling nutrients. But beneath their unassuming exterior lies a genetic complexity that has stunned scientists and rewritten what we know about marine life evolution and regeneration.

DNA from over 2,600 brittle stars collected across the globe has revealed that populations in distant locations—like Tasmania and Iceland—share close genetic ties. According to The Guardian, these connections extend across entire oceans, forming what scientists describe as evolutionary “superhighways” beneath the sea.

Photo: Wikimedia Commons / National Marine Sanctuaries, License: Public Domain

Brittle stars lack a brain, eyes, or heart, yet thrive across global oceans.

Larval Drifters Build Global Bridges

Unlike shallow water species restricted by thermal barriers, deep-sea brittle stars exploit the cold, stable environment to disperse their larvae over vast distances. A larva in the deep sea can survive for over a year in a slow, suspended state, floating on sluggish currents until it finds a place to settle.

As The Conversation reports, this long-distance dispersal has created a global patchwork of species more genetically similar than expected.

Some of the most revealing insights have come from museum collections. Genetic sequencing of specimens dating back decades has shown that deep-sea brittle stars share common ancestors, even across hemispheres. These findings challenge the idea that marine species evolve in isolation and suggest that the deep ocean, despite its harsh conditions, is a connected ecosystem.

Photo: Wikimedia Commons / NOAA Office of Ocean Exploration and Research, License: Public Domain

DNA analysis revealed brittle stars from Iceland and Tasmania are closely related.

One Brittle Star, Many Genomes

One species in particular, Amphipholis squamata, has thrown the traditional definition of a species into question. This brooding brittle star carries a genome so vast and variable, it’s difficult to categorize. Through a process called polyploidization—where entire sets of chromosomes are duplicated—these stars carry multiple copies of their genes. This isn’t just a rare occurrence. As Newsweek notes, these duplications allow hybrid lineages to intermingle without breaking reproductive compatibility, resulting in a global population that behaves more like a complex than a species.

Without a dispersal phase in its life cycle, the brooding brittle star’s widespread range may stem from this genetic flexibility, allowing it to adapt and survive in diverse environments. Its reproductive methods remain a mystery, but the evidence suggests a system far more complicated than scientists previously imagined.

Photo: Wikimedia Commons / NPGallery, License: Public Domain

Deep-sea environments act as superhighways for brittle star migration.

Masters of Regeneration

Equally impressive is the brittle star’s ability to regrow lost limbs. A new chromosome-scale genome assembly for Amphiura filiformis, published in Nature Ecology & Evolution, sheds light on how this is possible. The species exhibits one of the most rearranged genomes in its phylum, including restructured Hox and ParaHox gene clusters—sections of DNA that guide body plan development.

The regeneration process unfolds in three stages: wound healing, cell proliferation, and tissue differentiation. Each phase triggers a unique wave of gene expression. Genes tied to immune response and stemness are activated early, while others govern the regrowth of nerves, muscles, and patterned structures.

Remarkably, many of these genes are shared with vertebrates, including those found in axolotls and crustaceans, suggesting deep evolutionary conservation.

Photo: Wikimedia Commons / NOAA/MBARI, License: Public Domain

Some brittle star species show more genetic variation than entire genera.

Implications Stretch Beyond the Sea

The genetic revelations go far beyond brittle stars. The research presents them as a crucial link in understanding how regeneration evolved in animals. Brittle stars may serve as a bridge between vertebrates and other invertebrate model organisms, allowing scientists to explore shared biological pathways.

These spiny deep-sea dwellers are not just biological curiosities. They offer a new lens through which to understand resilience, adaptation, and the hidden connections threading through Earth's oceans. With rapid environmental change on the horizon, that lens has never been more vital.