Scientists Discover New Species of Ancient Marine Creature Hiding in Plain Sight Off South Korea
A chiton — a type of marine mollusk whose lineage stretches back roughly 500 million years — has been identified as a brand-new species after being misclassified for years, thanks to a routine DNA analysis that revealed it was genetically distinct from the species it resembled.
The creature, now named Acanthochitona feroxa, had long been lumped in as a subspecies of another known chiton, Acanthochitona defilippii. The two look so similar to the naked eye that no one had questioned the classification — until biologists examined its mitochondrial genome.
Biologists Hyang Kim and Ui Wook Hang of Kyungpook National University in South Korea made the discovery while analyzing the mitochondrial genomes of several Acanthochitona species. A mitochondrial genome is the set of genetic instructions found inside mitochondria, tiny structures within cells that produce energy. Scientists use mitochondrial DNA to compare species because it evolves at a relatively consistent rate, making it useful for measuring how closely related two organisms are.
Kim and Hang sequenced the mitochondrial genome of what turned out to be the new species and compared it to four other existing Acanthochitona species. Their findings were published in Marine Life Science & Technology.
“The findings of this study can provide foundational data for future molecular investigations into Acanthochitona, offering insights into the complete mitochondrial genomes of these five species and their phylogenetic relationships,” Kim and Hang said in the study.
What Are Chitons?
Chitons belong to the class Polyplacophora, a group of marine mollusks — distant relatives of snails, clams, and octopuses — distinguished by a series of overlapping shell plates running down their backs. They are estimated to have evolved around 500 million years ago, predating the age of dinosaurs by roughly 265 million years.
More than 1,300 chiton species are known today, with approximately 940 known species having changed little over the last 300 million years. That consistency has earned them a reputation as “living fossils” — organisms that have survived vast stretches of geological time with remarkably little physical change.
Physical Differences Required Serious Magnification
Once researchers began looking more carefully, differences between feroxa and defilippii started to emerge — but only under a scanning electron microscope.
Researchers observed differences in dorsal spicules, tiny thorn-like projections on the animal’s back. In the newly identified species, these spicules were rounded rather than pointed. Differences were also found in the radula — a tongue-like feeding structure common to mollusks — and in the shell plates themselves.
These physical clues, combined with the molecular genetic analysis, confirmed Acanthochitona feroxa as a distinct species. “These molecular techniques have been proven potent in uncovering cryptic species within groups that exhibit morphological similarities,” the researchers said.
“Cryptic species” refers to organisms that look virtually identical to another species on the outside but are genetically distinct enough to be classified separately. The concept has become increasingly important in biology as genetic sequencing tools have grown more powerful, revealing more diversity than the eye alone can detect.
A Name Rooted in Latin
The species was identified from specimens collected off the southern and western coasts of South Korea. Its name, feroxa, derives from the Latin “ferox,” meaning “fierce” or “bristling,” a reference to the tufts along the edges of its flattened oval shell.
The broader group Polyplacophora began diversifying approximately 378 million years ago during the Devonian Period. The genus Acanthochitona developed about 92 million years ago during the Late Cretaceous, when dinosaurs still roamed the Earth.
Without mitochondrial genome sequencing, Acanthochitona feroxa might have remained indefinitely grouped with its look-alike relative. The discovery suggests there may be other cryptic species quietly waiting to be distinguished from their near-identical neighbors.
Production of this article included the use of AI. It was reviewed and edited by a team of content specialists.
