Imagine an order of animals named after a species... that doesn't belong to it.

In one of the most ironic developments in fish taxonomy, the Japanese sea bass (Suzuki) has been reclassified out of the Perciformes, an order that was named "Suzuki-moku" (スズキ目, literally "Sea Bass Order") in Japanese specifically because it included this fish. Thanks to major advances in molecular phylogenetics, scientists are now rewriting the entire classification of fish based on DNA evidence rather than appearance.

The Rise and Fall of the World's Largest Fish Order

The Perciformes was once the undisputed heavyweight champion of vertebrate orders. With some 10,000 species across roughly 160 families, around 40 percent of all bony fishes, it was the largest order in the entire animal kingdom, taking in everything from tuna and mackerel to sea bream and groupers.

In Japan, this massive group was called "Suzuki-moku" (スズキ目), named after the sea bass (Lateolabrax japonicus), one of the most commercially important and culturally significant fish in Japanese cuisine and recreational fishing. Nearly every "typical-looking" fish belonged to this order.

The DNA Revolution

Everything changed with the advent of molecular phylogenetics, a technique that compares DNA sequences to determine evolutionary relationships between species.

Traditional taxonomy relied on morphological features, body shape, fin placement, scale patterns, and skeletal structure. But this approach had a fatal flaw: convergent evolution. Unrelated species living in similar environments often evolve similar physical features, making them appear related when they're not.

DNA analysis cuts through this illusion. By comparing genetic sequences, scientists can trace the actual evolutionary history of organisms, revealing which species share common ancestors and which merely look alike due to environmental pressures.

The Great Perciformes Breakup

There was always something suspicious about Perciformes. It was so large and so diverse that taxonomists often called it a taxonomic wastebasket, a catch-all for any perch-like fish that couldn't be placed anywhere else.

When molecular phylogenetic analysis was applied to Perciformes, the results were staggering. The order was revealed to be polyphyletic, meaning its members didn't share a single common ancestor exclusive to the group. In other words, Perciformes was an artificial grouping of unrelated fish that just happened to look similar.

The great dismantling began. Former Perciformes members have been redistributed into numerous new orders:

  • Centrarchiformes (sunfishes, including species like the opaleye)
  • Perciformes (now much smaller, containing true perches)
  • Labriformes (wrasses)
  • Gobiiformes (gobies)
  • Carangiformes (jacks and mackerels)
  • Scombriformes (tunas)
  • Acropomatiformes (lanternbellies... and sea bass!)

The Ironic Reclassification of Sea Bass

Perhaps the most surprising finding was that the Japanese sea bass itself doesn't belong to Perciformes.

DNA analysis revealed that Lateolabrax japonicus is more closely related to small, deep-sea fish called lanternbellies (family Acropomatidae) than to the other fish in its former order. Sea bass has been reclassified into Acropomatiformes, an order defined entirely by molecular evidence rather than visible characteristics.

Lanternbellies top out at around 20 centimeters and live at depths of roughly 100 to 500 meters, carrying light organs on their bellies that glow thanks to symbiotic bacteria. They look nothing like a sea bass approaching a meter in length. Yet genetically, they are relatives.

This is the power, and sometimes the counterintuitive nature, of molecular phylogenetics. Evolution doesn't always leave visible traces, and appearances can be deeply deceiving.

The Name Problem

This reclassification creates an awkward situation for Japanese terminology. The order Perciformes is called "スズキ目" (Suzuki-moku, "Sea Bass Order") in Japanese, but now contains no sea bass.

The scientific name Perciformes comes from Perca, the freshwater perch genus, and simply means "perch-shaped fishes"; it never depended on including the Japanese sea bass at all. A new Japanese name, "ペルカ目" (Peruka-moku), has been proposed on those grounds, and "パーチ目" (Perch Order) has been floated too. Taxonomic renaming tends to be slow and conservative, though, so the ironic old name may hang around for a while.

What This Means for Science

The Perciformes restructuring exemplifies how modern technology is revolutionizing our understanding of life on Earth:

1. Environmental DNA (eDNA) Research Scientists can now identify which fish species inhabit an area simply by collecting water samples and analyzing the DNA fragments left behind by organisms. This technique has discovered species in locations where they'd never been documented before.

2. Rewriting Evolutionary History Molecular clocks, which estimate when species diverged based on genetic differences, are helping scientists understand when and how fish diversified. Many fish orders appear to have exploded in diversity after the mass extinction event 66 million years ago.

3. Conservation Applications Accurate taxonomy is crucial for conservation. Understanding which species are truly related helps scientists identify biodiversity hotspots and prioritize protection efforts.

4. Fisheries Management Knowing the true relationships between fish species can improve our understanding of their ecology, helping develop more effective and sustainable fishing practices.

Does your country have its own version of this, a species that gave a group its name and then turned out not to belong in it?

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