When a cube of seafloor mud is brought onto a ship’s deck, run through a sieve, and found to contain something no one has ever seen before, it is a strange moment in deep-sea research. It’s not particularly dramatic. It’s silent. It was a spindly, pale creature sitting in a tray of sediment, completely unaffected by the fact that it had just completely disrupted someone’s conception of life on Earth. The scientific community is only now starting to consider the implications of that moment, which has been occurring more frequently lately.
Numerous previously unidentified crustacean species have been discovered over the past few years by expeditions that target deep waters off U.S. coastlines and throughout the wider Pacific. Recent tallies have surpassed fifty new amphipod discoveries across various research programs. The six-million-square-kilometer Clarion-Clipperton Zone, which lies between Hawaii and Mexico on the Pacific seafloor, is one of the most species-rich—and least understood—environments that scientists have ever come across. Not too long ago, only thirteen amphipod species were officially recognized from that area. According to genetic sampling, the true number may be more than 200.
This leads to a classification issue that is more than just a small administrative hassle. The system used by scientists to classify and identify living things, known as taxonomy, is based on centuries of accumulated consensus. Based on morphological similarities, evolutionary relationships, and shared traits, new species are assigned to preexisting families and genera. However, that system begins to strain at the seams when dozens of animals arrive at once, many of which are so unlike anything previously described that it is unclear who their closest relatives are. In a single journal issue, researchers studying the CCZ amphipods described twenty-four new species from ten different amphipod families. This rate of discovery exceeds the number of qualified taxonomists who can handle them.
Deep-sea scientist Dr. Eva Stewart, who helped name a number of the new species, has been open about the backlog. She has pointed out that about 90% of the estimated 5,600 species in the CCZ are still officially undescribed, not because scientists haven’t found them, but rather because the process of processing, comparing, and formally classifying new organisms proceeds much more slowly than the rate of discovery. The specimens are waiting. In a way, science is ahead of itself.
The role that genetics is playing in reshaping what scientists believed they already knew is what complicates this particular wave of discoveries. Under DNA analysis, a number of amphipod species that were thought to be single, well-understood organisms have turned out to be multiple distinct species that merely resemble one another; this phenomenon is known as cryptic speciation. One amphipod, Eurythenes gryllus, was first recorded as a recognized species when it was recovered from the Atacama Trench in 2009. Ten years later, using both morphological analysis and DNA barcoding, scientists discovered it was something completely different: a new species, now known as Eurythenes atacamensis, that is endemic to one of the planet’s deepest regions and is over eight centimeters long. Some entries in current classification databases may themselves be composites, placeholders that contain multitudes, which is an unsettling but useful implication.
The fact that mining interests have accelerated the science makes it difficult to ignore how much of this is occurring. The minerals found in the metallic nodules that cover the CCZ floor are essential for wind turbines and solar panels, making the area more commercially appealing than it was a generation ago. Funding for quick biodiversity surveys has been pushed by this commercial pressure, which has resulted in data being produced more quickly than the taxonomic system can process. The extractive economy unintentionally funding the documentation of life that it may ultimately destroy is somewhat ironic.
More than thirty new midwater species, including crustaceans, jellyfish, and organisms that moved in ways that scientists didn’t anticipate given their body structures, were recently confirmed in the first two weeks of a single expedition off the coast of Brazil on the Schmidt Ocean Institute’s research vessel. Scientists are able to describe new species without even gathering physical specimens thanks to sophisticated imaging tools, such as lasers that scan animals in three dimensions without touching them. That is a significant enough methodological change that it might necessitate formal changes to the way classification operates.
The ocean appears to be resistant to summarization the deeper you delve. Researchers have discovered that amphipods in the hadal zone—anywhere below 6,000 meters—have developed biochemical and physical adaptations that are so unique to their surroundings that it occasionally feels awkward to include them in the current genus structures. The system is being asked to support creatures that were not taken into account during its design. There is no problem with taxonomy. However, it is undoubtedly under pressure, and fifty new crustaceans from deep waters in the United States are just one reason.
