The discovery emerged from a research effort led by scientists at Sun Yat-sen University (SYSU) and the Southern Marine Science and Engineering Guangdong Laboratory in Zhuhai. Using modern deep-sea diving vehicles, including human-occupied vehicles and remotely operated vehicles, the team filmed deep-sea organisms in their natural habitat across three areas of the northern South China Sea. Among the animals they documented were three species of peristediid fishes, commonly called armored searobins: Scalicus engyceros, Paraheminodus murrayi and Peristedion liorhynchus. The footage captured not just still portraits of these animals but extended records of their benthic behaviors, allowing the researchers to describe, for the first time, how the fishes move and forage while alive on the seafloor.

Han Tian, the paper’s primary author and a doctoral researcher in the School of Marine Sciences at Sun Yat-sen University, described the finding as a paradigm-shifting revelation. S. engyceros belongs to a group of fishes characterized by highly specialized free pectoral-fin rays, finger-like appendages that extend from the pectoral fins and make contact with the seafloor. Scientists have long suspected that searobins use these rays to walk, but until now the behavior had not been directly confirmed with in situ footage. The species has even attracted popular attention for its appearance, which combines features of fish and shrimp so strikingly that U.S. local media have dubbed it a “fish-prawn hybrid.”

The walking itself proved more versatile than anyone anticipated. Searobins were first described by the zoologist Albert Günther in 1872, yet in the more than 150 years since, no one had predicted that these fishes could walk both sideways and backward. Locomotion in reverse has never been observed in other fishes, making the armored searobin’s gait a genuine first for the field. The finding illustrates how much basic behavioral information remains locked in the deep sea, inaccessible until organisms can be observed alive in their own environment rather than studied from preserved specimens hauled up in trawls.

The searobin’s body plan reveals a suite of adaptations that appear tailored to life on soft seafloor sediment. Beyond the walking rays, the fish sports outward-extending barbels that Tian compared to a farmer’s rake. While the structure may look awkward for getting around, it serves a foraging function: the barbels allow the searobin to sense and probe potential prey buried in the seafloor sediment, and even to dig into the surface sediment itself in search of food. Meanwhile, the animal’s main pectoral fins have evolved into flat, round plates, which appear to improve balance both during walking and while swimming. When threatened, the fish can deploy its shrimp-like fin rays and tail to make explosive, jerky leaps reminiscent of a startled shrimp, a rapid escape behavior that complements its slower, deliberate walking.

The filmed observations also yielded unexpected insights into the searobin’s sensory world. The fish’s large eyes could not resolve the approaching vehicle itself, indicating that its visual acuity is limited at close range. Yet when the vehicle’s light beam swept near, the animal rolled its eyes toward the light. This response suggests that the searobin’s eyes have retained some sensitivity to light, which, according to the researchers, may reflect a light history during the species’ life cycles. Many deep-sea fishes begin life in shallower, sunlit waters before descending to the abyss, and the eye-rolling behavior hints at vestiges of that developmental or evolutionary past, though the team presents the observation as a suggestion rather than a settled conclusion.

The fact that three different armored searobin species were observed at different locations in the South China Sea raised another question for the team. The distribution of these similar fishes across separate sites suggests, in the researchers’ view, the hypothesis that local specialization forces may be at work, shaping each population’s adaptations to its particular patch of seafloor. Testing that hypothesis will require further observation and comparison, but it points toward a research program that treats deep-sea fishes not as static curiosities but as dynamically evolving lineages responding to the distinct conditions of their habitats.

The methodological significance of the study lies in its approach. Classified as an observational study, the work rests on in situ filming rather than laboratory experimentation or dissection. Advances in deep-sea vehicle technology, including human-occupied vehicles and remotely operated vehicles, have transformed what is possible for deep-sea biology. Where earlier generations of scientists had to infer behavior from the anatomy of dead specimens, today’s researchers can watch living animals interacting with their environment. Tian emphasized that modern diving vehicles allow not only the discovery of new species but also add a new in situ, functional dimension to the study of species that were previously known only from preserved morphology. Observing deep-sea animals alive in their surroundings, the team argues, provides direct insight into adaptation and evolution that museum specimens alone cannot supply.

The broader context makes the finding all the more compelling. The deep ocean is one of the most inhospitable places on Earth, characterized by crushing pressure, perpetual darkness and scarce food, yet many species have managed to survive there, often evolving specialized body structures and behaviors in the process. Armored searobins represent one such evolutionary experiment: a lineage that has repurposed its pectoral fins into a hybrid toolkit serving walking, balance, foraging and escape. The combination of rake-like barbels for probing sediment, plate-like fins for stability, free rays for stepping across the bottom and shrimp-style leaps for emergency escapes suggests a tightly integrated adaptive complex rather than a single isolated trait.

Looking forward, the team intends to push beyond this initial documentation. Tian said the researchers aim to explore the co-evolution of the fish’s unique rake-shaped appendages, its walking locomotion and its deep-sea foraging strategies, with the goal of establishing a new framework for understanding benthic fish adaptive evolution. Such a framework could reshape scientific perceptions of deep-sea biodiversity and illuminate how extreme marine environments drive the emergence of biological structures and behaviors seen nowhere else in the world’s aquatic ecosystems. In the team’s view, these walking fish harbor far more novel behavioral and evolutionary adaptations than previously assumed.

The research was a collaborative effort. Alongside Tian, contributors included Wei Xie, Mingting Li and Kedong Yin, affiliated with the School of Marine Sciences and the Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering at Sun Yat-sen University, and with the Southern Marine Science and Engineering Guangdong Laboratory in Zhuhai, China. The paper, titled “Walking Fish,” carries the DOI 10.34133/olar.0172, and the authors reported no conflicts of interest. As with any observational study, the findings describe what the cameras captured in a limited number of encounters and locations; the mechanisms underlying the backward gait, the developmental basis of the fish’s light sensitivity and the role of local specialization remain open questions for future work. Still, the footage marks a milestone: after a century and a half in the scientific record, the armored searobin has finally been seen doing what its anatomy always hinted at, walking, in every direction, across the dark floor of the South China Sea.

The coral was encountered during research expeditions to seamounts near Isla del Coco and along Costa Rica’s Pacific margin in 2019 and 2023. Scientists collected specimens with the remotely operated vehicle SuBastian, deployed from the research vessels Falkor and Falkor (too) by the Schmidt Ocean Institute. Some colonies exceeded a metre in height, forming what researchers described as expansive octocoral gardens. Their vivid yellow colour and branching architecture made them visually distinctive, but their true significance became clear only after detailed morphological and genetic investigations.

The colonies occupied rocky outcrops that were almost entirely blanketed by brittle stars. Thousands of the small, many-armed echinoderms created a shimmering seafloor, while the coral branches extended above them like miniature trees. This unusual setting inspired both parts of the scientific name. Laurinque is derived from “Laurinquë,” a Quenya word meaning “golden tree” in the Elvish language created by J.R.R. Tolkien. The species name elenya means “stellar” or “of the stars,” referring to the brittle-star fields surrounding the coral. Together, the name evokes a golden forest rising through a star-filled deep-sea landscape.

At first, the researchers expected the coral to belong to an already recognised group. Octocorals are colonial animals in the class Anthozoa, a major branch of the cnidarians that also includes sea anemones and stony corals. Unlike reef-building stony corals, octocorals typically possess eight-part symmetry in their polyps and often develop flexible, branching colonies. Their classification relies on a combination of features, including colony form, skeletal structures, polyp anatomy and DNA sequences. In the case of L. elenya, however, those lines of evidence repeatedly produced conflicting results.

The research team initially sequenced three genes commonly used to reconstruct relationships among corals. Each gene placed the species near a different, unrelated family. Such disagreement can occur when genetic markers have evolved at different rates or when ancient lineages diverged rapidly, leaving too little information in individual genes to resolve their relationships. For this coral, the conflict was unusually pronounced. Its external appearance also failed to match known genera convincingly, suggesting that the animal might represent a deeply isolated evolutionary branch rather than an unusual member of a familiar group.

To resolve the mystery, the scientists used phylogenomics, a method that compares hundreds of genes simultaneously instead of relying on a small number of genetic markers. By examining a much broader portion of the genome, researchers can identify evolutionary signals that may be obscured or distorted in individual genes. The analysis showed that Laurinque elenya is most closely related to the octocoral family Eunicellidae, but it is separated from that group by substantial genetic and anatomical differences. The evidence indicated that the coral could not be placed within any existing family.

The team therefore established Laurinqueidae as a new family, along with the new genus Laurinque and the species Laurinque elenya. Creating a new family is a significant taxonomic decision, especially among animals that have been studied for centuries. It means the organism is not simply a new species within a known branch, but represents an evolutionary lineage with characteristics distinct enough to deserve its own major division. The finding also demonstrates how DNA-based research can reveal relationships that are not apparent from outward appearance alone.

Lead researcher Dr Odalisca Breedy of the Universidad de Costa Rica first saw the coral gardens during the 2019 expedition. The landscape’s beauty initially inspired the eventual Elvish name, but Breedy said preliminary morphological work soon suggested that the coral did not correspond to any recognised genus or family. Additional samples collected in 2023 enabled a more comprehensive investigation, supported by molecular analyses conducted with collaborators Cathy McFadden, Catalina Murillo and Andrea Quattrini. Together, the anatomical and genomic evidence established the coral’s unique taxonomic position.

The discovery is also a reminder that deep-sea ecosystems remain poorly documented. Seamounts create isolated underwater elevations where currents, hard surfaces and food delivery can support specialised communities, including corals, sponges, brittle stars and other suspension-feeding animals. Coral gardens provide three-dimensional habitat in otherwise open environments, offering shelter and attachment surfaces for many species. Because these communities grow slowly and may be damaged by fishing gear, mining activity or other disturbances, they are considered vulnerable marine ecosystems. Finding a previously unknown coral family in a relatively accessible part of the eastern Pacific suggests that many more evolutionary lineages may still await discovery in the planet’s deep waters.

Subject of Research: Discovery and phylogenomic classification of a new deep-sea octocoral family, genus and species from Costa Rican seamounts.

Article Title: A coral among stars: A new octocoral family (Anthozoa, Octocorallia, Malacalcyonacea) from seamounts in the tropical eastern Pacific

News Publication Date: 30-Jun-2026

Web References: ZooKeys: https://zookeys.pensoft.net/article/191899/ ; Schmidt Ocean Institute: https://schmidtocean.org/ ; Universidad de Costa Rica: https://www.ucr.ac.cr/

References: DOI: 10.3897/zookeys.1283.191899

Image Credits: ROV SuBastian

Keywords: deep-sea coral, octocoral, Laurinque elenya, Laurinqueidae, Costa Rica, seamounts, phylogenomics, marine biodiversity, brittle stars, deep ocean exploration