In the shadowy depths of Bermuda’s intricate limestone cave network, scientists have unveiled a remarkable discovery that enriches our understanding of subterranean marine biodiversity. An international team of researchers from the University of Cambridge, the Bermuda Institute of Ocean Sciences, and the Senckenberg am Meer German Centre for Marine Biodiversity Research have identified a previously unknown species of copepod, a tiny crustacean that plays a fundamental role in aquatic ecosystems worldwide. This newly described species, Tetragoniceps bermudensis, adds a significant chapter to the story of life beneath the island’s surface, highlighting the extraordinary and often overlooked biodiversity harbored within anchialine caves.
Copepods are microscopic crustaceans that inhabit a vast array of aquatic environments, from freshwater ponds to the vast expanses of the open ocean. Despite their small size, they constitute one of the most abundant groups of animals on Earth and serve as critical components of marine food webs, transferring energy from primary producers to fish and other higher trophic levels. However, the immense diversity within this group remains incompletely cataloged, especially in secluded and challenging habitats such as subterranean and anchialine cave systems — semi-enclosed coastal water bodies with connections to both freshwater and marine ecosystems.
The newly identified species, Tetragoniceps bermudensis, was originally collected in 2016 during a series of daring explorations by Sahar Khodami, Pedro Martinez Arbizu, and Leocadio Blanco-Bercial. Venturing into Roadside Cave, one of Bermuda’s lesser-known anchialine caves, through narrow passages embedded within ancient carbonate bedrock, they retrieved an individual female copepod carrying eggs. It was only after meticulous morphological and genetic analyses conducted in 2024 by lead author Giovanni Mussini and colleagues that the specimen was confirmed as a novel species, unique to this isolated ecosystem. The designation “bermudensis” pays homage to its geographic origin, linking this organism’s identity to the island’s distinctive subterranean environment.
This discovery is noteworthy as T. bermudensis represents the first species of the genus Tetragoniceps to be found in Bermuda and is the first ever cave-dwelling species within this genus worldwide. The genus itself belongs to the family Tetragonicipitidae, a group of copepods typically found in marine planktonic or benthic habitats. Prior to this finding, only one other cave-adapted species has been described in this family, underscoring the rarity and specialization of such organisms in subterranean ecosystems. The evolutionary lineage to which T. bermudensis belongs is likely ancient, with the species being a relict that has persisted through geological time in seclusion, relatively undisturbed by competitors or predators.
What makes anchialine caves like Roadside Cave particularly fascinating is their unique environmental conditions — they contain stratified layers of water, where freshwater overlies saline marine water, creating chemically distinct habitats that support specialized faunal communities. This stratification, combined with limited light penetration and nutrient input, fosters the evolution of endemic species that are finely tuned to these extreme environments. The discovery of T. bermudensis within this context suggests that Bermuda’s cave systems continue to serve as refugia for ancient biological lineages, providing insight into evolutionary processes in isolated and stable habitats.
Despite identifying only a single egg-carrying female specimen, researchers posit that T. bermudensis is likely a highly localized endemic species. The limited distribution and elusive nature of cave-dwelling fauna complicate population assessments, but this rarity underscores the vulnerability of such species to environmental change and anthropogenic disturbance. The narrow ecological niche occupied by T. bermudensis suggests that its habitat requirements are specific and finely balanced, where even minor alterations could lead to population declines or extirpation.
This sensitivity is particularly concerning given the anthropogenic pressures facing Bermuda’s delicate cave ecosystems. Unregulated urban development, vandalism, illegal dumping, and sediment disturbance from unauthorized human and animal access threaten the physical integrity and water quality of anchialine habitats. Pollutants introduced into these systems can disrupt the intricate chemical stratification and pose direct toxicity risks to endemic fauna. The researchers emphasize the urgent need for formal protection measures, robust enforcement of existing environmental regulations, and heightened public awareness to safeguard these subterranean biodiversity hotspots.
The discovery of T. bermudensis also raises broader scientific and conservation questions about how many other cryptic species may inhabit Bermuda’s caves and similar anchialine environments globally. These systems are notoriously underexplored due to their inaccessibility and the technical challenges of sampling in such environments. Yet, they likely harbor a wealth of undocumented species, many of which may represent early-diverging branches of evolutionary lineages, offering unique perspectives on adaptation, speciation, and the resilience of life in extreme habitats.
In addition to morphological characterization, the research incorporates an updated taxonomic key for the genus Tetragoniceps, facilitating future identification and differentiation of species within this group. This tool will aid taxonomists and ecologists in recognizing subtle morphological traits critical for species delimitation, particularly when dealing with morphologically similar copepods from diverse environments.
Moreover, the collaborative international nature of the research reflects the interdisciplinary efforts required in contemporary biodiversity discovery. It combines expertise in taxonomy, systematics, molecular biology, and cave ecology, supported by advanced microscopy techniques, including confocal laser scanning microscopy, which provides high-resolution imaging of the minute anatomical structures of copepods. Such integrative approaches are essential for unravelling the complexity of life in fragile and understudied biomes.
This singular discovery stands as a testament to the rich, often hidden biodiversity that inhabits our planet’s less accessible corners and underscores the importance of continued exploration and monitoring. As human activities increasingly encroach upon natural habitats, documenting and protecting such species becomes imperative for maintaining ecological balance and preserving evolutionary heritage. Tetragoniceps bermudensis is not just a new addition to the catalog of life but a symbol of the secret wonders lying beneath the surface — waiting to be revealed.
The unveiling of this tiny crustacean from Bermuda’s Roadside Cave ultimately propels a call to action within the scientific community and conservationists alike. It highlights the importance of preserving subterranean habitats, integrating them into conservation frameworks, and fostering collaboration across disciplines and borders. In doing so, we deepen our understanding of biodiversity’s breadth and resilience while safeguarding the biological treasures embedded in the world’s hidden aquatic realms.
Subject of Research: Discovery of a new cave-dwelling copepod species in Bermuda’s anchialine cave system
Article Title: A new species of Tetragoniceps Brady, 1880 (Copepoda, Harpacticoida, Tetragonicipitidae) from an anchialine cave in Bermuda, with an updated key to the species of the genus
News Publication Date: 20-May-2025
Web References: http://dx.doi.org/10.3897/zookeys.1239.144436
References: Mussini G, Niimi YJ, Khodami S, Kihara TC, Martinez Arbizu P, Blanco-Bercial L (2025) A new species of Tetragoniceps Brady, 1880 (Copepoda, Harpacticoida, Tetragonicipitidae) from an anchialine cave in Bermuda, with an updated key to the species of the genus. ZooKeys 1239: 1-19.
Image Credits: Mussini et al.
