Deep-sea discovery uncovers new family of copepods near Greenland

Deep-sea discovery uncovers new family of copepods near Greenland Gaby Clark Scientific Editor Robert Egan Associate Editor An international research team, including Dr. Nancy Mercado Salas from the Leibniz Institute for the Analysis of Biodiversity Change (LIB), has described a new family of copepods (Copepoda). The discovery was made at a depth of more than 2,500 meters in the Irminger Basin, southeast of Greenland, and provides new insights into the evolution of a group of animals that has hitherto been poorly understood. The findings are published in the journal PeerJ. The so-called Monstrilloida are considered one of the most unusual groups of marine copepods. Their larvae live as parasites within other marine organisms, while the adults swim freely in the water and do not feed. Due to their distinctive anatomy—they lack, among other things, the antennae and mouthparts typical of crustaceans—their phylogenetic classification has long been the subject of scientific debate. Since 1852, only a single family had been known within the order Monstrilloida: the Monstrillidae. The newly described family Thalassodoridae therefore represents a significant expansion of the known phylogenetic tree of this group of animals. The description was based on both detailed morphological studies and genetic analyses. The only specimen known to date was collected at a depth of 2,537 meters. It exhibits several characteristics that differ markedly from all previously known Monstrilloids. These include exceptionally long, rear-pointing antennules, as well as previously unknown body structures that could provide new insights into the evolution and lifestyle of these animals. "The discovery of the new family Thalassodoridae shows that the deep sea still harbors life forms previously unknown to science," says Dr. Nancy Mercado Salas of the LIB. "It also opens up new perspectives on the biology, morphology and evolution of this extraordinary group of copepods." The scientific name also reflects the uniqueness of the find: the newly described species, Thalassodoron bathyale, roughly translates as "gift from the deep sea"—a reference to the unexpected discovery of this extraordinary crustacean. Researchers from Germany, Italy and Mexico took part in the study. Publication details Eduardo Suárez-Morales et al, A new family of the order Monstrilloida (Copepoda) from deep waters of the North Atlantic supported by morphological and genetic evidence, PeerJ (2026). DOI: 10.7717/peerj.21176 Journal information: PeerJ