The world of life in the deep sea has hardly been researched yet. Now marine biologists have discovered a previously unknown family of copepods in the North Atlantic. The specimen of this new group of cancers discovered at a depth of 2,500 meters differs significantly from all known relatives. The find shows how much hidden life still exists in the deep sea and helps to better understand the development of marine animals.
There is a world hidden in the deep sea that is still largely hidden from us humans. Numerous animal species live there that are currently unknown to science. Thanks to diving robots and new methods of deep-sea research, researchers are only gradually beginning to understand the diversity of deep-sea inhabitants.
A special kind of copepod
An international research team led by Eduardo Suárez-Morales from El Colegio de la Frontera Sur in Mexico has now shed a little light into the darkness. For their study, they examined samples from the sea floor that were taken at a depth of 2,537 meters in the North Atlantic, southeast of Greenland. The team discovered a small copepod that did not fit into any previously known species, genus or family. Copepods are small crustaceans that are widespread in seas and freshwaters.
The species, which has now been newly discovered in the deep sea, belongs to the so-called Monstrilloida. These copepods are considered particularly unusual: their larvae live parasitically in other marine organisms. The adult animals, on the other hand, swim freely in the water but no longer eat. Their body structure is also striking because, among other things, they lack the antennae and mouthparts typical of crabs. Their placement in the crustacean family tree has therefore long been the subject of scientific discussion. Until now, only one family was known within the order Monstrilloida: the Monstrillidae, which was described in 1852.
Unusual features and a whole new family
To find out more about their discovery, Suárez-Morales and his team combined anatomical studies with comparative genetic analyses. This showed that the copepod found in the deep sea is clearly different from all previously known monstrilloids. Among other things, it has exceptionally long, backward-facing antennae as well as other body structures previously unknown in this group of cancer. These features could provide new clues about how these unusual crustaceans evolved and how they live in the deep sea. Because so far little is known about the biology of the Monstrilloida.
Due to the clear differences from all other copepods known to date, the researchers have not only assigned their deep-sea find to a new species and genus, but to its own family, the Thalassodoridae. The new species was given the name Thalassodoron bathyale – this means “gift from the deep sea”. “The discovery of the new family Thalassodoridae shows that the deep sea of the oceans still harbors life forms that are previously unknown to science,” says senior author Nancy Mercado Salas from the Leibniz Institute for the Analysis of Biodiversity Change (LIB). “It also gives us new perspectives on the biology, morphology and evolution of this extraordinary group of copepods.”
Source: Leibniz Institute for the Analysis of Biodiversity Change (LIB); Specialist article: PeerJ, doi: 10.7717/peerj.21176