A deep sea creature thought to be part of the large anemones, with tentacles over 2.2 meters in length, actually belongs to a new order of animals .
The discovery of this new order of Cnidaria (a phylum that includes jellyfish, corals, sea anemones, and their close evolutionary relatives) has been made possible from a study by the Division of Invertebrate Zoology of the American Museum of Natural History (AMNH ) in New York, in which the first evolutionary family tree of sea anemones based on DNA analysis has been developed.
According to Estefanía Rodríguez, deputy curator of the Museum and co-author of the research, the finding is like finding the first member of a group such as primates or rodents and tells us that there is still much to discover in the ocean.
The international team that has developed the research, in which Alejandro Grajales, from the American Museum of Natural History, Verena Häussermann, from the Pontificia Universidad Católica de Valparaíso in Chile, Meg Daly, from the Ohio State University and scientists from other institutions in Brazil and Germany, it took four years to organize the family tree of sea anemones “naturally” or phylogenetically, based on their evolutionary relationships .
Sea anemones are polyps that spend most of their time attached to rocks on the seabed or on coral reefs. Although they vary widely in size and color, they have very few defined structures, making it difficult to classify these animals based on their morphology alone.
Anemones are very simple beings and they are grouped due to their lack of certain features , such as the skeleton, or because they do not form colonies as corals do. So Rodríguez and his collaborators found errors in the traditional classifications of these animals when they examined their molecular data.
The researchers compared particular sections of DNA from more than 112 species collected from all oceans. The species that turned out not to be a sea anemone was known until now as Boloceroides daphneae , and was discovered in 2006 deep in the Pacific. But the new study shifts her off the evolutionary family tree of anemones and places her in a newly created new order. Its new name is Relicanthus daphneae and it lives near hydrothermal vents.
It is an example of convergent evolution, of a species that evolves independently towards similar traits than other species of different lineages but subject to the same environmental requirements. Although it looks a lot like a sea anemone, it is not.
The new research reveals that while anemones, through millions of years of evolution, lost certain characteristics, R. daphneae never did. “Placing these animals in the same group would be the same as classifying worms and snakes together because they have no legs,” says Rodríguez. For now, Relicanthus daphneae is the only species in this new order.
