The layer of sand on ocean floor is home to a large part of the vast diversity of marine species. Species representing almost all classes of marine animals live here. The genus Grania, which belongs to the class of annelid worms Clitellata, is one of them.
Grania the globetrotter
Grania is a worm around two centimetres in length and mostly white, which is encountered in marine sand throughout the world, from the tidal zone to deep down in the ocean. The researcher Pierre De Wit, at the Department of Zoology of the University of Gothenburg, is analysing exactly how many species of Grania there are and how they are related to other organisms.
Four new species
De Wit has conducted studies at the Great Barrier Reef in Australia, where he and his colleagues have found four entirely new species of the Grania worm. One of them is the beautifully green-coloured Grania colorata. “These worms are usually colourless or white, and we have not been able to work out why this particular species is green,” says De Wit.
De Wit has also found a previously unknown worm in Scandinavia, dubbed Grania occulta, which can only be distinguished from a previously known species by DNA. The worms’ genetics show that the evolutionary history of the two species is in fact entirely separate, and that one of them is actually more closely related to a species that looks completely different.
“Species that were previously regarded as the same may prove to have a completely different function in the ecosystem, and have different tolerance of environmental toxins, for example. It is obviously important to know this in order to be able to take the right action to protect our fauna,” says de Wit.
The doctoral thesis Systematics of Grania (Clitellata: Enchytraeidae), an interstitial annelid taxon was publicly defended on 5 March 2010.