One of the arguments for learning scientific names is that they are stable and reliable compared to common names. Many marine animals have one scientific name, and multiple common names, often depending on the location. For example a Jewfish (NSW) is called a Mulloway in Vic, Butterfish in SA and Kingfish in WA. But scientifically they’re all called Argyrosomus japonicas. One common name can mean several species too, for example “sea bass” is the name used for over 20 species around the world.
So, start learning the double barrelled-scientific names and you’ll be set for life, right? Sort of. Unfortunately the two-part scientific names contain a hierarchy which can change if an organism is re-classified. This is happening at the moment with those favourites of many divers, the nudibranchs. Three years ago, that regular of any dive around Sydney, the black-margined nudibranch, was renamed. And there are more to come.
The first of the two parts of the scientific name, the genus, indicates species which are closely related. Amongst the nudibranchs, for example, there are several genera, each with a collection of species within. For example chromodorid, glossodoris, ceratosoma and hypselodoris. So long as the black-margined nudibranch Glossodoris atromarginata remains a glossodoris, its name is safe. But what if scientists decide it’s not a glossodoris? Then the name will have to change. This is happening at lot at the moment, as DNA analysis shows that species that we thought were closely related aren’t, and others which we thought were distant cousins are actually closely related.
So “Glossodoris” has been dropped, and the black-margined nudibranch is now considered to be a “Dorisprismatica”. Its name is therefore now Dorisprismatica atromarginata. There is a site you can go to to find out the correct scientific name of a species, with the wonderful name WoRMS – World Register of Marine Species. Here is the entry showing the name change of the black-margined nudi http://www.marinespecies.org/aphia.php?p=taxdetails&id=214507
Most of the time, scientists keep the second part of the name, the species (atromarginata) the same when they make a re-classification. That helps a bit… but they don’t always do it. For example when the common red, white and yellow nudi Chromodoris splendida was re-classified into the new Goniobranchus genus, the last couple of letters changed so it’s now Goniobranchus splendidus.
Of course, to do DNA analysis you need tissue samples, so at this point scientists have worked through most but not all species of nudibranch. Many Chromodoris have become Goniobranchus, many Glossodoris have become Dorisprismatica and many Hypselodoris have become Felmida. But the Australian endemic species, like Hunter’s, Thompson’s, Tasmanian and Loring’s nudibranchs haven’t been analysed yet as there were no samples available. Stay tuned to find out how these will change, as a couple of URG members have been gathering samples for the scientists at SCU.