From collecting to identification
Article | Updated 4 weeks ago
Curators at the Western Australian Museum are regularly involved in scientific projects that aim to increase our understanding of Western Australian biodiversity and biogeography. In this podcast Curator of Fishes Dr Glenn Moore explains the methods used to identify fishes.
Please Note: Podcast was recorded early 2014.
At the moment I am involved in two projects in the Kimberley – I am involved in more but two main ones at the moment. The first one is the Woodside funded project which is looking at all the marine life in the Kimberley. I am working just on the fish with Sue (Sue Morrison, curator at the WA Museum, ed.) and all the other main marine groups have been studied at the same time which is what makes it really unique, because most other groups – people - research teams - that go up, they work on just one or two, maybe they just work on the fish, or the fish and the corals or something like that but we try to cover as much of it as we can. And so we have been going for five – this will be our fifth year, this year, for this project - and we have covered a whole bunch of places, basically most of the Kimberley and the offshore areas. I think it is like over four hundred thousand square kilometres, a huge area, I mean it’s bigger than half of Europe, it’s massive, absolutely enormous.
And so then we do these transects, so for fish we mostly do these UVC’s, these Underwater Visual Census, and that gives us a huge number of species but we don’t have specimens associated with them so we need to trust ourselves, that we know what we are looking at or, best still, we try to collect them, using either chemicals or fishing or a spear sometimes.
Then we try to identify them, and first of all we need to curate them so we need to get them into the collection, so when they come back they get fixed in formalin, vertebrate tissue needs to be fixed in formalin otherwise it goes all funny, so it goes for a formalin bath for a week or so depending on how big it is and then it gets soaked out in water and then it is stored permanently in ethanol, and then from that specimen we can start to identify them, make sure we know what we do have and during that process I guess you would – that’s when we’d find out if there is anything that doesn’t quite match, a new species for example, things like that, things that don’t quite – when we do these counts and things like that - they don’t just seem quite right, so occasionally we bump into some of those, and then we might talk to our colleagues, people that might have a bit more experience in that particular group, we can talk to them and see what they think and sometimes they may already have identified that there’s something different. Other times we might even just be catching groups of fish that no one has really looked at yet. Generally to identify that you do have something that is different, to know that you have got something different it means that you have to look at not just that specimen or that range of specimens, you also need to look at other specimens that are known from elsewhere, so that you can compare them too, because then how else do you know it’s different? So you often get loans from other museums or you look through our collections and try and figure out what we’ve got and compare it to what we have just collected. That’s probably the most important step and it is probably amongst the most tedious part of it because you try to look at as many specimens as you can to understand how much variation there is within each one, and that is the point that you can then try and decide whether or not you think it’s new. Hopefully you have a piece of tissue and you can send the tissue off for some genetic analysis, but of course the genetic analysis is only meaningful if you have got genetics for the other one as well, so sometimes it helps, sometimes it doesn’t really help but that’s certainly an important point. Then it becomes a matter of formalising it as a new species so that means describing all the characters of that species and how those characters differ from other closely related species.
You need to also set up a series of types when a new species is described. So the types are the specimens that are chosen to represent what that species looks like. So you might choose specimens that are, perhaps, the most ‘average’, the most typical of that species and then you have one individual that is designated as the holotype and that’s the primary type, that is the main one, and if there is ever any doubt about what this species is supposed to look like that is the specimen you go to. Then preferably you have a range of secondary types, that are called paratypes. There is only one holotype, but paratypes you could have more than one. Paratypes have a couple of purposes. One is that they try to represent a bit of the variation within the species. If the male a holotype you may try to have some females paratypes or some different sizes, so you get a bit of size range, or sometimes they have you know , like if the scale count maybe ten to twenty for example, and you may have some of the ten end, some of the twenty end, just so you have a range of the variation within the species, that’s one important point of paratypes. The other thing about paratypes is just to have some more representatives of – that were identified by the experts, by the person that has named the species and they have said these are definitely this species and then you can split those into other institutions: some might be stored at our museum, some in another museum, and so forth, so if something happens at our collections there’s some backups, if you like. They are the key elements of describing a species, and they are really really important, the types are critical, they are gold, they are the most important things in our collection.
We have lots and lots of just voucher specimens that are not types at all, they don’t fit into any other type at all. Again by having these specimens, and it is the same when we are collecting up here on these field trips is having a specimen in a jar is a very powerful record because these UVC’s that I do, the visual ones, there is no evidence, there is no proof, that what I saw, or first of all that I saw it, and secondly that I got the identification right. What we have here, and that is the strength that museums have and that no other organizations in the world have, I mean that’s all – because museums have a collection that specimen out there has a date and a place, and so we know that that specimen occurred at that spot at that date and we have got proof of it. And you can go back later on, and for example if you find something that’s a new species but it looks very similar to something else it might having called the wrong species name and so now when you go to the collection you can go back to the specimens and look at it and go well it was actually something else. That’s why the collection is so important, and that’s why museums are unique, no one else can do that. No one else can actually go back to a specimen and confirm that they are right.