Talking to taxonomists: why identifying fish larvae matters
My name is Daniel Ottmann, and I have some news for you. This year, for the first time, the Larval
Fish Conference is taking place in Mallorca, and we organized a workshop to ID fish larvae. Let’s take a look. JEFF LEIS
What is a fish larva? There’s no single answer. Ontogeny is not easily divided into segments, in fact some invertebrate zoologists say that fish do not really have larvae, because they don’t metamorphose in the same way that so many invertebrates do. Why study ichthyoplankton? PETER KONSTANTINIDIS
It’s always the first step to a project, so it starts simple, by identifying the species
you are interested in, and if you know what species you are,
then you can go up to the bigger questions. JEFF L
What you’re seeing under the microscope isn’t what’s out there in the ocean. The types of characters we are talking about, you’ve heard some of it is body shape, developmental milestones, the gut morphology, the swim bladder, where it is. The medial fins and the paired fins. Dorsal and caudal are the medial; the pectoral and the pelvics are the paired. Different fins form in different ways: the
timing, the manner of development. It’s taxon-specific. And it’s about the time that you get
the caudal fin to be fully formed that the larvae are picking up
meaningful swimming abilities. FRANCISCO A.
Another very important character is the pigmentation pattern. All the fish larvae have a variety of pigments, but after the conservation in formalin, only the black pigment remains. Then, most of the descriptions are based
only on the melanophores, on the black pigment. This allows to identify even
at a species level. JEFF
And if you already know, if you are already an experienced larval identifier, you may want to start looking into fish larvae under the microscope. That’s really what you’re here to do, so have fun looking at these guys. STEFANIA RUSSO
I’m working on the microscope to understand if I’m able to recognize
other species of ichthyoplankton, and I’ve started with the shape of the body, and I use these keys. If I find the right shape and the right pigmentation, I write in my book the species. Everyone kind of has their own method
that they follow. PETER K.
To me, I always start with counting the myomeres, so that’s for me a very important part.
It’s the first thing I do, I look at the
body shape and the myomeres. JEFF
Use your eyes, and try to put everything together. The Germans have a word for it: Gestalt. ALLISON L. DEARY
The first thing I do is subdivide everyone into different body shapes: if you can get
piles of larvae that share similar body shapes it’s a lot easier, because then you can
focus your attention on those types of conditions and the species that have that. It makes it a lot easier versus just looking
at the whole dish individually. PETER K.
I think we need more people, we need more students
dealing with the larval stages because then you can really ask important questions, protect species better, if you care about the juveniles and the larvae and not only the adults, so that’s to me the crucial point. ALLISON
And so, these types of workshops are important because it passes on some of this knowledge, it exposes the next generation,
these early-career scientists to our field,
why it’s important, why we do it.