How do you electronically tag a starfish?

Dr Miles Lamare, from the University of Otago, talks about the challenges of attaching electronic tags to starfish.

Point of interest Starfish is the common name for a group of animals called sea stars. Sea stars are actually part of the phylum echinoderm and are related to sea urchins, brittle stars and sea cucumbers – they are not fish at all!

Transcript

Dr Miles Lamare

We were puzzled how we were going to attach a tag to an animal, because what it might do is just shed the arm that the tag was attached to. So we tried different things, we made a little backpack for them, and they were a bit like a Houdini – they kept getting out of it. Even after a night – we’d leave them at the lab overnight – we’d come back, and they’d got out of these packs, so we weren’t really sure what we were going to do. And as a last desperate measure we said we’ll pierce one of the arms with stainless steel wire and we’ll attach a tag, by that thinking this is probably not going to work cause they’ll just shed the arm where the pierced tag was attached to. And it worked, actually, so we were pretty happy.

So we’d take stainless steel wire, we make a custom-made wee loop that pierces the arm, and then we just attach it that way. And that works really well. What we needed to do was also test that the effect of tagging didn’t affect the animal in any way.

So it’s no point tagging an animal and then trying to do research on it if its behaviour has completely changed because it’s got this tag stuck to it – maybe, you know, if its feeding stopped or it’s unhappy or unhealthy. So we had to do a lot of tests in the lab.

We basically used a standard technique for assessing the health of a starfish and that is you turn it upside down and you record the length of time it takes to right itself. And if you’re fit and healthy and not physiologically stressed, you will right yourself quickly, and the more unhealthy you are, the more physiologically stressed you are, the slower or the longer it will take for you to right yourself. And what we found was there was no effect of tagging on feeding rates, health or the way they moved, so we were pretty confident that the animals that we tagged would be representative of what a normal starfish would be doing.