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A starfish eating a shark?

By Eleonora de Sabata, 5th April 2014

I knew there was something weird in this starfish, as I swam past it looking for newly-laid nursehound eggcases to film for my project (I am studying this spectacular seamount which is a kindergarten for nursehound sharks Scyliorhinus stellaris). But time flies at 35-40 meters of depth, and I had no time to waste investigating anything that wasn’t shark-like. So I concentrated on my task, and only remembered about the starfish it as I swam past it coming back to the surface. But my air supply was getting low and long minutes of deco time awaited, so I only quickly shot a few seconds of video as I went past and headed to the boat.
Bad move!
Because once I looked at the video, then at my desk in Rome, I realised that I may have witnessed – for the first time ever! – a …starfish eating a shark.
What was odd about this starfish was that it was almost flying: it hung on a string between two seafans – a very odd position for a starfish. The end of the string was very, very curly – exactly like the curly tendril that eggcases are tied with to seafans.
Could it be then that this starfish was actually wrapped around and possibly preying upon the little nursehound embryo?
The spiny starfish Marthasterias glacialis is one of the most voracious starfish we have in the Mediterranean. It feeds on various animals such as molluscs, shellfish and echinoderms: the relatively soft eggcase of th nursehound surely is no defence against this predator.
If only I had realised what was gong on, I could have had a better look. So now I can only go back (diving tomorrow), hoping to find the same spot and see if there is any trace of this drama left.
But I will surely keep an eye on those starfish, just in case I might see another one having a feast. And – next time I see a starfish swinging on a string, I surely will take a better look!

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