dejayM's picture

Sea stars

Observed: 30th April 2013 By: dejayM
Biological Recording In ScotlandHighland Biological Recording GroupOrkney Biodiversity Records Centre
dejayM’s reputation in InvertebratesdejayM’s reputation in InvertebratesdejayM’s reputation in InvertebratesdejayM’s reputation in Invertebrates
starfishes
tiny
Description:

Not THREE sorts but probably two - read the comments section.
I must admit, I spent an age trying to identify the darker one in P1 to find, eventually, that they may both be the same. P2 shows a very immature version at less than 2cms across.
For those who are put of by my American reference (Sea Stars) I simply prefer the name.
They are prolific and voracious munchers of their prey, so watch this scary movie http://deepseanews.com/2012/09/watch-helplessly-from-a-mussels-shell-as-...
"Unfolding like a fatal flower..."
That I am NOT completely certain about the purple one, nor should I be about the pink one) is reflected in my "It's likely...." Before my (still ongoing) 'apprenticeship' I had it tagged as Asterias forbesi; you may laugh!
The bright pink one, with turned ups from the 'wrists' is most probably Henricia sanguinolenta. But then, it might be Henricia oculata!
EDIT - See comments

Identifications
Species interactions

No interactions present.

Species with which Common starfish (Asterias rubens) interacts

Comments

JoC's picture

Asterias rubens

The complete H & R says of Asteris rubens that ‘the papulae usually occur in groups of three’, to distinguish it from Leptaserias muelleri which is a northern species not in the Handbook H & R. I had to look up papulae but I can now see them on your purple sea star (I am converted to your preferred name). so A. rubens for both I think.
I notice that you have other sea stars in your area such as Henricia sanguinolenta which is featured, but not fully identified as such, on an iSpot from St Abbs.

Jo

dejayM's picture

Thanks Jo

Leptaserias [sic] muelleri is here http://www.seawater.no/fauna/echinodermata/muelleri.html
Notice "The common starfish is also very similar, but the spines [have] a single point in contrast to the northern starfish, where each spine has a "rose" of usually 4 to 6 points."
I shall look much closer then!
And (of Henricia sanguinolenta)
http://www.habitas.org.uk/marinelife/species.asp?item=ZB1660
"It may be impossible to distinguish this species from Henricia oculata except in the laboratory."
Oh dear!
I was taken aback by the obvious presence of the madreporite - not knowing about these things!

ChrisMcA's picture

I'm pretty sure the 2nd pink

I'm pretty sure the 2nd pink starfish in the 1st pic is a Henricia,(from the colour, henricia sanguinolenta) so identifying these 3 as Asterias rubens is most misleading

dejayM's picture

pretty

Thanks Chris. I have amended the words a little to save a complete revamp of the post, just now. I will spend some time on this and read more about Henricia sanguinolenta.
I will say however that colours have been very variable, this year specially (I am told).
With that in mind I may simply replace the first picture with a MUCH more identifiable 'common'.

ChrisMcA's picture

Besides the pink colour (no

Besides the pink colour (no site/book I know mentions/shows such) there's the uniform texture, lack of line of white spines, or any white spines. Being young it hasn't the thin arms of an adult henricia, & upturned armtips are also characteristic of henricia's. See eg http://species-identification.org/species.php?species_group=echinodermat... (it mentions pink ones)

dejayM's picture

few spots

I am fast coming to the conclusion that you are right Chris.
That link shows a startling seastar - one that has enough differences to be certain. The upturned ends is a good key feature, it's mentioned elsewhere too but we can find A.rubens with similarities. Not so, specially, with spotlack - that could be an ultimate clue.
But I don't think I will change the picture because that will infect the whole post, making this comment trail pretty worthless. Trails like this one ought to be valuable to anyone who comes - does anyone come?
ð
Loads https://www.google.co.uk/search?q=asterias+rubens&safe=active&source=lnm...
But spot the Henricia in the White sea!