lpearce's picture

Seven-armed Starfish

Observed: 14th June 2006 By: lpearcelpearce’s reputation in Invertebrateslpearce’s reputation in Invertebrateslpearce’s reputation in Invertebrateslpearce’s reputation in Invertebrates
Seven-armed Starfish
Description:
Identifications
Species interactions

No interactions present.

Comments

Stacey Cougill's picture

I like your photo! Roughly

I like your photo! Roughly how big was the starfish? I believe they can grow up to 40cm across.

iSpot Biodiversity Mentor - London

lpearce's picture

The hand is about 15cm for

The hand is about 15cm for wrist to end of fingers, so I would say the starfish about 35cm across. It certainly was bigger than others we have seen. Do you think it was an Luidia cilaris?

Les Pearce
Photos- http://www.flickr.com/photos/assyntnature/
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Wildlife of Assynt

the naturalist man's picture

Luidia cilaris

This is Luidia cilaris. Two features are a give away, firstly it is the only British starfish with seven arms and the fringe of white hairs, or cilia (hence the scientific name). The cilia are used to help the starfish bury itself in sand or mud, usually below the low tide mark. The Astropecten species also have cilia but they are shorter and stiffer; also they always have five arms.

They readily shed their arms therefore I assume this one was dead as you were able to lift up the arm. I had one these loose an arm just from me touching it, therefore I never do anymore. Unlike the common starfish (which again always has 5 arms)which I've handled many times and never had one loose an arm.

I do a lot of rockpooling and some sand sampling with students and school children, as well as for pleasure, and I've only ever found these washed up after a storm, usually dead; though I have found a handful of live ones.

Warning: do not read this if you have a delicate disposition! The starfish have a wonderful way of feeding, it grabs shellfish, other starfish etc. with the suckers on its legs and passes the prey to the centre where it has a small hole on its underside. The hole doubles up as mouth and anus. Once the prey is by the 'mouth/anus' its stomach turns itself inside out emerging through the 'mouth/anus' like a floppy balloon. The starfish then engulfs the prey and if it is small enough the starfish pulls it within the 'mouth/anus' where it is digested. The stomach then turns inside out again and ejects the waste out through the 'mouth/anus'. Stomach turning isn't it?

Graham Banwell

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dejayM's picture

commenting

Nice stuff from Graham there. This, informative commenting, seems to be lacking nowadays.
And why, after all this positive commenting, and nearly four years, has only one person agreed?
Derek
Trawling history - purely personal