28 June 2011

Sea urchins of the Aegean

Sea urchins are fun as long as there isn't one under your bare foot.

These urchin tests were all from the same location in western Turkey. Their differing colors may indicate that they belong to different species. Alternatively, they may be color variations of one species. But there are also size differences: the reddish ones never seem to grow as large as the green or the purple ones.

Leave a comment if you think you can enlighten us.


Anonymous said...

How big are they and are they a bit flattened in shape? I am far from being an echinoderm expert, but here goes anyway... they look rather like the tests of a similar British species, which is Psammechinus miliaris (Müller, 1771). However I see (thanks to the website WoRMS), that in the Mediterranean Sea, including the Aegean Sea, there is a congener instead, Psammechinus microtuberculatus (Blainville, 1825).

I would guess the purple and green ones are color varieties of the same species. The orange ones look as if they might be a different shape in profile, as if they might be less flattened, or are they exactly the same shape as the others?

Susan J. Hewitt

thepowmill said...

I am no expert in any of this...but I can never fail to appreciate the gems that nature provides . Your blog is full of interesting and in this case beautiful gems . Thanks.

DPC said...

The green and purple ones are not variations of the same species! The greens are Paracentrotus lividus while the pinkish ones (second column) are Arbacia lixula. The large purple one is Sphaerechinus granularis. All are pretty common throughout the Med.


David, thanks!

Anonymous said...

I bow to your superior knowledge David!

Susan J. Hewitt

Silly Little Sheep said...

I think the big purple one is Sphaerechinus granularis, I found many of these in Croatia. The living animal's spines are usually dark and their ends are lighter colour, quite variable but white-ish, can be slightly tinted with some other colour. The spines themselves are not sharp and you can easily pick the animal up and have it in your hand, you will not get hurt by it.

The smaller pinkish ones that are in the middle could be Arbacia lixula, very sharp black spines, difficult to tear off rocks because of how spiny they are.

Hope I helped, I have seen many of these and they are wonderful :)