Echinoid Id Help

[jivv]

having trouble id'ing this, help please? have a feeling its a heart urchin, but not 100% certain.

thanks

[Fossildude19]

What is the size of this, and where was it found?

Regards,

[jivv]

hi there, about 20cm and it was handed to me, I don't know about its origins

[FossilDAWG]

Is it even a fossil? It appears to be completely hollow, and the small plates around the anal opening are rarely seen in fossil specimens. It looks recent to me.

Here is a web site with images of most recognized echinoid genera, at least. Perhaps you will be able to find a match to your specimen. You should start with familiarizing yourself with echinoid morphology, so you will be able to understand the diagnostic features in the descriptions of genera and not be misled by superficial similarities.

Don

[Plax]

dead Eupatagus?

[tmaier]

I don't think it is a fossil. It is likely to be a modern Spatangus purpureus, the common purple heart urchin found in the Mediterranean region.

http://www.echinoids.nl/Echinoids/Spatangus-purpureus/Spatangus-purpureus.htm

EDIT:

Also found in the Atlantic from the Azores up through the British Isles and into the North Sea. It has a broad territory.

Edited November 13, 2014 by tmaier

[Coco]

Hi,

I am sure it is a recent species. But i have some difficulties... I think Maretia planulata from New-Caledonia (but yours is big...), Eurypatagus ovalis from Philippines, but I am not really sure. I have to consult " my Bible " regarding current sea urchins, but at the moment it is the hour to eat !

Coco

[tmaier]

Definitely not Maretia planulata

http://www.echinoids.nl/Echinoids/Maretia-planulata/Maretia-planulata.htm

and not Eurypatagus ovalis

http://www.clarenbach.org/My%20echinoids/Irregulars/Eurypatagus%20ovalis.htm

[Coco]

Tmair, I said : "but I am not really sure"

Now I had a look on a book, and I think it could be Spatangus californicus. And as you know my friend Bas's website, you will see that his sea urchins is flashy and that it doesn't allow to see détails. As for Clarenbachs's website, he hasn't this species. And pics of this species are rare on the net.

Coco

[tmaier]

Nope, I don't think it is Spatangus californicus

http://www.echinoids.nl/Echinoids/Spatangus-californicus/Spatangus-californicus.htm

[Harry Pristis]

hi there, about 20cm and it was handed to me, I don't know about its origins

20 cm? TWENTY CENTIMETERS?!! Holy cow!

[tmaier]

20 cm? TWENTY CENTIMETERS?!! Holy cow!

This one is reported at 25 cm.

http://www.marlin.ac.uk/speciesinformation.php?speciesID=4350

[Coco]

I said higher that the sea urchin pic of the Bas's website had a blow of flash and that it didn't allow to see any détails, and it is exactly this one that you show ! Have you an idea of this recent sea urchin identification ? Say "no" is good, but say "why it is no" is better and helpfull for all.

Here is a pic from Heinke Schultz, a German great name of sea urchins collector. It is a Spatangus californicus. Please, explain me why Jivv's sea urchin isn't this species, because I don't see why.

If I made a mistake it is not a problem for me, I would accept that, but I would like to know why

Coco

[tmaier]

This one is reported at 25 cm.

http://www.marlin.ac.uk/speciesinformation.php?speciesID=4350

Wait, that web page says the IMAGE is 25 cm. Most all of the other web sites I find list the maximum size of purpureus as 12.5 cm.

[Coco]

Whom who do you answer ? To me ? You do not answer my question...

Coco

[tmaier]

I said higher that the sea urchin pic of the Bas's website had a blow of flash and that it didn't allow to see any détails, and it is exactly this one that you show ! Have you an idea of this recent sea urchin identification ? Say "no" is good, but say "why it is no" is better and helpfull for all.

Coco,

I provided images to back up my guess. You didn't. I'm sorry, but I need evidence and not just your say-so. You disagreed with my opinion by ignoring it totally, with no feedback from you as to why you disagree with me. I don't accept that as proof.

Notice that on the image you provide above of Spatangus californicus the keel sticks up, but in the specimen under question is sinks down, just like on the purpureous. Maybe more views would add more evidence to your argument, but the ventral view doesn't do it.

This californicus and the purpureus are amazingly similar, but I'm sticking with purpureus. Another reason I jumped on the purpureous was that it is very common around England, and is commonly available in seaside shops around western Europe. The post is coming from England. Not really good evidence, but that is what put me on to it. The californicus is much more rare and I doubt they sell them in England.

Also the size. The purpureous is more than twice the size of californicus, 60 mm compared to 125 mm. The poster says 20 cm, but that sounds like a guess and not a measurement.

So no hard feelings, but I think you dismissed my opinion to harshly, with just a "no" and no explaination why you were going a different direction. But I'm not offended, it's just a matter of opinion.

[Coco]

Hi,

To have a scientific opinion on this recent sea urchin identification, I sent photos to Heinke Schultz. Here is her answer :

"Dear Coco !
Please excuse the delay !!

I think your sea urchin will be Spatangus purpureus, when it came from England.
Yes, the anterior petals look strange with the lacking of pore-pairs in the anterior column, but I cannot find any other species.

If it does not come from England, it may probably be Spatangus capensis Döderlein 1905 from South Africa.

Have a fine day !!

Best wishes, Heinke"

So, you was right Tmaier

I didn't have some pics to explain the main difference I saw beetwen Jivv's sea urchin and Spatangus purpureus one. And I made some pics of mine several days ago :

And now, Jivv's one :

I didn't know how to explain what I saw, but Heinke done well ! I would have said that the lower ambulacra aren't "closed" and it isn't a characteristic of Spatangus purpureus...

Coco

[tmaier]

Excellent photos. It's good to have them on the internet for future reference, because as you say, the other examples where blanched out.

The way I researched this specimen was a bit unscientific, I didn't walk through the physiological features right away, I started out with the idea that this was a souvenir from a sea shell shop brought back by a tourist and "handed to" somebody. So I did a google search on " large heart urchin souvenir england". That brought me immediately to this species. Sure is nice having google do all the sorting out.

Some features of the physiology are either absent or become more pronounced as the creature matures, so an old adult will have slightly different morphology than a juvenile. This can cause a problem in classification when there is only an example of one, but becomes obvious when you have a bunch of them of various sizes, and can see the changes. Having many specimens in hand is also a good way to see a species difference, because when you line them up by size, the one that doesn't fit into the sequence must be a different species. So with species that closely resemble each other it is good to have examples of adult and juvenile to differentiate the specimen.

[Coco]

Hi,

Do you really believe that the pair of pores which ends ambulacra can disappear with the ageing of the sea urchin ? I think tubers can wear out, that spines can have a different look (as used teeth of some fishes), but the paires of pores ?

Having said that, it is always good to have several spécimens of different sizes for the same species.

You say to have a lot of spécimens in hand, can you speak to me about your collection of current sea urchins (now the sea urchin is identified, we shall not pollute too much the post of Jivv...) ?

Coco

[tmaier]

My collecting isn't just of echinoids. I have bivalves, gastropods, corals, and a lot of other things. I started to get more interested in "what is a species?", and these common fossils or even extant species are easier to work with because you get the complete organism and you can get a lot of them. It's an interesting hands-on experiment with taxonomy and attempting to "bin" these guys..

So I wonder if purpureus species has local variations? This is supposed to be a wide spread species through the Mediterranean and up and down the African/European coast. Constriction of gene flow through the Strait of Gibraltar may have caused a differentiation of the expressed gene pool. Sounds like an interesting study project. The samples should be fairly cheap and easy to get.

One similar thing that intrigues me is the King Conch here in Florida. It is a species that is found in shallow lagoons around the whole peninsula of Florida, and there is local variation from lagoon to lagoon. The species has a constricted gene flow like a "sting of pearls". The King's Conch is seldom found in deeper water, so this makes localized gene pools that are loosely connected by the few individual who do wander from lagoon to lagoon, keeping the species linked together by gene flow from lagoon to lagoon, in a line. It's an unusual gene flow pattern. An interesting thing to do would be to travel throughout the range and collect a good set of specimens every 20 miles or so. It would be even more interesting to map the distributed genome of this species, but that would be expensive.

http://en.wikipedia.org/wiki/Melongena

I wonder if purpureus has some of these loosely coupled gene pools in its wide range that have localized characteristics?

Anyway the original poster of this thread isn't showing a lot of interest in it, and I think it has wandered into becoming a lot more interesting than it started out to be, I don't think we are destroying it.

Edited November 23, 2014 by tmaier

[jivv]

Hi, thanks both of you for your help with this. Appreciate it.

I am curious, Spatangus purperus belongs to the family Spatangidae, however the family Loveniidae is very similar. How could/did you determine that this is in the family Spatangidae rather than Loveniidae? Someone told me it is Echinocardium cordatum, which comes under the family Loveniidae.

Again, thank you

Jivv

[tmaier]

Aside from looking at the pictures and trying to match them up, the proper way to classify a specimen is to find the verbal description that list the defining diagnostic features of the species. None of us has gotten to that point yet.

The person who makes the definition of the species already went through a lot of trouble to study other species of the genus, and neighboring genus, and crafted the species definition to show what is absolutely unique and distinguishing.

[tmaier]

Did you take a look at Echinocardium cordatum to see if you agree with that?

http://en.wikipedia.org/wiki/Echinocardium_cordatum