[Coral-List] White spined diadema
Martin Moe
martin_moe at yahoo.com
Mon May 12 09:31:28 EDT 2008
On white spined Diadema,
I've seen and collected numerous white spined Diadema. The cause and occurrence of the white spines is not clear to me. I know that on the arms of the urchin, yes, they have arms, sort of. On the test there are 5 triangular plates, the ambulacral plates, that are like the 5 arms of a starfish but as if they were folded up from the aboral pole and fused into the spherical body. The tube feet of the urchin are located on the edges of these plates. The spines that originate on these ambulacral plates and the spines that originate from the interambulacrum areas are generally indistinguishable during the day, but at night the spines on the 5 ambulacral plates are usually white or whitish and give the urchin a sort of striped look. This the nocturnal color phase. Juveniles have spines with variable dark and white ringed spines. From working with my brood stock, I got the impression that it is the older individuals that seem to retain the nocturnal coloration
during the day. In my brood stock I have two individuals that permanently retain white spines on the ambulacral plates, these two are males.... But there are other males that do not retain the nocturnal coloration. And I have collected some individuals with all brilliant while spines, from not particularly deep in the reef, and with "normally" dark purple colored individuals in the same area. I have had individuals that were all white on collection become dark after a time in the brood stock tank and some that permanently retain full or partial white coloration for a year or more.Usually it is the larger (older?) individuals that exhibit partial or total white spines, but some smaller individuals also have this coloration. Also, the incident of white spined individuals seems to vary in different areas of the reef. Some areas seem to have considerably more individuals with partial or full white spine coloration than other areas.
So, basically, some Diadema, a relatively small percentage, have a permanent or long term, all or partial white spine coloration, and I don't know why this is so.....
Martin Moe
----- Original Message ----
From: Robert Miller <rjmiller1 at gmail.com>
To: John Ware <jware at erols.com>
Cc: coral-list at coral.aoml.noaa.gov
Sent: Saturday, May 10, 2008 1:34:00 PM
Subject: Re: [Coral-List] White spined diadema
Hi,Somewhere out there is an old study that showed, I believe, that juvenile
Diadema that were raised in the dark were all white. Other studies have
shown, as John Ware says, that more white ones are found deeper and under
rocks etc. Unfortunately I don't have the references now.
good luck,
Bob
On Fri, May 9, 2008 at 10:06 AM, John Ware <jware at erols.com> wrote:
> Stuart,
>
> I was hoping that someone who had firm knowledge would respond, because
> my memory is old and feeble. Some 15 or 20 years ago I read a paper
> (which I cannot recall or find) that stated that the white-spined D.a.
> were more often found in low visibility environments. At least that is
> my recollection.
>
> John
>
> Stuart P. Wynne wrote:
>
> >Dear all,
> >
> >
> >
> >I have been trying to find references to the white spined Diadema
> >antillarum that I sometimes see in our waters here in Anguilla. As I am
> >not privy to open access (but please let us not get onto that subject
> >again!) I have been struggling to find any mention of the causes for
> >this, only the fact that it is a fairly common thing to see. I guess it
> >is a lack of pigment? As all such individuals I've seen here are large,
> >could it be something that signifies they are reaching old age? Does it
> >indicate a lack of something in their diet? Pollution/eutrophication? If
> >anyone has any ideas/knowledge I would love to learn.
> >
> >
> >
> >On a separate note I would like to send out a big thank you to the three
> >people who posted on the coral-list vol 59 issue 6. For the first time
> >since I have been a member I did not have to wade through endless reams
> >of old postings (that had been left tagged to the bottom of their entry)
> >while trying to figure out which messages were the new messages. Well
> >done! Maybe we can keep this up?
> >
> >
> >
> >
> >
> >Stuart Wynne
> >Marine Biologist
> >Department of Fisheries and Marine Resources
> >Anguilla
> >
> >
> >
> >
> >
> >
> >
> >
> >Government of Anguilla
> >_______________________________________________
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> >Coral-List at coral.aoml.noaa.gov
> >http://coral.aoml.noaa.gov/mailman/listinfo/coral-list
> >
> >
> >
>
> --
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--
Robert J. Miller
Marine Science Institute
University of California, Santa Barbara
Santa Barbara CA 93106-6150
(805) 893-7295
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