Tuesday, March 11, 2008

Weekly Urchin - Dominican Republic edition

In anticipation of Linda's and my vacation to the Dominican Republic in a few days, I give you Diadema antillarum, the long-spined sea urchin. This urchin is a keystone herbivore on coral reefs throughout the Caribbean and one I hope to see during our vacation.

This particular species was once a dominant part of coral reef communities. However, a catastrophic die-off in 1983, the result of an unknown pathogen, resulted in an over 97% mortality rate Caribbean-wide - the most severe mass mortality ever recorded for a marine organism. The disappearance of D. antillarum from the reefs lead to the proliferation of macro-algae which quickly overtook the coral reefs. This unchecked algal cover resulted in coral die-off and prevented new coral recruitment. The result was an overall deterioration of reef communities. Although there have been reports of localized D. antillarum and subsequent coral reef recovery (Edmunds and Carpenter 2001), populations remain low even decades later (Lessios 2005 - pdf). Continued research and coral reef restoration using reared and/or transplanted D. antillarum are currently underway.

Changing tacks a bit, below is a stunning video of D. antillarum development from Diadema.org. The video is a bit long, but it comes complete with a soundtrack by Enya (I believe) and contains amazing footage of a metamorphosing larva - if nothing else, you need to watch for this (about a third to half-way in).


Unknown said...

You think you could arrange a spine-sharing plan between Diadema antillarum and a certain basketball team come tournament time? - thx

as for 90% of the population, you have us confused with Idaho. Just like you're all a bunch of greased-hair, chipped tooth, leather-jacket wearing drunk racists with at least two friends named "Sully". Wicked cool.

Linda B. said...

Maybe I'm missing your reference, but if you're referring to us NewEnglanders usually we're a bunch of Red-Sox or Bruins jacket wearing drunk racists holding DunkinDonuts coffee styrofoam cups with one friend named Big Joey and the other named Little Joey (and it case you didn't know, Little Joey is usually bigger than Big Joey). And it's wicked piss-ah

Steve said...

I highly doubt they were the genus that you are mentioning, but when I was snorkeling in the Dominican Republic in 2006, there were quite a few urchins to be seen.

Dale Hoyt said...

Many years ago, in the Virgin Islands, I discovered (for myself) that Diadema could orient its spines toward a disturbance -- my pointing finger. I never noticed it jabbed up the length of the digit until a little blood leaked out the end of the finger. Do you know how the urchin was able to sense my finger? Was it just shadow or was it pressure waves in the water?