If you have been following the Echinoblog's In-your-face and edgy Twitter Feed, then you have noticed this news jewel in the DestinLog.com,(based in Destin, Florida) that reports the following, curious recent event (highlights quoted below):
As the woman leaned over the boat...the unthinkable happened, the woman's dentures had fallen out of her mouth and into the Gulf. By the time the woman collected herself... the teeth were gone.The twist to this tale is that the missing teeth were found...Out on a dive near the bridge rubble, the divers came across the teeth, perfectly propped on top of a sea urchin.(emphasis mine)
“Sea urchins usually like to camouflage themselves in seaweed or whatever, and I am looking down there and the sea urchin had teeth on it,” Epp told The Log Friday morning. “I bust out laughing, trying not to choke on my water. I had to do a double take, I had to look back before I realized they were actually teeth.”
Wanting to help, Birchett took the teeth to the Fishermen’s Co-Op and had a sign made saying the teeth were located, hoping they would eventually be returned to their owner. Through the fishing grapevine, the connections were made and the woman was reunited with her teeth.Of COURSE, the article omits the MOST important details! What species?? Did you now that this sea urchins' biology may have been directly related to the rediscovery of those dentures?? And what would this have to do with the deadly Ultraviolet radiation in the tropics?
What about the perspective of those dentures from the Sea Urchins' side??? Who could have REALLY used those dentures??
Let's find out!
Species! So, we don't know exactly which species it might be, BUT given that its Florida in the Gulf of Mexico, its probably one of two- Lytechinus variegatus -a widespread Atlantic species
Both are very abundant and commonly encountered species that practice what's known as "covering behavior".. and much of the information in this post comes from two very informative papers by Katherine Amato et al. in a 2008 issue of the Bulletin of Marine Science and a paper by Jessica Sigg et al. in a 2007 issue of the Journal of the Marine Biological Association of the United Kingdom.
What is "Covering Behavior"?? Put simply-Sea Urchins cover their body surface with nearby debris. Presumably, these items are held fast by tube feet on the sea urchins' body surface. Such as this one..
This is practiced by many species of sea urchin from around the world, such as this species from the Galapagos..
Here is a video that shows "covering behavior" called "masking" by some, set to a delightful Benny Hill soundtrack...
Why Do Urchins Practice "Covering Behavior"?? And What Does This Have to do with Dentures anyway???
But believe it or not-there may have actually been a GOOD reason for that urchin to be doing so!
Its tied to WHY these urchins practice covering behavior in the first place.
Sigg (2007) and many other authors have presented evidence that the reason, at least some urchins cover themselves with seeming debris is to protect themselves from ultraviolet radiation, which could conceivably damage their gonads or other tissues (as in most animals).
But, some urchins cover themselves with seaweed versus other species which do so with pebbles and shells? Why do these vary?
Below is Fig. 1 from Amato et al. who compares the preferences of two sea urchins (Lytechinus on the left in white versus Tripneustes on the right in black).
Some dynamics (Based on tests of Jamaican species)
1. Lytechinus was much more inclined to cover up more of its surface than Tripneustes.
2. Lytechinus likes covering itself up with rubble. Whereas Tripneustes prefered covering itself up with the seagrass Thalassia.
3. But there was some variation depending on the availabiity of materials in the area.
Its choice of rubble further follows that trend in that it seeks out items that will prevent penetration of the sunlight.
The lab work of Sigg et al., suggested that Lytechinus was indeed suceptible to UV radiation and not simply to light intensity or brightness. Lights alone, apparently did not compel the urchins to cover themselves but UV exposure did, and in fact, UV radiation increased covering behavior!
Given that bunches of small sized shells would be easier to hold onto why choose bigger more intermediate sized shells and pieces of rubble?
Probably because medium sized bits offer better protection from UV exposure. There's no "cracks" or openings if you have fewer, larger sized pieces!!
So finally, this brings us back to the image that accompanied the orginal article in the Destin Log! An image which tells us a LOT about the sea urchin species in question!....
Assuming this wasn't a miscellaneous assortment of shells for a photo op.. this tells us that the likely candidate was Lytechinus variegatus! (otherwise we would be likely seeing more seaweed!)
and the dentures??? Lightweight AND broad enough in size to be capable of broad UV protection/coverage!!
Now, you know the REST of the story! A Florida woman's 1200.00 dental costs recouped? or that individual Lytechinus' best defense against the terrible onslaught of UV radiation??