Fluorescing Corals, Shellfish Amnesia, Starfish Exorcisms | July 13, 2015 Issue - Vol. 93 Issue 28 | Chemical & Engineering News
Volume 93 Issue 28 | p. 56 | Newscripts
Issue Date: July 13, 2015

Fluorescing Corals, Shellfish Amnesia, Starfish Exorcisms

Department: Newscripts
Keywords: corals, domoic acid, starfish, ocean chemistry, fluorescence, GFP
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Coral color show: Red Sea corals that don’t fluoresce in shallow waters (left) fluoresce a fabulous red in waters deeper than 100 feet.
Credit: PLOS One
Echinophyllia aspera coral only turn on fluorescence at depths below 100 feet.
 
Coral color show: Red Sea corals that don’t fluoresce in shallow waters (left) fluoresce a fabulous red in waters deeper than 100 feet.
Credit: PLOS One

It’s a categorical truth that the best way to while away the scorching days of summer is to lie next to a large body of water, contemplating the awesomeness living below the surface.

Consider, for example, the rainbow of fluorescing corals just found deep below the surface of the Red Sea near Eilat, Israel. Until recent scuba technology advances, most divers needed to limit their underwater exploration to about 100 feet below the surface. But many corals that live in shallower zones also exist in much deeper water, and many of these corals are turning on some awesome fluorescence at these so-called mesophotic depths.

Fluorescence at shallower depths is not unheard of, but it’s usually only green in color. This shallow-depth fluorescence helps the corals protect themselves from light damage. What’s surprising is that many species of corals are fluorescing yellow and red in deeper waters, and they do it so brightly that the fluorescence is visible to the naked eye (PLOS One 2015, DOI: 10.1371/journal.pone.0128697). Still to be discovered is why the corals are turning on the rainbow light show.

The Newscripts gang is tempted to book a vacation to the Red Sea to check out the crazy corals, especially given this alternative: Being a seafood-eating beach bum in California could give us amnesia. The California Department of Public Health sent out an advisory last month telling folks to avoid consuming “recreationally harvested” mussels and clams, all kinds of anchovies and sardines, and the internal organs of crabs from Monterey and Santa Cruz Counties.

The problem is an algae-produced molecule called domoic acid. This neurotoxin bioaccumulates in seafood, isn’t destroyed by cooking or freezing, and at poisonous levels causes “vomiting, diarrhea, abdominal cramps, headache, and dizziness.” At even higher levels, domoic acid—which we think should be renamed demonic acid—gives victims “trouble breathing, confusion, disorientation, cardiovascular instability, seizures, excessive bronchial secretions, permanent loss of short-term memory (a condition known as amnesic shellfish poisoning), coma, or death.”

Although the compound is a threat to many seaside communities, Japanese people have also been using it for centuries to expel parasitic worms. You know, like a wormy exorcism. Yet another reason to call it demonic acid.

Two students describe how wily starfishes expel scientific tags.
Credit: University of Southern Denmark

Speaking of seaside exorcisms, two University of Southern Denmark students have discovered that starfish are impressively good at expelling large foreign objects lodged in their bodies. The students had been tasked with tagging starfish so that the animals could then be followed in natural environments. But somehow the tags kept ending up at the bottom of the starfish cage.

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Outta here: Starfish internally tagged with a magnetic stir bar can expel a foreign object out of the tip of an arm.
Credit: U of Southern Denmark
Starfish internally tagged with a magnetic stir bar can expel the foreign object out of the tip of an arm.
 
Outta here: Starfish internally tagged with a magnetic stir bar can expel a foreign object out of the tip of an arm.
Credit: U of Southern Denmark

Refusing to be bested by five-armed echinoderms, the duo tried tagging the beasts with a magnetic stir bar, which they tracked with a magnet.

To their surprise, the starfish used contractions to propel the unwanted tag through the central part of the body and out of the tip of an arm. The forcible expulsion, with a charming narration from the students, was caught on video.

“We don’t know why or how it does it, but it’s not very pleasant to have foreign objects inside oneself,” notes Trine Bottos Olsen, one of the students, with typical Scandinavian understatement. “The bad news is we still don’t know how to insert chips into starfish.”

 

Sarah Everts wrote this week’s column. Please send comments and suggestions to newscripts@acs.org.

 
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