The Mucus-Shooting Worm-Snail That Turned Up in the
Florida Keys
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A male specimen of a worm-snail recently identified in the
Florida Keys. This one has been removed from its shell. Rüdiger Bieler
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Its bright orange and yellow and about
as long as your finger. It lives underwater in a limestone tube with an opening
at the tip about as wide as a pencil eraser. It glues its home to hard surfaces
and stays for the rest of its life. It’s a species of worm-snail that may never
have been seen before, and somehow it turned up in an artificial reef in the
Florida Keys.
On land, its table manners would not
seem so polite. It shoots strings of mucus from its mantle — a footlike
appendage hanging out of the tube’s opening — in slow motion, like some warped,
weirdo, saltwater version of Spider-Man. It releases the strings into the
current, forming a snotty web that it holds on to with its equivalent of a
toothy tongue, trapping plankton and other ocean debris. Then it reels in
whatever it has trapped, along with the snot.
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The openings of the tubes of the worm-snail are about as large as a pencil eraser. Once the tube is glued onto a hard surface, in this case the shell of a bivalve, the worm-snail stays for the rest of its life.
Rüdiger Bieler
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In a study published Wednesday
in PeerJ, scientists have identified this new species of worm-snail.
They’ve named it Thylacodes vandyensis after the General Hoyt S.
Vandenburg, a sunken, retired naval ship where tens of thousands of the snails
live. If they spread elsewhere, the worm-snails could damage the region’s
living coral.
The Vandy, as divers have nicknamed
it, is among a number of large, retired ships sunk in the Florida
Keys National Marine Sanctuary to provide new homes for ocean creatures
and alternative diving spots.
Researchers like Rüdiger Bieler,
a curator at the Field Museum in Chicago and the lead author of the
paper, monitor these artificial reefs to see what’s settling in. In 2014,
during two 20-minute dives, he and his colleagues found three of these
worm-snails. Now there are thousands.
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| The worm-snail produces webs of mucus to capture and collect food from the oceans. Rüdiger Bieler |
Dr. Bieler thinks the worm-snails
could indicate what kind of marine life is settling into the reefs. To make a
terrestrial comparison: “Are we getting the native butterflies back, or are we
just seeing feral cats?” he wonders. “It’s a new species, but we’re still not
100 percent sure where it’s coming from.”
The closest relatives of the
previously undescribed worm-snails are native to the Pacific Ocean. He
speculates that these mollusks stowed away on a ship before taking advantage of
the uninhabited artificial reefs: “There’s this brand-new real estate where
there are nonlocal species, few predators and very little competition.”
Monitoring these creatures on the
Vandy could help prevent their spread to natural reefs, where they could do
great damage. Similar worm-snails found in the Pacific and the Red Sea have
been found to slow coral reef recovery by killing coral tissue and
chasing off fish with a bioactive compound in their mucus.
“When you have them in the living
reef,” Dr. Bieler said, “there’s always this
kind of death zone around them.”