By Pat Garber
“Do you know what this is?” Ruth Fordan asked me one day recently, holding out her hand as we visited on my screened porch. “Danielle Creeksong found it at the edge of Pamlico Sound, and we thought you might recognize it.”
Ruth held a fragile, tube-shaped formation made of sand and covered with bits of seaweed and shell.
I studied it thoughtfully, trying to remember my marine biology, and said inconclusively that I thought it was some kind of tube worm casing. “Not sure, though,” I added.
A few days later, Creeksong, Ruth and I visited the sound side beach where the casing had been found to look for more.
We headed out at low tide and were soon intrigued by the discovery of a number of the odd, chimney-like casings, decorated with all kinds of marine debris. The tubes were plentiful, but we saw no signs of their inhabitants.
Determined to learn more, and after considerable searching, I received an answer from Terri Kirby Hathaway, marine education specialist at N.C. Sea Grant in Manteo.
They are, she explained, the burrows of plumed or ornate tube worms (Diapatra cuprea.) These fascinating organisms inhabit sand and mud flats along the coast from Massachusetts to Florida, building and living in their amazing tubes.
The worms themselves, which we did not see, grow up to a foot in length.
They are a species of polychaetes: elongated benthic (bottom-dwelling) creatures with segmented bodies. Multiple fleshy appendages known as parapodia grow on each segment, which is why they are often called bristle worms.
Plumed tubeworms have five long antennae, extremely large jaws, and bright red, bushy plume-like gills surrounding their heads.
According to a story in “Life in the Chesapeake Bay” (1984), it is one of the largest and most beautiful polychaete worms in the Chesapeake, (and probably in the Pamlico.) Another account describes them as resembling Christmas trees.
These worms secrete mucous which they use to cement sand and other bits of their environment together forming heavy, leathery tubes which may descend several feet under the sand and sometimes two to three inches above the surface.
They reside in these tubes, venturing out to capture plankton and to scavenge for detritus. They withdraw down inside when disturbed, so are seldom observed, but can occasionally be seen poking their brightly plumed heads out in search of prey.
They live in colonies, and are sometimes found in huge numbers. Their life cycle is something of a mystery, but it is believed that they spawn in surface waters in mass aggregations, possibly in response to moon phase or tide, water temperature, or amount of daylight.
Fertilization is external with eggs and sperm released into the water, probably at night.
While relatively common now, coastline erosion, development and climate change could reduce plumed tubeworm numbers in the future.
Watch for their vacant decorated tubes as you explore the shallows of Pamlico Sound, and keep your eyes open to spot their brightly plumed heads peeking out of a tube.
Earliest larval stage is called a trochophore.
They spend the first two months of their lives as plankton, floating through the water.
After one week, they begin building little tubes in which they float. Later they settle down on the sea floor.
Categories: Ocracoke's nature, flora & fauna