AWAKING BEFORE DAWN, on a recent morning, I could hear the pulse of the ocean drifting over the dunes and through the walls of my house. The roar of the sea impaled me like a harpoon and pulled me to the shore as if I didn’t have any choice. On the ocean side of the dunes, a ghost crab peered from its burrow then melted back into the sand giving honor to its name. As I stepped out onto the open beach, I could feel the vibrations of the pounding waves coursing through the sand. The swells were undulating across the surface of the ocean like the ripples on a sail luffing in the wind. The sound was a constant mixture of individual crashing waves that meshed together like the white noise found on a sleep machine. Waves that traveled across a vast ocean, carried and now released the voice of a low pressure system well out to sea.
Storms are a beachcomber’s ally, a philanthropist depositing gifts and curiosities along a beach strewn with sea weed and chunks of airy foam. I rambled along the beach looking for the calcium carbonite trophies, of which there were a few. Some nice whelks and helmet shells would quickly be snatched up as soon as the sleepy tourist, sipping their coffee, began their morning at the edge of the sea. I resisted the urge to pick up shells, instead intent on finding the unusual. It didn’t take long as I double stepped to prevent myself from trampling on a dark golden colored disk shaped object complete with a blue boarder and tassels. But this was not a sea shell, or even an animal, it was a colony of animals.
This group of organisms, which is related to jellyfish, is known as a Blue Button. This object, which looks like it could be a colorful brooch pined to the lapel of a jacket, is a group of hydroid polyps that usually live well out to sea on the surface of the ocean. Each animal in the colony has a specific function such as reproduction, feeding or protection. The sturdy one and a half inch round disk is filled with gas which creates buoyancy. Trailing underneath the disk are numerous tentacle-like strands of hydroids. At the ends of the tentacles are powerful stinging cells called nematocysts. Inside each cell is a coiled harpoon-like spear that is launched when water pressure enters the cell. These spears are used as a deterrent to predators and to capture prey such as crab larvae. Lacking any form of propulsion, these animals wander the ocean at the pleasure of the wind, the waves and the currents.
As I continued my search for the unusual, not far from the blue button, I found another similar object partially buried in the sand. This purplish two inch fleshy looking item, called a sea pansy, resembled a mushroom or even the petal of a flower. It is a type of soft coral that is also a collection of individual organisms that work cooperatively at different tasks to benefit the group as a whole. The leaf-like body is connected to stalk called a peduncle. Unlike the blue button, the sea pansy’s live on the ocean floor and is anchored into the sand or mud by the peduncle. Even If uprooted by rough seas the peduncle can establish a new mooring once it settles back on the sand.
The fleshy body has a firm and rigid structure thanks to needle-like objects called spicules. On the upper side of the body are two kinds of polyps. One is an anemone-like polyp that feeds by trapping plankton in gooey mucus. The other polyp controls water that enters the body allowing it to inflate or deflate as necessary. If exposed at low tide, the sea pansy will deflate the body allowing it to be covered by sand and hidden from predators.
When exposed during the night, the sea pansy can also thwart predators by distracting them by putting on an amazing show of pulsing waves of green light. A green fluorescent protein along with an enzyme creates this bioluminescent activity when the body is touched or molested by an aggressive predator. Interestingly, the enzyme is known as a luciferase, from the word Lucifer, which means light bearer.
As I handled the sea pansy in the daylight I was unable to detect any display of the bioluminescence. Intently studying the creature, I was unaware of the serious beachcombers that were now scavenging the beach. I walked off the beach as a group of giddy surfers trotted into the surf, eager to quench their thirst with head high waves that ended a long drought of rideable waves.
The NC Coastal Federation, a charitable nonprofit organization, working to preserve our beautiful and productive North Carolina coast. Visit nccoast.org.
Sam Bland, NC Coastal Federation