T HE tide was rising on Holiday Shore. As it covered the cobbles and the foot of the cliff, millions of little white shells opened to capture floating food.
There are millions of barnacles on the rocks of Holiday Shore.
The hungry creatures inside these shells were barnacles. Now, though barnacles have shells that open and shut, they are not related to clams. Strange as it may seem, their nearest relatives are crabs. When a barnacle is young, it swims in the water, just as a baby crab does.
If you dip water in a very fine net, you may catch some baby barnacles. At first they are tiny, colorless things floating about the bay. Naturally, many of them float into the mouths of hungry animals near shore; but as many live to grow up as there seems to be room for.
A very young barnacle has a three-cornered shell, one eye, and three pairs of jointed bristly legs. Growing older, he becomes oval in shape, while his shell has two halves like that of a clam. Next, the infant gets six pairs of feet, with which he swims rapidly in the bay. When the baby barnacle becomes tired, he rests on a rock. He holds himself to it by antennæ, or feelers, that grow from his small, round head.
As the barnacle grows, he becomes less and less active. Finally he settles headfirst on a rock and gives up swimming altogether.
When the barnacle next sheds his skin, he gets a new kind of cover. On it are two small shells that open upward. Around them are six little pieces that spread and fasten to the rock. They soon become hard plates of lime that protect the soft body inside.
In time the barnacle's shell becomes higher than it is wide. It is shaped somewhat like a tiny volcano with two lids for the opening at its top.
After the barnacle you see over there, for example, started to live with his head fastened to the rock, he could not, of course, use his legs for swimming. Instead, he spread them out like the parts of a fan which waved through the water and back into the shell. Hour after hour he kept his legs moving, bringing currents of water to the mouth inside the strong white shell.
The barnacles kept their legs moving hour after hour.
What did the barnacle get from the water? Many tiny bubbles of air to breathe, and food to eat. Exceedingly small plants and animals that floated near were the things he had for a meal. Baby clams, a starfish, and barnacles, that were so young they were drifting about in the water, were a part of his diet.
What else did he do? Very little. He could not go away for a swim, since his shell was tightly grown to the rock. Neither could he crawl into a cool damp crack when the tide went out. Of course, if he lived in a tide pool, it made no difference to him whether the tide was in or out, for there was always water in the pool and he simply kept on breathing and eating. But his neighbors who lived on the open rocks had to close their shells to hold the moisture inside until the tide returned. If rain fell between tides, these exposed barnacles had another reason for closing their shells. It was important to keep the rain out, for a dose of fresh water can kill most barnacles.
Children who visit tide pools in Quebec and England see barnacles of the same sort as those that may be found by millions covering the rocks of Holiday Shore.
The barnacles on rocks such as Holiday Cliff, where the tide leaves them uncovered for rather long times twice every day, do not live to be old. They die when they get to be two years old, and their shells break up and wash away. On some shores you will find white lime sand that is made of broken barnacle shells.
Those that live in deep water grow bigger, heavily wrinkled shells, and probably live several years.
Have you ever heard sailors tell about goose barnacles that fasten themselves to ships? They also live on wharf piles and rocks. If you take a boat along Holiday Cliff, you will find some of them on the point where waves roll in from the open ocean far beyond Holiday Bay.
Their name, goose barnacles, comes from a queer old legend. People once thought these barnacles grew on trees and hatched into tiny geese of some sort. In the year 1597 a man published a book in which he said that he had seen this happen!
Really, of course, goose barnacles live in the sea and their eggs hatch baby barnacles. Those babies swim and drift until they are old enough to settle down on their heads. But instead of fastening their shells to the rock, they grow long leathery stalks on top of which are their bodies and shells.
You will notice these stalks as soon as you see the barnacles. Some of them are four inches long, twisting and bending with every wave. The shells are smooth and bluish white, set in brown and orange flesh. As you watch, the legs spread out like jointed plumes to bring in currents of water holding air and food.
Goose barnacles put out their legs to catch food.
Because they can live on the bottoms of ships, goose barnacles travel all over the world. While traveling, they lay their eggs. The baby barnacles hatch, grow, and settle down wherever they happen to be. So it happens that goose barnacles like those on Holiday Point live on both shores of the Atlantic, Pacific, and Indian Oceans; in the Gulf of Mexico, and in the Mediterranean Sea.
Among the barnacles on Holiday Shore are many little creatures that live in tubes. Some of these tubes are slender and white, twisting about on clams or rocks. Other white tubes are coiled and shaped like shells of certain snails. These may be found on stones or clinging to seaweeds that grow in the bay and in sheltered tide pools.
Though they look so much like the houses of snails, these tiny shells really belong to worms. Put some of them in a dish of sea water and watch them through a magnifying glass if you wish to see the worms that live in them.
Tube worms in snail‑like shells, seen through magnifying glass.
You will need to wait a while, for these worms are timid, and at first their shells will be tightly closed by little plugs of hard flesh. But as soon as the water in the dish becomes quiet, and the worms get over the scare you gave them when you moved them, they will open their shells and begin to eat. First the plug is pushed out to one side; then you will see a ring of yellow or red plumes.
Those plumes really are the gills through which the worm breathes, but they also get his meals for him. Watch them as they bend and twist, sending currents of water with food into his mouth. Though the tube worm is not related to his barnacle neighbors, he eats in much the same way.
Worms that build the long twisted tubes are much larger than those with snail-shaped shells that stay on the seaweeds. Look in almost any tide pool; you will see their pretty red gills waving like feathers at the mouths of their shells. That is, you will if you are quiet enough. Otherwise every worm in the pool will pull itself back into its home.
When these tube worms were very, very young, they drifted in Holiday Bay as did so many others of the babies of the bay. Those of them that found their way settled down on the rocks of Holiday Shore, when they were old enough to do so.
There they began to make tubes of lime, fastened tightly to shells or stones. As they grew, they added more lime to their tubes, but they did not build them straight. So now their homes twist and coil, or even wind around one another. You might guess from their shapes that they belonged to wriggly worms, even if you could not see the builders.
The tubes of these worms twist and coil.