  Living things cover the face of the earth from the torrid sands of the desert to the cold wastes of the Arctic, and every variation in environment develops a closely knit community of plants and animals. They are the ones best adapted to living where they do, or they may have been the first to arrive there, filling all available homesites and monopolizing the food and water supply to create a “closed” community. In each environment, a delicate balance is established between its various residents and between them and their surroundings. The study of all these interrelationships is called “ecology.” Beginning with the environment, we have seen in our brief look at the origins of Castle Neck how drastically an area can be altered as conditions change on the earth’s surface. Environment is affected in other ways, too. Man’s activity can change it almost overnight as a bulldozer clears land for a housing development, a dam alters the flow or course of a river, or careless disposal of a cigarette or campfire lays waste to acres of woodland. Or, as in the slow development of a forest, the growth of the trees themselves can change the environment, the maturity of one species whose seedlings require sunlight contributing to the growth of those better adapted to shade. If you should watch an old abandoned pasture over a period of many years, you could see environment gradually altered. First there are the mosses and grasses that create a fertile soil. Then come the Poplars and shrubs. As these grow they offer shade where Pines and, finally, the broad-leaved trees can flourish. This change in vegetation will also bring about a change in the resident animal communities. When parts of Castle Neck were rich farmland, specialized forms of life which thrive in that type of environment were abundant there. We have only to look at Castle Hill, just a few hundred yards from the dunes, or at some of the swamps that dot the Neck to see how different are the inhabitants from those of the dunes. On the Hill live the Oaks, Maples, Jumping Mice, Raccoons, and Toads, plants and animals that would be misfits indeed—if they could live at all—in the world of moving sand. Maples and Oaks, relics of the time when the dune area was fertile, may still be found dying and being buried over by drifting sand. Now it is a different community of plants and animals living here. The continually shifting sand and the scarcity of water limit the variety of life found, but each dune dweller is specially adapted to this homesite, and no matter how lush, green, and more attractive a neighboring meadow may look to us, many of these specialized organisms could not survive there at all. It has taken millions of years for the long, slow process of evolution to develop specific adaptations that suit dune dwellers to their environment. There are variations between individuals in every form of life. Mostly these are normal inherited variations, such as height or color. But sometimes sudden variations, called “mutations,” occur through accidental changes in the genes controlling inheritance. These are new characteristics not found in other members of the same species. If the mutation is advantageous it may be passed on, and it is in this way that new life forms slowly develop. If the mutation allows a species to live more easily in its environment, it may displace some older form, which may then be unable to compete successfully for food, water, or shelter. Indeed, all life is engaged in a constant struggle for survival; it is those individuals and species best able to adapt to the changing conditions of their environment that endure. Think of the whole series of crises faced by any living thing in its lifetime, then of these crises being met and overcome in the seemingly inhospitable environment of the dunes. In the beginning, our dune dweller must be born, a difficult enough task without interference from unkind surroundings; it must feed itself, here in an area where meals would certainly seem at a premium; it must grow, oftentimes shedding its skin in the process; it must live not only in the summer’s heat but, if its life span is that long, in the winter’s cold; it must endure long periods of drought, flood, wind, and storm; and most important of all, it must survive long enough to reproduce its kind, or else it has missed its goal. But such is the wonder of nature’s specializations that our dune dwellers can usually meet these normal crises. Their adaptability and rate of reproduction safely insure the future of their kind, and their overpopulation, if left to nature, is delicately controlled by available food and shelter and their predators. Exploring the dunes and making the acquaintance of the inhabitants, you can see this environmental community meshing its lives together, and you can observe the fine degree of adaptation developed by each life form. You may find an occasional Apple tree growing out of the sand, rooted in a more fertile soil below, a reminder of the time when that bit of the Neck was a rich farmland. The roots of the Beach Plum also reach down to the water table, and it is thus able to grow out of the sand, although its seedlings cannot take root in the sand. Most of all, you will have an opportunity to note many special animal and plant peculiarities the dune dwellers have developed to suit their particular environment. SOME ANIMAL ADAPTATIONSA Nest Deep Down in the SandWalking through the dunes, you will frequently notice a small hole in the sand. Poke a blade of grass into it and you will find the hole quite deep. As a matter of fact, it may extend down two feet. This hole is made by the Sand No Nest at AllDozens of Common Terns are to be found nesting at the southern tip of the Neck. Long ago, the Common Tern began laying its eggs on the bare sand, and made no nest at all. Each egg is sand-colored, with speckles resembling pebbles. Only a patient search will locate a Tern nest on the Beach, and then, unless you are cautious, the discovery may come after you have accidentally stepped on the eggs. Eating What Comes to HandBayberries have a hard wax covering that makes them seem quite unpalatable to us, compared to the more succulent berries found away from the dunes. Yet here the Crows, Tree Swallows, and Myrtle Warblers are Bayberry-eaters. The Myrtle Warbler in particular derives most of its winter diet from Bayberries. In fact, its name comes from the scientific classification of the Bayberry, which is in the Wax Myrtle Family. The Art of Being InconspicuousThe sand offers few places of retreat and few for hiding. It is not surprising, then, that many of the living things here have a sand-colored protective coloration. There is a large Grasshopper, or Locust, commonly found on the Beach. Its dull, gray, speckled wing-covers make it practically invisible when at rest. But the underwings, used for flight, are a striking orange with black bands. When discovered, the Locust flies up, confusing its attacker with this bright flash of color and a loud whirring noise. Unlike most insects, this Locust eats the thick-skinned, dry Beach Grass. PLANT ADAPTATIONSAny plant that is adjusted to living in a region where there is a decided lack of water is called a “xerophyte.” There are many different ways in which plants have adapted their structure and way of life to the dune environment. For instance, to reduce water evaporation they may have a very small leaf, to Here are just a few common examples of xerophytes and other plant adaptations to be found at Crane’s Beach. Anchor for the DunesBeach Grass (Ammophila breviligulata) is a true xerophyte and has many sand-dwelling characteristics. Its grasslike blade is rolled in at the sides, oftentimes becoming a tube, in order to reduce the surface area. As you will probably discover, it has a pointed tip that can prick a finger and, as you may well imagine, acts as a deterrent to those who would eat or walk through it. Its underground stems, in true xerophyte fashion, extend over a large area in an attempt to gather all possible water, and these dense root-mats serve to anchor the dunes and prevent their migration. A Tough Sand DwellerThe Woolly Hudsonia (Hudsonia tomentosa) carpets the dunes, preferring its place in full sun to more shaded spots. The tiny leaves are awl-shaped and press very tightly against the stem, as though trying to hold in as much water as possible. Hudsonia is covered with a velvet-like down, which is less susceptible to evaporation than a smooth, large surface would be. An Adaptable MushroomSince mushrooms generally require plenty of water, you would not expect to find them at the beach. Several species, however, may be discovered here. The most readily identifiable is the Earth Star (Geaster hygrometricus), which resembles a Puff Ball but differs in having the outer layer of the skin divided into tough, star-shaped segments. During the dry seasons, this star is drawn up around the ball by its contraction, thus protecting it against further desiccation. In wet weather, the ball swells and holds the star against the ground to allow for water absorption. The “roots” of the Earth Star are shallow, so the plant may readily be dislodged. The wind easily blows it across the dunes, spreading the spores over a wide area. NOW IT’S UP TO YOUThere is something new to be known about every animal and plant. Now it’s up to you! Careful observation will allow you to discover many other examples of special adaptation to life in the shifting dunes, and the next chapters will introduce you to some of the more common of the living things inhabiting this strange sand-world. And if you wish to read more about ecology, try these books:
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