NATURE NOTES FROM ACADIA

THE ACORN SHELL

Incrusting the rocks along much of the ocean front of Mount Desert Island lives the Acorn-shell or barnacle, an odd kind of marine crustacean. In places the rocks which meet the beating surf support so dense a coating of these animals that their aggregate resembles some enormous gray plasmodium creeping out of the sea and sending its arms wherever the spray dictates. The tide pools often contain lesser numbers of individuals and it is here that these animals in their little crater-like dwellings can be studied to best advantage. The stretch of rock-bound seashore between the Sand Beach and Otter Cliff, an area within the boundaries of Acadia National Park and only a short distance from Bar Harbor, is an excellent region wherein one can find the interesting Acorn-shell at home.

Until about a century ago the barnacle was believed to be a kind of mollusk - a sort of cousin to the clam and the oyster. After its unique life-history had been studied, however, it came to be classed with the crustacea or crab-like animals, a group to which it really belongs.

Upon hatching from the egg the young barnacle, called a nauplius, is free-swimming and bears no resemblance to the adult. In size it is almost microscopic. After swimming about and undergoing several moults it attaches itself by means of modified antennae to some rock or other object which becomes its permanent home. The barnacle then undergoes a metamorphosis during which time it attains its curled plume-like legs and a new shell. No food is taken in during this period of transformation to the adult form. Later its food consists of such minute animals as teem in the sea water. These are drawn into the mouth by a current created by a motion of the plume-like legs. Huxley described a barnacle as "a crustacean fixed by its head and kicking the food into its mouth by its legs."

This animal is sometimes called the "sea-acorn." The calcareous little crater is made up of six plates while the lid consists of four plates. In places they cover the rocks to high water mark in such profusion that one can readily understand that existence of the individuals is governed to a large extent by the availability of a suitable anchorage place. Attaching themselves as they do to sailing vessels, the barnacles become of eoonomic significance. A few years ago it was estimated that these animals result in a total waste of about one hundred million dollars a year to shipping interests. Most of this amount was for such quantities of additional fuel as were needed in order to offset the retarding influence of the vessels' greater or less coating of barnacles.

- Ranger Naturalist

Throughout the month of July, yellow is probably the dominating wildflower color on Mount Desert Island. St. John's Wort, Evening Primrose, Buttercups, Yellow Hawkweed, and early Goldenrods grow in profusion along the roadsides while Swamp Candles, Sundrops, Whorled Loosestrife, Yellow Pond Lily, Bladderwort, and others are to be found in localized habitats.

White seems to be second only to yellow as the most conspicuous of July flower colors. Daisies, Meadow Sweet, Meadow Rue, Pearly Everlasting, Common Elder, and Three-toothed Cinquefoil are abundant while Yarrow, Shin Leaf, Arrow Leaf, and Mountain Sandwort add their bit to the white floral display.

Pink, lavender, and purple flowers include some of the most beautiful of July wild plants. Fireweed, Wild Roses, Sheep Laurel, Purple Loosestrife, Rose Pogonia, Steeplebush, Purple-fringed Orchid and Thistles are in full bloom during the month.

Those who have climbed to the rocky summit of The Flying Squadron during July must have heard the singing of White-throated Sparrows, Juncos, and Northern Yellowthroats while on this mountain top. The wheezy high-pitched notes of Cedar Waxwings are also to be expected there. The Hermit Thrush, without much doubt our finest wild songster, is often heard far down on the mountain side. Since July is so lacking in bird songs the above few are doubly welcome.

A number of common Garter Snakes, mostly young individuals, have been seen in the park. These and the Milk Snakes appear to be the largest and commonest snakes here. The Grass Snake and the Red-bellied Snake, being more secretive in habit, are seldom seen but are sometimes found under stones, boards, and loose bark of old fallen trees.