All who have access to the seashore have a wonderful opportunity to study the Invertebrates. The long stretches of sandy beach, the sections of shore covered with water-rolled pebbles and stones, even the steep, jagged cliffs, are all pebbled with these animals of the sea. Twice every twenty-four hours the sea water creeps slowly up the beach until high water is reached, and twice every twenty-four hours it recedes again toward the ocean. It is therefore about twelve hours from one low water to the next. On a gently sloping beach, the distances between the high water mark and the low water mark may be many hundreds of feet, while on a steep beach or a straight cliff this area may be only a few feet in width. It is this area between the high and low water marks that is the haunt of many Invertebrates. These are animals that can live if they are not continually covered with water. Here are the rock barnacles, the soft clams, crabs of many kinds, beach fleas, numerous sea worms in their special houses, snails, and hermit crabs. Others will be found in the pools between the rocks or in the crevices of the cliffs, which as the tide falls becomes great natural aquaria. Here will be found hydroids, sea-anemones, starfishes, sea-urchins, barnacles, mussels. In the shallow water, crabs and shrimps are crawling along the sandy bottom or are lying concealed in the mud, while schools of little fishes scoot across the pool. If a fine silk net is drawn through the water and then emptied into a glass dish a whole new world of creatures will be revealed—jellyfishes, ctenophores, hydroids, eggs of fish, tiny copepods, the larvae or young of sea-urchins, starfishes, or oysters. If an old wharf is near by, examine the posts supporting it. The pilings seem to be coated with a shaggy mass of seaweed. Scrape some of this off and put in a dish of water. Sea-spiders, starfishes, hydroids that look like moss, sea-anemones, many varieties of worms, mussels and crabs are all living here.
UNDER THE SEA BED
Marine Worms, Whelk, Pecten or Scallop and Periwinkle
Begin your study of these seashore animals with a stroll along the beach. Examine the windrows of seawrack or seaweed. Whole troops of sandhoppers rise ahead of you. Oftentimes animals from distant shores or deep water will be found. The empty shells have many a story to tell. The papery egg-cases of the periwinkle remind one of a beautiful necklace. The air bubbles rising from the sand or mud as the wave recedes mark the entrance to the burrows of worms. Stamp hard on the sand. A little fountain of water announces the abode of the soft clam. Watch the sand at the edges of the rippling water. The mole-crab may be seen scuttling to cover. In the little hollows between rocks a rock-crab or a green-crab may be found on guard.
WHELK (FULGUR CANALICULATA) AND EGG-CASES
Common Mollusk Found on Sandy Shores Along the Atlantic Coast of the United States.
For collecting in the pools and shallow water a fine-meshed net is desirable. Many of the animals can be caught and placed in glass dishes of sea water for close observation.
Group showing a starfish attacking an oyster; soft shelled clams; hermit crabs; fiddler crabs, etc.