The arms bear numerous prehensile suckers, which grip the prey. In the mouth there are strong jaws shaped like a parrot's beak. The cuttlefishes are molluscs and may be regarded as the highest of the backboneless or Invertebrate animals. Many occur near shore, others in the open sea, and others in the great depths.] [Illustration: GREENLAND WHALE Showing the double blowhole or nostrils on the top of the head and the whalebone plates hanging down from the roof of the mouth.] [Illustration: MINUTE TRANSPARENT EARLY STAGE OF A SEA-CUCUMBER It swims in the open sea by means of girdles of microscopic cilia shown in the figure. After a period of free swimming and a remarkable metamorphosis, the animal settles down on the floor of the sea in relatively shallow water.] [Illustration: _Photo: British Museum (Natural History)_ AN INTRICATE COLONY OF OPEN-SEA ANIMALS (_Physophora Hydrostatica_) RELATED TO THE PORTUGUESE MAN-OF-WAR There is great division of labor in the colony. At the top are floating and swimming "persons"; the long ones below are offensive "persons" bearing batteries of stinging cells; in the middle zone there are nutritive, reproductive, and other "persons." The color of the colony is a fine translucent blue. Swimmers and bathers are often badly stung by this strange animal and its relatives.] [Illustration: A SCENE IN THE GREAT DEPTHS Showing a deep-sea fish of large gape, two feather-stars on the end of long stalks, a "sea-spider" (or Pycnogon) walking on lanky legs on the treacherous ooze, likewise a brittle-star, and some deep-sea corals.] The fauna of the shore is remarkably _representative_--from unicellular Protozoa to birds like the oyster-catcher and mammals like the seals. Almost all the great groups of animals have apparently served an apprenticeship in the shore-haunt, and since lessons learned for millions of years sink in and become organically enregistered, it is justifiable to look to the shore as a great school in which were gained racial qualities of endurance, patience, and alertness. II. THE OPEN SEA