Every plant, every animal, every physical element is involved in this web of life—as soil builder, predator, plant-eater, scavenger, agent of decay, or converter of energy and raw materials into food. Damage to or removal of any of these components—pollution of the water, lowering of the water table, elimination of a predator, or any interference in the energy cycle—could destroy the glades as we know them. [Illustration: BEGINNING OF FOOD CHAIN] ALGAE AND ONE-CELLED ANIMALS INVERTEBRATE LARVAE PERIPHYTON MASS SAWGRASS SAWGRASS DIES AND MAKES PEAT Every other plant-and-animal community in the park—hammock, mangrove swamp, pineland, etc.—is an association of large and small organisms sharing a physical environment. It is impossible to understand either the park as a whole or the life of a single creature without being aware of these interrelationships. Alligator Hole in the Glades Out in the sunny glades the broad leaves of the alligator flag mark the location of an alligator hole. This is the most incredible ecosystem of all the worlds within the world of the park; for in a sense the alligator is the keeper of the everglades. With feet and snout these reptiles clear out the vegetation and muck from the larger holes in the limestone. In the dry season, when the floor of the glades checks in the sun, these holes are oases. Then large numbers of fish, turtles, snails, and other fresh-water animals take refuge in the holes, moving right in with the alligators. Enough of these water-dependent creatures thus survive the drought to repopulate the glades when the rains return. Birds and mammals join the migration of the everglades animal kingdom to the alligator holes, feed upon the concentrated life in them—and in turn occasionally become food for their alligator hosts. [Illustration: ALLIGATOR FLAG] Lily pads float on the surface. Around the edges arrowleaf, cattails, and other emergent plants grow. Behind them on higher muckland, much of which is created by the alligators as they pile up plant debris, stand ferns, wildflowers, and swamp trees. Algae thrive in the water. The rooted water plants might become so dense as to hinder the movement and growth of the fish, were it not for the weeding activities of the alligators. With the old reptiles keeping the pool open, the fish thrive, and alligator and guests live well. Plants piled beside the hole by the alligator decay and form soil with mud and marl. Ferns, wildflowers, and tree seedlings take root, and eventually the alligator hole may be the center of a tree island.