Threads from the Web of Life: Stories in Natural History

Stories in the Sand

3 Stories in the Sand THE coral heads pack the reef like a field of boulders between which no level ground shows. Every niche is filled—shelves of coral extend from the reef’s outer walls, branching fan corals rise from the gaps between crowns of cauliflower corals and skull corals, one growing on another. In the continual competition for space, the faster-growing corals bury the slower beneath them, eventually compressing their forbears into limestone, raising the reef on the skeletal remains of previous coral generations. One patch of white sea floor stands alone as the sole flat spot in this stone garden. There is no sand between the coral heads here—close inspection reveals the white patch to be a mélange of skeletal remains: curved pieces of worn seashell, broken shards of bleached coral, bits of bone. Every fragment retains a trace of its original character—an edge of blue, a pearly surface—just enough to attest to the life-span of growth and prosperity won from the ocean by the maker of each—all against very long odds. This rare, white landing pad is the site of a cleaning station. The coral masonry at its edges shelters a family of Blue-streak Wrasses, diminutive fish only a few inches long, slow swimmers with yellow head colors grading along their length to neon blue, and a lateral black band widening toward the tail. Their signal coloration is invitation to the main fish of the reef to come in and be freed of their parasites, which for the wrasses are food. Above the flat, sand-white surface, a Blue Jack hangs motionless , gaping as if about to strike. The jack’s silver scales shimmer with iridescence, reflecting its perfect health, maintained by daily visits to this cleaning station. The diminutive wrasses flit about its head and gills, pecking here and there, eating the tiny lice and 4 Threads from the Web of Life isopods that would grow and multiply to torment this fish if not removed. The whole tableau of jack and orbiting wrasses is framed in the gape of a huge tarpon suspended in mid-water just behind the scene. The motionless predator appears frozen at the instant of attack, her smaller prey fallen in the shadow of her yawning jaws for their one last instant. With the exception of the wrasses, all these sleek reef fish are piscivores—they all eat each other, the bigger growing at the expense of the smaller. But the fish in the foreground at the cleaning station feel no pressure wave building in the water, no indication of the gathering momentum of a strike in their direction. The tarpon drifts in the background, marking time, her mouth hanging open merely to signal that she is waiting in line for her turn with the cleaning fish. SIXTY feet down in the twilit depths of the reef’s outer wall, a Black Grouper hangs suspended, staring out through the opening of a dark coral cave. A spinal stiffening has beset this big sea bass, resulting from an infection taking longer than usual to cure itself. Ordinarily the master of the reef, this fish has not been abroad in the open water for many days. The struggle for survival has guided this grouper through a lifetime of deadly risks, leading ultimately to a position of dominance on this reef. She began life decades ago, tumbling in the wake of a huge Basking Shark that was trolling across the surface just where she hatched from a floating egg. The shark’s wide-open maw sucked most of her siblings out of the water beside her. Of the few other fry that survived, most lasted only long enough to encounter a wild variety of similar fates: they were speared by sea birds, stung by invisible threads and raised paralyzed toward the diaphanous bells of jellyfish, snapped up by bigger bass; 99 percent of her generation did not survive their first year. She was lucky enough to catch many a smaller meal but never to be caught herself while she drifted across the ocean. When she reached the shelter of this coral oasis, she quickly learned the strategy of seeking the easy prey—those that, through age or injury, had lost that supple flick of the tail that could keep them ahead of her attack.  Threads from the Web of Life As she glided through...