warm waters of Palau, a small archipelago in the Pacific Ocean,
hold perhaps the richest and most biologically diverse coral reefs
on the planet. In this "cradle of diversity," marine biologists
have recorded 700 species of corals and 1,500 species of fish.
Palau's coral reefs began to grow millions of years ago when
coral polyps colonized submerged volcanic mountains. The tiny
polyps produced a material that cemented them in place. Side by
side, they built hard, external skeletons around their soft bodies,
and when they died, other corals built skeletons on top of them.
Geologic forces eventually raised the coral topped mountains above
the sea, and all the exposed corals died. In time, new colonies
built more reefs on the islands undersea slopes.
Today, divers swimming over the coral gardens of Ngemelis Island
are moved by nature's artistry and creativity. The top of this
reef, just a few feet below the surface, resembles wild flowers
swaying in the breeze. Here, soft coral trees and bushes seem
to have been painted in stunning shades of green, red, yellow,
Nestled among the Ngemelis corals are giant clams. These two-
or three-foot-long creatures, depicted in early movies as being
able to grab divers' feet, feed harmlessly on plankton-not divers.
And poking ever so slightly out of cracks in the corals are green
and red brittle stars. Related to sea stars, these animals grow
arms that break off easily if bitten by predators or touched by
scuba divers. Brittle stars hide until sundown, but at night they
crawl out, spread their arms, and feed on plankton.
Sometimes the best way to observe fish is to find a sandy patch,
settle down, and wait, letting them get accustomed to you. And
a good technique for finding a particular kind of fish is to look
from right to left, rather than left to right-the usual way in
which people view things. Looking in this manner slows down the
viewing process and increases the odds of sighting an animal.
One of the greatest underwater shows on earth can be seen at
Blue Corner, a part of the archipelago named for the deep blue
quality of its water. Here, currents strong enough to rip the
mask from a diver's face bring in a healthy supply of plankton,
a food source that attracts unicornfish, tangs, and other plankton-eaters.
In turn, these fish attract huge schools of predators, including
sharks and jacks. The school of jacks can number 300 or 400 and
be so dense that it nearly blocks the sunlight, creating the effect
of an underwater eclipse. Blue Corner also attracts manta rays
and eagle rays. With wingspans of several feet, these large plankton-feeders
have few predators and can feed leisurely without having to worry
about the ever present sharks patrolling the reef.
At Blue Corner, the currents are so fast that a diver's encounter
with a pelagic fish may last only a few minutes before he or she
is whisked into the open ocean. Some divers overcome the time
constraints of current diving by using a reef hook, a three-foot-long
line with a hook at both ends. One hook attaches to a scuba vest
and the other to a nook or cranny in the reef. The hook extends
the dive, but in the process of setting, adjusting, and releasing
it, a diver damages the fragile corals. Healthy coral gardens
are found in many other areas of Palau, but at Blue Corner major
areas of coral are now barren white patches of rock. This little
corner of the world shows what can happen when underwater wonders
are overwhelmed by people's desire to see them at any cost.
Palau's other attractions are 80 marine lakes. Jellyfish lake,
with its extraordinary jellyfish population, is the most visited.
Like the others, it is dark green, has poor visibility, and is
as warm as bathwater. Each day, jellyfish slowly follow the sun's
path across the lake, soaking up sunlight for the life-supporting
algae in their tissues. Because they haven't needed to protect
themselves from predators, these jellyfish have lost the ability
to sting. Their lake was sealed off from the open ocean eons ago,
and jellyfish-eaters, such as turtles, were locked out. Without
the threat of getting stung, today's underwater explorers can
swim freely among yellow polka-dotted jellyfish shimmering harmlessly
in the sun.