Introduction - Adventure Guide to Aruba, Bonaire and Curacao - page 15

Sponges
Much of the color on Caribbean reefs is provided by sponges. These simple
multi-cellular animals are called Porifera , which means pore-bearing
and refers to the organism's many ostia (surface holes) and oscula (inter-
nal openings). Approximately 5,000 species of sponges have been identi-
fied world-wide.
Most sponges attach themselves to hard surfaces on the ocean floor where
they use their flagellum to capture tiny organic particles that are floating
in the water. Nutrients from these particles, as well as oxygen, are
absorbed, and wastes are filtered out.
A single sponge may be either male or female, as the situation requires.
Living young that resemble plankton are released through the hermaph-
rodites' outgoing oscula and attach themselves to a nearby surface. The
life span of a sponge ranges from a few months to 20 years, and each organ-
ism can regenerate from microscopic fragments of the original.
Sea sponges come in a rainbow of colors, various shapes, and all sizes.
Some resemble a vase, others look like a fan, while others take on the
appearance of a tulip. Under favorable conditions, sponges form gardens
that become a habitat for other sea creatures. These fragile environs are
easily destroyed by pollution, rising water temperatures, over-harvesting,
and human carelessness.
The Reef
Curaçao is surrounded by a gently sloping reef composed of magnificent
coral formations. Much of it is protected as an underwater park. Dozens of
colorful fish feed here, and observant divers often spot eels, lobsters, tur-
tles, and rays. While the reef drops off sharply, snorkelers may still see
brain coral, sponges, and sea fans at shallow depths.
Reef Report
Living coral reefs are built over millions of years by thousands
of tiny soft-bodied organisms called polyps.
The polyps attach themselves to sloping underwater land, and
their soft bodies generate an outer skeleton of calcium carbon-
ate (limestone), which accumulate into rock-like reefs.
Coral polyps feed at night on microscopic bits of plankton that
float in the water.
Polyps reproduce sexually and asexually, so a massive reef may
begin with a single animal.
Other organisms, such as mollusks and worms, contribute to
reefs by leaving their skeletons behind when they die.
Algae helps cement corals together with calcium and magne-
sium deposits.