Basic information on corals can be found on the
previous lesson. Most coral are a colony of corals, composed of
individual polyps. Individual polyps live in their own little structures within the
main frame of the other corals. Only corals of the same species share
colonies with other corals; although various species of corals can live very
close to each other. Some corals can be found as individual
polyps. Individual polyps usually have larger skeletons.
The information below corresponds to the samples
Life Cycle - Natural Environment (5A).
BLUE CORAL - Helipora species (blue colored specimen)
This Indo-Pacific blue coral, Heliopora, is relatively
rare. It has a massive lobed skeleton dissected by cylindrical
canals. The blue tint of the skeleton is masked in life by the brown
polyps, and is due to the presence of iron salts. It is used in jewelry
because of its color.
CLASS ALCYONARIA = Octocorals
BLACK SEA FAN - Order Gorgacea (black delicate fan structure)
The main stem is firmly attached to a hard surface by a plate
or a tuft of creeping branches. The stems contain a central strengthening
rod, consisting of a horny material (gorgonin). The short polyps occur all
over the branches of the colony being absent only on the main stem.
RED ORGAN PIPE CORAL - Tubipora species (red specimen)
The common name is derived from the parallel rows of tubes
making up the calcareous skeleton of the colony. When the polyps are
expanded, the red skeleton may be completely obscured. Colonies can reach
30 cm or more in diameter. Found in the Indo-Pacific.
CLASS ZOANTHARIA = Hexacorals
STAGHORN CORAL - Acorpora species (white, long straight specimen)
Another of the fast growing reef builders, staghorn coral forms
thickets, sometimes of great size, with a lattice-work of loosely connected
branching coral colonies. Colonies may be yellow, brown or cream color
with white tips (where the growth takes place).
Staghorn thickets are found not often seaward of the reef flat, where they
may adorn the tops of buttresses at moderate depths. They are also found
forming patch reefs in protected lagoons and shore zones in shallow water
connected to other colonies (if at all), and are encrusted with algae, sponges,
and tunicates. Damselfishes frequently stake out their territories in
staghorn as well as elkhorn coral.
ELKHORN CORAL - Acorpora species (creamy white, smoother specimen that look
like a reindeer's horn)
The fast growing branching colonies of this coral are sometimes
4 meters or more across. The flattened (or thick and cylindrical) branches
are brown to yellow with white tips The white tips are due to lack of
symbiotic algae, the zooxanthellae, in areas of new growth.
Elkhorn coral competes by growing rapidly and by shading or over-topping its
neighbors. It often dominates shallow fore reef zones on windward,
wave-swept shores. It is sometimes toppled by storm surf, but may re-grow
from its new positions (broken fragments regenerate to form new
colonies). This capability may partially explain its wide
BRANCHING, BRUSH, OR BROWN STEM CORAL - Madracis (specimen with brown spots
with branching tips)
These yellow to cream-colored colonies may be
several meters across and are formed of thin delicate branches packed tightly
together. The more massive colonies form gently rounded mounts.
This coral is found at moderate depths on
buttress tops, flanks, and fore reef slopes. Brittle stars and other
invertebrates are often harbored between the branches. Inner parts of the
branches are dead and are encrusted with algae, sponges, and other attached
invertebrates. The brittle branches of the coral are easily damaged by
divers and boat anchors.
POCA CORAL - Montipora species white, small polyps, crinkled, some have
small red specks on them.
Poca forms flat, leafy colonies which may reach 2 meters or
more across. It often grows in dense masses over reef slopes in the
MUSHROOM CORAL - Fungia species (individual polyp, circular specimen
with large septa).
A common species reaching 20 cm in diameter,
which is found on reefs and lagoons in the Indo-Pacific. As adults, all
species are free-living, but when young they are often seen in clumps, each
polyp attached to the bottom by a stalk.
FLOWER CORAL - Eusmilia species (white, large polyps that give the
appearance of being squished).
The branching colonies of this coral are
brown, green, or yellow and have one large polyp at the top of each
branch. Colonies form mounds which may be 1 meter or more across.
The polyps are generally retracted during the
day, but extend long transparent tentacles for feeding on plankton at night.
LEAF CORAL - Montipora species (slightly
green, small holes, flatten).
Leaf corals form flat, leafy colonies which
may reach 2 meters or more across. They often grow in dense masses over
reef slopes in the Indo-Pacific.
- Discuss the different corals that you
have. The names are not as important as observing the different characteristics
of the corals. Use the information in the "Background" section
to guide your lecture.
- Give students a package of corals. Provide hand
lenses or Swift-GH microscopes to observe the corals in detail. Students
should draw what they see on their lab sheets. You might want to
help students draw the individual polyps by going over the following art
|to make a stem
||draw disc shape
|fill in lines
- There may be more than 4 different types of corals that
the students have. If they want to draw more, use the back of the
lab sheet. After they finish drawing their specimens, see if they
can match their specimens with the display materials.
- Emphasize with students that there are many types of
corals, each with its own characteristics. Make sure students realize
that corals belong to the Animal Kingdom, and that they are invertebrates.