Guide to Coral Reefs

from
Gulf of Mexico
What are corals?
A coral colony is built by groups of tiny animals called polyps. These polyps produce a skeleton called corallite.
The polyps grow and produce more of themselves to increase the overall size of the coral colony. This is a slow
process, and many coral species only grow ¼ to ¾ inches per year.
Many corals get their color from algae that lives in their tissues.These algae provide corals with energy during
the day through photosynthesis so, water clarity plays a vital role in coral growth. At night, corals extend their
tentacles and use their stinging cells to catch food from the water column.
Coral colonies can grow in many shapes depending on the amount of light and wave action on the reef. For
example, corals in deeper waters tend to grow in a wide, flat shape to capture more light. Reefs closer to the
surface tend to have more branching corals that can withstand wave action without breaking.
Endangered Species Act
Special protections have been given to seven hard coral species in the Gulf of Mexico. Elkhorn coral, staghorn
coral, pillar coral, boulder star coral, mountainous star coral, lobed star coral, and cactus coral are listed as
threatened under the Endangered Species Act. This means that they are likely to become in danger of extinc-
tion in the near future. The listing as threatened on the Endangered Species Act promotes the development
of strategies to protect these listed species and ecosystems and is an important tool for the conservation of
corals.
This guide can be used to identify the seven species of threatened corals (orange band on the page), 15 other
species of hard corals (blue band on the page) , and 1 species of fire coral commonly found in shallow waters
of the Gulf of Mexico. There are many more types of corals in the Gulf and you can follow the web sites in the
back of this guide for more information.
Elkhorn Coral
Locations: Elkhorn corals (Acropora palmata)
can be found throughout, the Bahamas, Florida,
and the Caribbean. Lives in high-energy zones,
with a lot of wave action.
Depth: 1 - 55 feet, most common between 1 - 35
feet.
Color: Golden tan or pale brown with white tips.
Shape: Colonies have branches that resemble
moose horns and stem out of a central trunk.
The surface is covered by protruding tubular
cups called corallites, built by the individual coral
polyps.
Size: Individual colonies can grow
to at least 6 feet in height and 12
feet in diameter, with a branch
diameter around 2 - 10 inches.
Staghorn Coral
Locations: Staghorn corals (Acropora cervicornis)
can be found throughout the Bahamas, Florida,
and the Caribbean. They can grow on a variety
of reef habitats, such as patch reef, spur and
grooves, and other types of hard bottom.
Depth: 15 - 60 feet.
Color: Brown to yellow-brown in color, with
white tips.
Shape: Colonies have antler-like branches that
stem out of a central trunk. The surface is
covered by protruding tubular cups with
individual polyps.
Size: Under optimum conditions
these corals can grow 5 - 6 inches
in branch length per year.
Colonies can grow to be 4 feet
tall and 6 feet wide.
Pillar Coral
Locations: Pillar corals (Dendrogyra cylindrus)
can be found throughout the Bahamas and the
Caribbean, but its numbers have been declining
in Florida. The colonies can grow on flat or slop-
ing hard or sandy bottoms.
Depth: 4 - 65 feet.
Color: Light tan to golden brown.
Shape: Colonies build tall columns or large
finger-like structures that grow upward from
the base. It is one of the few hard-coral species
whose polyps extend out for feeding during
the day. The extended polyps give the colony a
fuzzy, hair-like appearance.
Size: The cylindrical columns of
the colonies can reach up to 10
feet in height.
Mountainous Star Coral
Locations: Mountainous star corals (Orbicella
faveolata) can be found throughout the Gulf of
Mexico, Flower Garden Banks, Florida, the Ba-
hamas and the Caribbean. They can be found in
most reef environments.
Depth: 6 - 130 feet.
Color: Color can vary in shades of yellow-green,
pale-brown, and grey.
Shape: Colonies can form massive structures
that look like a skirt on the reef. Colonies have
cone-like bumps on the surface that are usually
arranged in vertical rows like mountain
chains, hence the name “mountain-
ous star coral”. Colonies in reefs
deeper than 80 feet often have a
flatter shape.
Size: Colonies can grow up to
10 feet tall.
Lobed Star Coral
Locations: Lobed star corals (Orbicella annularis)
can be found throughout the Gulf of Mexico,
Flower Garden Banks, Florida, the Bahamas and
the Caribbean. They can be found in most reef
and evironments, and are often a dominant
component of Caribbean mesophotic reefs
(typically deeper than 100 feet).
Depth: 3 - 270 feet, most common between 3 - 33
feet.
Color: Color can vary in shades of yellow-green,
light-brown, and grey.
Shape: Colonies form a cluster of columns or
heads, with dome-like tops. The shape
can vary based on the light condi-
tions on the reef. For example,
colonies in deeper water make
flatter formations.
Size: Colonies can grow to be
up to 10 feet tall.
Boulder Star Coral
Locations: Boulder star corals (Orbicella franksi)
can be found throughout the Gulf of Mexico,
Flower Garden Banks, Florida, the Bahamas and
the Caribbean. They can be found in most reef
environments, and are often a dominant
component of Caribbean mesophotic reefs
(typically deeper than 100 feet).
Depth: 15 - 160 feet.
Color: Orange-brown, greenish-brown or
grayish-brown, often have pale or white bumps.
Shape: Colonies grow in a mound shape, with a
rough surface scattered with irregular bumps. In
deeper waters, colonies can grow in the shape of
flattened plates that stack on top
of each other.
Size: Reported to be the slowest
growing of the three species of
Orbicella corals. Colony diam-
eter can extend up to 17 feet
with a height of up to 6 feet.
Rough Cactus Coral
Locations: Rough cactus corals (Mycetophyllia
ferox) occur in Florida, the Bahamas, and through-
out the Caribbean, but it has not been reported
in the Flower Garden Banks (Gulf of Mexico) or
in Bermuda. They are more common in caves or
under ledges.
Depth: 15 - 270 feet.
Color: They are typically shades of grey or
brown, but may also be reddish or green.
Shape: Colonies grow as thick, encrusting plates
with valleys and ridges. The ridges are usually
lighter in color, and the coral polyps can extend
their tentacles during the day. Colonies
generally grow encrusting
formations or create overhangs
on the edges.
Size: Colonies will grow to 1 to
2 feet in diameter.
Great Star Coral
Locations: Great star corals (Montastraea
cavernosa) are abundant throughout the Gulf of
Mexico, Florida, the Bahamas, the Caribbean, and
other reefs of the western Atlantic. They can be
found in most reef environments.
Depth: 6 - 300 feet but predominate at depths
between 40 - 100 feet.
Color: Often green, brown, or reddish orange.
Shape: Colonies grow in mounds or domes,
although it can grow in plate-form in deeper
waters. Some variations expand their polyps dur-
ing both day and night.
Size: Colonies can grow up to 8 feet
tall. Individual polyps of this spe-
cies are larger in size (diameter
from ¼ to ½ inch), making them
easily identifiable due to be-
ing comparatively larger in size
than other corals.
Blushing Star Coral
Locations: Blushing star corals (Stephanocoenia
intersepta) are widely distributed in most reef
environments throughout the Gulf of Mexico,
the Caribbean, and the Bahamas.
Depth: 10 - 130 feet.
Color: Cream, tan, grey, or brown.
Shape: Blushing star coral colonies form
mounds. The base color of the colony is light
with circular polyps that have a dark rim. The
space between the polyps may be relatively
wide, and the tentacles can extend during day-
light. The name blushing star coral, comes
from the fact that upon disturbance,
the polyps retract and expose the
paler tissue, which makes it ap-
pear that the coral is blushing.
Size: Colonies can grow to 2 ½
feet tall.
Mustard Hill Coral
Locations: Mustard hill corals (Porites asteroides)
are found in the Gulf of Mexico, Flower Garden
Banks, Florida, the Bahamas, the Caribbean, and
parts of South America and western Africa.
Depth: 3 - 160 feet.
Color: Usually yellow, green, and grey to light
brown.
Shape: Colonies grow on top of existing
structure and encrust the surface. They are
smaller in shallow reefs, but can form massive
mounds in deeper waters. The surface is lumpy
and the corallites are close together
giving the colony a porous appear-
ance.
Size: Colonies can grow to 2
feet tall.
Branched Finger Coral
Locations: Branched finger corals (Porites
porites furcata ) are found in the Gulf of Mexico,
Flower Garden Banks, Florida, the Bahamas,
and the Caribbean. They can be found in most
reef environments, predominantly in shallower
waters.
Depth: 3 - 160 feet.
Color: Beige, brown, grey, can have purple
overtones.
Shape: Colonies form finger-like branches with
rounded tips and can form large beds. Polyps are
usually extended during the day, which
gives them a fuzzy appearance.
Size: Colonies are around 1 - 4
feet, and its branches can grow
to be ¼ to ¾ inch in diameter.
Symmetrical Brain Coral
Locations: Symmetrical brain coral (Pseudodip-
loria strigosa) colonies are abundand in the Gulf
of Mexico, Flower Garden Banks, Florida, the
Bahamas and Caribbean. They can be found in
most reef environments.
Depth: 3 - 130 feet.
Color: Green to brown, yellow-brown, or grey.
The valleys are usually lighter in color than the
ridges.
Shape: This type of brain coral has long and
narrow meandering valleys (narrower valleys
than Boulder Brain Coral). Colonies usually
grow in smooth, round mounds,
although some can be encrusting.
Size: Colonies can grow up to 6
feet in height.
Boulder Brain Coral
Locations: Boulder brain corals (Colpophyllia na-
tans) colonies are found throughout the Caribbe-
an, the Bahamas, Florida and the Gulf of Mexico,
including the Flower Garden Banks. They inhabit
most reef environments.
Depth: 2 - 175 feet.
Color: Typically, the valleys are green, tan or
white, with darker tan-brown ridges.
Shape: This is a massive brain-like coral that
forms rounded domes, although some colonies
can encrust or form rounded plates. Their polyps
form ridges and valleys on the surface, which give
its brain-like appearance. The valleys are wider
(up to ¾ inch wide) compared to other
brain corals (such as the Symmetri-
cal). The tops of the ridges have
a very thin line that divides the
ridges as it slants into the valley.
Size: Colonies can grow upto 7
feet height.
Massive Starlet Coral
Locations: Massive starlet corals (Siderastrea
siderea) are found throughout the Caribbean,
the Bahamas, Bermuda, Florida and the Gulf of
Mexico, including the Flower Garden Banks. In
shallow waters, colonies prefer areas protected
from wave action.
Depth: 2 - 220 feet.
Color: Uniform rusty-brown, light grey, or
golden-brown.
Shape: Colonies form round boulders, although
young colonies begin encrusting. Corallites are
sunk in and darker than the surface of the
colony.
Size: Can grow up to 6 feet in
height.
Lesser Starlet Coral
Locations: Lesser starlet coral (Siderastrea
radians) colonies are found throughout the Carib-
bean, the Bahamas, Bermuda, Florida and the Gulf
of Mexico, including the Flower Garden Banks.
Lesser starlet corals prefer shallow reefs, and can
tolerate living in environments with surge, silty
conditions, and temperature fluctuations.
Depth: 1 – 90 feet, although rarely below 30 feet.
deep.
Color: Whitish to light gray or light tan.
Shape: This species is different than Massive Star-
let coral because they do not form large colonies
and usually grow as encrusting plates. The
individual polyps are darker than the
rest of the colony and have a
star-like appearance.
Size: Colonies are relatively
small with a maximum width up
to 12 inches .
Elliptical Star Coral
Locations: Elliptical star corals (Dichocoenia
stokesii), or pineapple coral, are found through-
out the Caribbean, the Bahamas, Bermuda,
Florida, and the Gulf of Mexico. Colonies inhabit
the front, back, and base of the reef, but are
rarely found on the crest. They also inhabit outer
reef channels and lagoons.
Depth: 12 - 230 feet, but typically found in shal-
lower depths of 16 - 65 feet.
Color: Color variations are cream, yellow and
brown.
Shape: Colony are small and rounded with
elliptical corallites, although some can
form flattened plates. In deeper
water the plates tend to have
rounded corallites.
Size: Colonies can grow to be
1.5 feet in height and diameter.
Robust Ivory Tree Coral
Locations: Robust ivory tree corals (Oculina
robusta) are abundant in West Florida, but
absent in East Florida, the Bahamas and the
Caribbean. Colonies inhabit shallow areas with a
high sedimentation, such as turtle grass beds
(Thalassia testudinum). They are rarely found on
clear-water reefs.
Depth: 20 - 85 feet.
Color: Mustard yellow to yellowish brown.
Shape: Colonies from tree-like structures, with
a thick base and narrower branches. Corallites
protrude from the colony.
Size: Colonies can grow up to
30 inches. Branches can have a
diameter of up to 3 inches.
Ivory Bush Coral
Locations: Ivory tree coral (Oculina varicosa),
or ivory bush coral, is commonly found in the
Caribbean, Bermuda, the Bahamas, Florida, and
the Gulf of Mexico, including the Flower Garden
Banks. Although this coral can be found in the Ca-
ribbean, distribution is sparse with limited popula-
tions in the West Indies. It is common in turbid
waters and can tolerate large shifts in salinity and
temperature.
Depth: 3 - 75 feet.
Color: Yellow-brown. It can survive without zoo-
xanthellae and, in this case, would appear white
or pale.
Shape: Colonies are tree-like with nar-
row branches that tend to be short
and bent. Polyp tentacles are usu-
ally extended during the day.
Size: Colonies can grow to 12
inches, and its branches can
reach ½ inch in diameter.
Yellow Pencil Coral
Locations: Yellow pencil corals (Madracis
mirabilis a.k.a. Madracis auretenra) are distrib-
uted throughout the Caribbean, Florida, the Gulf
of Mexico, the Bahamas, and Bermuda. Colonies
are more common in deeper reefs, than shallow
reefs.
Depth: 3 - 190 feet.
Color: Pale yellow.
Shape: Colonies have many densely-packed
pencil-sized fingers (branches) with blunt tips.
Pale polyps are usually extended during daytime
and nighttime.
Size: Colonies can grow to 4 feet,
with a branch diameter of 1/4 to
3/ inches.
8
Ten-Ray Star Coral
Locations: Ten-ray star coral (Madracis decatis)
colonies are found throughout the Caribbean,
south Florida, the Bahamas, Bermuda, and the
Gulf of Mexico, including the Flower Garden
Banks. Colonies tend to grow on overhangs and
vertical surfaces.
Depth: 5 - 130 feet.
Color: Green, greenish-brown, yellow-brown,
violet-brown, tan, or grey.
Shape: Colonies can grow as encrusting coral or
with short lobes or knobs, Corallites are raised
from the colony skeleton.
Size: Colonies can grow to 6
inches with lobes that are 1 inch
in diameter.
Lettuce Coral
Locations: Lettuce coral (Agaricia agaricites)
colonies are distributed throughout the
Caribbean, Florida, the Bahamas, the Gulf of
Mexico, including the Flower Garden Banks, and
parts of South America. They inhabit most reef
environments.
Depth: 3 - 240 feet.
Color: Tan, yellow-brown, grayish brown,
purple, or blueish.
Shape: Colonies can grow in several forms
including encrusting sheets, thick lettuce-like
leaves, and flattened plates that can be
horizontal or upright. Colonies usu-
ally begin growth as an encrusting
plate, and leaves and vertical
projections become clear from
an early age.
Size: Colonies can reach 3 feet.
Fragile Saucer Coral
Locations: Fragile saucer corals (Agaricia
fragilis) are found in the Caribbean, the Gulf of
Mexico, including the Flower Garden Banks,
Florida, the Bahamas, and parts of South
America. They are more common in deeper wa-
ters, under ledges, and along walls.
Depth: 20 - 180 feet.
Color: Purplish brown, chocolate brown,
yellow-brown, or greenish tan.
Shape: Colonies are small, thin, and saucer-like.
The polyp corallites are small and arranged in
circles that share the same center, and
radiate outwards from the center of
the colony.
Size: Colonies can grow to 4 - 6
inches in diameter.
Branching Fire Coral
Locations: Branching fire corals (Millepora
alcicornis) are found in the Caribbean, the Gulf
of Mexico, Bermuda, and along the coast from
Florida down to Brazil. This the most common
species of fire coral in the Gulf of Mexico.
Depth: 3 - 130 feet.
Color: Tan to mustard yellow.
Shape: Branching fire corals are slender and
have tree like branching segments with cylindri-
cal features. The surface is smooth and covered
with minute pores within which the polyps live.
When the tiny polyps protrude, they appear as
short, fine hairs. It can encrust on hard-
bottom and on octocorals.
Size: Can grow to 18 inches tall.
Caution: Skin contact with this
organism will produce intense
stings, with some redness and
rash.
 Record Your Coral Observations
Species Date & Location Observations
A. Blushing Star Coral
B. Boulder Brain Coral
C. Boulder Star Coral*
D. Branched Finger Coral
E. Branching Fire Coral
F. Elkhorn Coral*
G. Elliptical Star Coral
H. Fragile Saucer Coral
I. Great Star Coral
J. Ivory Tree Coral
K. Lesser Starlet Coral
L. Lettuce Coral
M. Lobed Star Coral*
N. Massive Starlet Coral
O. Mountainous Star Coral*
P. Mustard Hill Coral
Q. Pillar Coral*
R. Robust Ivory Tree Coral
S. Rough Cactus Coral*
T. Staghorn Coral*
U. Symmetrical Brain coral
V. Ten-ray Star Coral
W. Yellow Pencil Coral
Why are corals important? • Become an informed consumer and
• Corals are an important source of food and habitat to many marine learn how your daily choices such as
organisms. water use, recycling, seafood, vacation spots,
• Coral reefs form a natural barrier that protects the coastline from fertilizer use, and driving times can positively
storm surge. (or negatively) impact the health of coral reefs.
• Coral reefs play an important cultural and economical role by sup-
porting jobs and businesses affiliated to fishing practices, tourism, • Be a marine crusader, in addition to picking up
and recreation. your own trash, volunteer in local beach or reef
What are the threats to corals? cleanups. If you don’t live near the coast,
Coral reefs are slow growing organisms, and their function and get involved in protecting your watershed.
well-being is threatened by a variety of stressors. Their stressors
include poor water quality as a result of increased nutrients and Copyright © 2020
sediments; lack of available hard bottom for corals to settle and
grow; diseases; extreme temperature changes (hot or cold); and Gulf of Mexico Fishery Management Council
frequent physical damage from storms, human activities (such as
fishing and anchoring). All Rights Reserved.
Produced with Funding and Downloadloadable version
How can you help? Support From available from
• When you dive or snorkel, don’t touch or stand on coral
reefs. Coral reefs are alive. Standing on them could break
them, stirred-up sediment can smother corals
• Don’t give corals as presents. It takes corals decades or
longer to create reef structures, so leave them on the reef. <-Scan to view
• Use appropiate sunwear, and choose sunscreens with online version

chemicals that don’t harm marine life Image Copyright: NOAA, FWC, N. Mendez-Ferrer, G.P.Schmahl, N. Hobgood
Contact: portal@gulfcouncil.org or https://portal.gulfcouncil.org