• Corals are marine invertebrates in the class Anthozoa of phylum Cnidaria.
• Phylum containing over 10,000 species of animals found exclusively in
aquatic (freshwater and marine) environments: they are
predominantly marine species.
• From taxonomic point of view members of the Phylum Cnidaria are regarded
as first metazoan animal.
• Hyman (1940) presented the classification of Coelenterata.
• Recently the name Cnidaria in place of Coelenterata is used because
Ctenophora has been separated from it and given the status of a Phylum.
• A group of diploblastic animals with radial
symmetry, without organ system and anus and
having single tubular gastrovascular cavity and with
tentacles and nematocysts is recognized as
General Characters of Cnidaria
1. Cnidarians are multicellular animals and first
metazoan with tissue grade of construction.
2. Most of the Cnidarians are marine, though some
are fresh water forms.
3. Body radially symmetrically
4. A single coelenteron or gastrovascular cavity is
present which opens through mouth, anus is
5. Small and narrow tentacles surround the mouth in
circlet. Tentacles are used to procure food and for
6. Body is covered by epidermis, gastrovascular
cavity is lined by endodermis and in between the
two there is a layer of non cellular matrix known
7. Body diploblastic and so coelom is present.
8. No Circulatory system, use cellular diffusion and
9. Nervous Nerve net (ring around the bell of medusa)
10.Endocrine have hormones, secreted by nervous system.
11.The colonies show polymorphism with polyp and
medusa as basic Zooids. Polyp represent asexual form
and medusa represents sexual zooid.
12.A special type stinging cells known as nematocysts are
present. These cells help in defenses and food capture.
13.Ciliated planula larva is found.
14.In the life cycle alternation of generation and
metagenesis are found.
The developmental stages of scyphozoan jellyfish's life cycle: 1–3 Larva searches for site 4–8 Polyp
grows 9–11 Polyp strobilates 12–14 Medusa grows
Classification of Phylum Cnidaria
The basis of classification is the adult forms whether polyp or medusa.
Phylum Cnidaria has been classified into four Classes-
Class I: Hydrozoa (a diverse group that includes all the freshwater
cnidarians as well as many marine forms, and has both sessile
members, such as Hydra, and colonial swimmers, such as
the Portuguese Man o' War)
Class II: Scyphozoa (jellyfish), swimming
Class III: Anthozoa (sea anemones, corals, sea pens)
Class iv: Cubozoa (box jellies)
Class I- Hydrozoa
• Fresh water members of this class live singly, but
the marine forms live singly or form polymorphic
• Though only polyp or medusa is found but
sometimes both polyp or medusa may be found
in the same animal.
• Gastrovascular cavity is directly connected with
• Alternation of generation is found in the life
• Ciliated planula larva is found.
• No stomodeum, velum present in medusa.
• Radial canals in medusa are not branched.
• Gametes develop from ectoderm.
Class II- Scyphozoa
• Larger medusa, free swimming, all are
marine.(referred to as the true jellyfish)
• Polyp absent or reduced.
• Gastrovascular cavity branched.
• Well developed nematocyst very active.
• Gastric tentacles and gametes developed from
• Mesoglea thick, fibrous and contains
• Sense organs as tentaculocyst.
• Many tentacles hang from the velum.
Class - Anthozoa
• Largest class of cnidarians, containing over 6,000 species.
• Mouth surrounded by tentacles with nematocysts.
• Partioned gastro vascular cavity.
• Secretes substance around outside of body to support
and protect soft body tissues.
• Reproduces sexually by producing a free-swimming larva
(planula) or asexually by budding or fission.
• Cylindrical, with radial symmetry.
• No alternation of generation - polyps only
• Anthozoans include sea anemones, a variety of corals, sea fans, and sea pens.
Subclass - Octocorallia (Alcyonaria)
• It comprising around 3,000 species of water-based organisms formed of
colonial polyps with 8-fold symmetry.
• Colony may be simple or plant like.
• These organisms have an internal skeleton secreted by mesoglea.
• Tentacles and mesenteries 8 or in multiples of 8.
• As with all Cnidarians these organisms have a complex life cycle including a
motile phase when they are considered plankton and later characteristic
• It includes the blue coral, soft corals, sea pens, and gorgonians (sea fans and
sea whips) within three orders: Alcyonacea, Helioporacea, and Pennatulacea .
Order: Alcyonacea (soft corals & gorgonians)
Soft corals contain minute, spiny skeletal elements called sclerites, useful in species
Sclerites give these corals some degree of support and give their flesh a spiky, grainy
texture that deters predators.
Unlike stony corals, most soft corals thrive in nutrient-rich waters with less intense light.
Almost all utilize symbiotic photosynthesizing zooxanthella as a major energy source.
However, most will readily eat any free floating food, such as zooplankton, out of the
Many soft corals are easily collected in the wild for the reef aquarium hobby. Soft corals
grow quickly in captivity and are easily divided into new individuals, and so those grown
via aquaculture are often hardier and less expensive than imported corals from the wild.
Yellow Leather Coral
• The Yellow Leather Coral Sarcophyton elegans is a favorite coral from
the Sarcophyton genus. The majority of the Sarcophyton sp. have a
thick smooth, single stalk with a flared, smooth mushroom-shaped
top that can be folded or funnel-shaped. The S. elegans however has
less of a stalk, and grows closer to the rock work.
• "top" is called a capitulum, and within that area are found autozooid
polyps for feeding and siphonozooid polyps for water movement. The
polyps can retract all the way, giving it a smooth look at times.
Yellow Toadstool Leather Coral
• The Yellow Toadstool Leather Coral or Gold-Crowned Leather
Coral Sarcophyton tenuispiculatum is popular leather coral favorite in
the Sarcophyton genus. The Sarcophyton sp. have a thick smooth,
single stalk with a flared, smooth mushroom-shaped top that can be
folded or funnel-shaped.
• Depending on the species, younger colonies are mushroom-shaped
and mature colonies are more lobed and folded like a toadstool.
Some keep the toadstool look their entire life. The flesh is firm and
soft, yet can be easily torn. The "top" is called a capitulum and within
that area are found autozooid polyps for feeding and siphonozooid
polyps for water movement.
Cabbage Leather Coral
• One of the best known octocorals is the Cabbage Leather
Coral Lobophytum crassum. They are a soft coral that have a thick
and heavy "skin" with lobed projections, and form a low encrusting
colony. They resemble a cabbage in that their curved, cupped shape
looks like a large ruffled leaf. Some other descriptive common
names include Rabbit Ear Leather Coral, Flower Coral, and Lobed
• The Cabbage Leather Coral is a hardy, adaptable coral. They come
from a wide variety of environments at depths of 20 to 60 (6 to 18
m). They are found near the shore on shallow waters reef flats,
where they are most prolific, as well as turbid lagoons attached to
rubble. Some are exposed to low tide as well.
The Lobophytum species are some of the first soft corals to enter
the aquarium trade because they travel well.
• The polyps of the Cabbage Leather Coral are on the outside edge
of the "leaves". They look more like tufts instead of the fully
developed polyps seen on other corals. When feeding the polyps are
out, and as nutrients are captured, the polyps retract. The flesh feels
grainy, and can be brittle, so handle with care.
• The Lemnalia genus can be hard to differentiate from the others in
the Nephtheidae family, but like all families, there is always the
thin kid. In general, the Tree Coral Lemnalia sp. has a thinner stalk
than others in their family, and that stalk has no polyps. Also on its
thin branches and branchlets, the polyps are more or less
scattered, as opposed to the dense populations of the other
• Lemnalia corals are branching and are usually found in areas of
moderate to strong water movement.
• Their colors are usually cream to brown, white, or pinkish brown
with the polyps being very close in color, though maybe a little
darker than the main body.
• Some common names they are known for are Tree Coral,
Cauliflower Coral, Branch Coral, Lemnalia Coral, Lemnalia Tree
Coral, Broccoli Coral, and Kenya Tree Coral.
• Of the soft coral genera belonging to the Nephtheidae family, the
Tree Coral is not as hardy as members of the Capnella genus, like
the durable Kenya Tree Coral Capnella sp.. Yet they are also not as
hard to care for as the needy members of
the Dendronephthya genus, which contain the colorful Carnation
Corals Dendronephthya sp.
Order Helioporacea (blue corals)
• It forms massive lobed crystalline calcareous skeletons in colonial corals.
These corals first appeared in the Cretaceous period.
• The blue coral (Heliopora coerulea), the only species in the
family Helioporidae, is most common in shallow water of the tropical Pacific
and Indo-Pacific reefs.
• It has no spicules, and is the only octocoral known to produce a massive
skeleton formed of fibro crystalline aragonite fused into lamellae.
• They form large colonies that can exceed a meter in diameter. They are
composed of vertical branches.
• The entire skeleton, however, has an unusual blue color and therefore the species is
commonly exploited for decorative uses.
• The blue color of the skeleton is caused by iron salts. Blue coral can be used in tropical
aquaria, and the crystalline calcareous fibres in the skeletons can be used for jewelry.
• Cilia (tiny hair like projections) on six septa draw water into the cavity. Cilia on the
other two septa expel water.
Family: Helioporidae (1 genus, 1 species)
• Heliopora coerulea
Family: Lithotelestidae (1 genus, 4 species)
• Genus Epiphaxum
• Hexacorallia comprising approximately 4,300 species of aquatic organisms
formed of polyps, generally with 6-fold symmetry.
• It includes all of the stony corals, most of which are colonial and reef-forming,
as well as all sea anemones, tube anemones, and zoanthids.
• These organisms are formed of individual soft polyps which in some species
live in colonies and can secrete a calcite skeleton.
• As with all Cnidarians, these organisms have a complex life cycle including a
motile planktonic phase and a later characteristic sessile phase.
• Hexacorallia also include the significant extinct orders of the rugose
corals and tabulate corals. Haeckel, 1866 (6 orders)
order Corallimorpharia (Mushroom corals)
• Corallimorphidae (2 genera, 22 species)
• genus Corallimorphus -- 6 species, Corallimorphus antarcticus
• genus Corynactis -- 16 species, Corynactis australis
• Discosomatidae (4 genera, 20 species)
• genus Amplexidiscus -- 1 species
• genus Discosoma -- 11 species
• genus Metarhodactis -- 1 species
• genus Platyzoanthus -- 1 species
• genus Rhodactis -- 6 species
• genus Ricordea -- 2 species, Ricordea florida.
• genus Nectactis -- 1 species, Nectactis singularis.
• genus Sideractis -- 1 species, Sideractis glacialis.
• The Rugosa, also called the Tetracoralla, are an extinct order
of coral that were abundant in Middle Ordovician to Late Permian seas.
• Solitary rugosans (e.g., Caninia, Lophophyllidium,Neozaphrentis, Streptelasma) are often referred to
as horn corals because of a unique horn-shaped chamber with a wrinkled, or rugose, wall.
• Some species of rugose corals could form large colonies (e.g.Lithostrotion)
• Rugose corals have a skeleton made of calcite that is often fossilized. Rugose corals were
invariably benthic, living on the sea floor or in a reef-framework.
• Some symbiotic rugose corals were endobionts of Stromatoporoidea, especially in the Silurian.
• Although there is no direct proof, it is inferred that these Palaeozoic corals possessed stinging cells
to capture prey.
• They also had tentacles to help them catch prey. Technically they were carnivores, but prey-size was
so small they are often referred to as microcarnivores.
Order Scleractinia (stony corals)
• There are two main ecological groups. Hermatypic corals are
mostly colonial corals which tend to live in clear, oligotrophic,
shallow tropical waters; they are the world's primary reef-builders.
• Ahermatypic corals are either colonial or solitary and are found in all regions of
the ocean and do not build reefs. Some live in tropical waters but some
inhabit temperate seas, polar waters, or live at great depths, from the photic
zone down to about 6,000 m (20,000 ft).
• The order Scleractinia includes all post-Paleozoic fossil and recent corals.
• The Scleractinia are distinguished by a calcareous external skeleton.
• Veron (2000) reported 18 families, 111 genera and 793
species of Scleractinia from the world.
• Wallace (1999) reported 114 species of the genus Acropora
in her book on ‘Staghorn corals of the world.
Orange Sun Coral
• The Orange Sun Coral Tubastraea faulkneri is so gorgeous, it often is found on the covers of
coffee table books and books that specialize in corals.
• The corallites of the Orange Sun Coral, the hard round, tubular structures that the polyps live
• The corallites are covered with a tissue, called the coenosteum.
• The fleshy tentacles of its polyps are bright yellow with the coenosteum having a bright orange
color, and the very center of the polyps are also bright orange.
• They extend their polyps mostly during the evening hours, though they can be coaxed out
during the day if food is present.
• During the day the coral is completely withdrawn and only the bright orange coenosteum is
visible, making it look like a ball with raised round flat nubs.
• The Orange Sun Coral can form colonies around 6" (15 cm) in diameter. They are slow growers,
only adding about 1.6" of growth per year. The T. faulkneri are also ahermatypic, which means
they don't contribute to reef building.
• The Scrolling Tubinaria Coral Turbinaria reniformis is one of the most recognized of
the Turbinaria genus. In mature specimens, their scroll-like or whorled shape can be either vertical
or more horizontal, depending on the depth in which they are found.
• Specimens found at deeper levels have a plate like or flatter, horizontal appearance.
• That can change to a scroll like, upright shape in shallower water with brighter lighting.
• Their shapes include vase, plate, and columnar, yet they are quite adaptable. They will robustly
change shape with a change in environment. If one were to transplant a shallow dwelling species to
deeper levels, or visa versa, they will actually change shape to make the most out of the lighting in
• Besides having various shapes, Turbinaria corals also have variations in their polyps. One side of any
plate or column generally has polyps or at least tissue coverage. The color of the Scrolling Coral T.
reniformis is usually a yellowish or greenish brown, usually with yellow polyps and a yellow edge.
• Turban Coral
• The handsome Turban Coral Turbinaria peltata is a definite favorite from the Turbinaria genus.
The corallites of its skeletal structure are knobby as opposed to an 'ant hill' tubular type, and
they are close together. I
• ts polyps are big and frilly, covering the underlying skeleton so well that the coral almost looks
• Turban Corals T. peltata are typically sold in the "cup" form, yet again depending on the depth
that they are captured, they can become columnar in shape.
• The characteristic Turbinaria shapes are reflected in the Turban Coral's other common names
including Cup Coral, Pagoda Cup Coral, Green Cup Coral, Chalice Coral, Column Coral, Bowl
Coral, Octopus Coral, Plate Coral, Vase Coral, Disk Coral, Platter Coral, and Saucer Coral.
• One side of any plate or column generally has polyps or at least tissue coverage. The Turban
Coral has large fleshy polyps with calices (opening of the corallite) that are 3 to 5 mm in
• The color of the T. peltata can be brown, yellow, gray, and greenish gray blue with some cream
Hedgehog Coral (Echinopora Sp.)
• The Echinopora genus is often found with Clown Goby species from the genus Gobiodon bopping
around its surface.
• These energetic little coral gobies hardly reaching 2 1/2 inches, and they have a toxic body slime so
other fish don't bother with them.
• They are quite content living among Hedgehog Corals as well as Acroporas, much like a clownfish
and an anemone.
• The Hedgehog Coral species most commonly seen in the aquarium trade are the Leafy Hedgehog
Coral E. lamellosa and Hedgehog Coral E. mammiformis. Also E. horrida is seen from time to
time. E. lamellosa colonies form whorls and tiers, with a rare tubular shape here and there. E.
mammiformis colonies have flat plates as bases and form bent branches. E. horrida colonies are
unique in that they have branches, shooting out of a plate-like base, that twist and bend.
• Echinopora colors include amber, tan to dark brown, cream, green, mustard yellow, pink, and
purple; with the center of the corallite having contrasting colors.
Maze Brain Coral
• The Maze Brain Coral Platygyra sp. has beautifully contrasting walls and valleys. In
the wild they form massive colonies that can be either flat or dome shaped.
• The Platygyra genus are commonly meandroid, meaning they develop valleys. On
occasion they may also have cerioid, meaning shared walls, mixed in.
• The Brain Maze Coral or Maze Coral P. lamellina is the most common species in the
trade, which could be due to its abundance in the shallower waters. P. daedalea is
another commonly available species. Others include P. sinensis and P. pini.
• This genus is moderate to care for. They are not as hardy as other members of the
Flaviidae family, and are more likely to bleach and have tissue loss from stress.
However once acclimated, if you provide these corals with regular feedings, they
will grow quickly. The Platygyra genus has been propagated in captivity on local
• The Disk Corals from the Fungia genus are quite hardy creatures that easily move about on the substrate.
• They can actually move up to 12" per day (30 cm). They have also been known to climb slight slopes up to a 30
degree angle, and to right themselves if they get flipped over.
• The Disk Coral Fungia sp. is a free-living creature that is quite mobile. They will travel by inflating their tissue
and using current to move.
• They have saucer to dome shapes that can be dented or elongated.
• All species of Fungia have wide slit-like mouths, often housing various parasites.
• They can have one mouth or more mouths with long septa that radiate from the center all the way to the end.
Some septa start further back and are smaller than the main ones
• Fungia spp. have short tapering tentacles, which in the wild retract during the day, coming out only at night.
• Tentacles are nestled between the blade-like septal teeth that radiate out from the center. When young
the Fungia spp. are connected with a stalk to rock work. Over time as the coral develops, the stalk gradually
weakens and breaks, leaving a central scar. The scar is then gradually overgrown.
• The Disk Coral comes in a wide array of colors that make them an attractive addition to your display. They are
most commonly green or purple, but just name the color and the Fungia genus comes in it. Some of the more
common Fungia spp. are described here:
• The Plate Coral H. actiniformis is a free-living polyp whose tentacles are so long
they hide their skeletal structure. They can be mistaken as an anemone at first
glance. Their shape can be oval or round, and with or without an arch in the
middle. They can get up to 8" (20 cm) across, and the mouth can be 1" (3 cm)
wide. Lifespan is unknown.
• The Long Tentacle Plate Coral is not quite as colorful as the Fungia genus. They
all have striped oral discs or mouths. Their base color can be olive, brown, dark
purple, yellow, or green with tentacles that have contrasting tips that are white,
pink, yellow, grayish violet, green or white.
Open Brain Coral
• Open Brain Coral Trachyphyllia geoffroyi - was described by Audouin in 1826.
• The Open Brain Coral T. geoffroyi forms free-living polyps that have valleys with
their own corallite walls.
• They can have up to 3 separate mouths, reaching up to just over 3" (8 cm)
across, but the width of their valleys is just under 1/2" (10 mm) across.
• Their septa, or the "teeth" on the inside of the corallite wall, are large and form
a ridging look under the flesh.
• The base of the coral is cone shaped, giving away its naturally soft substrate
habitat. Their polyps are large fleshy mantles, and they come in a variety of
bright colors including yellow, red, pink, brown, blue or green.
Pacific Rose Coral
• Pacific Rose Coral Trachyphyllia radiata - has been bounced around a bit. It had previously
been classified in its own genus as Wellsophyllia radiata, then reclassified to
the Trachyphyllia genus. There is still ongoing discussion on where it should be classified. It can
be found referred to as one or the other, but generally as Trachyphyllia radiata.
• The Pacific Rose Coral T. radiata is very much like the Open Brain Coral T. geoffroyi, but it is
always distinctly round rather than flat, and usually more folded in form.
• They grow in colonies once mature.
• The T. geoffroyi forms free-living polyps that have valleys with their own corallite walls, while
the walls on the T. radiata are fused.
• The Pacific Rose coral also has a flattened bottom is attached to hard substrate, rather than the
cone-shaped bottom found on the T. geoffroyi used to anchor itself into soft substrates.
• Their polyps are large fleshy mantles, and they come in varying shades of brilliant metallic
greens, reds, and pinks. Trachyphyllia corals can have up to 3 separate mouths, reaching up to
just over 3" (8 cm) across, but the width of the valleys are just under 1/2" (10 mm) across. The
septa, or the "teeth" on the inside of the corallite wall, are large and form a ridging look under
the flesh. The Trachyphyllia corals feed at night, extending polyp tentacles. They can be long-
lived in captivity, but their actual life span is unknown.
Importance of corals
• Help in conserving aquatic biodiversity.
• Having symbiotic relationship with so many fishes, algae and crustaceans.
• Coral reefs provide medical benefits for humans.
• Coral skeletons are also commonly used for bone grafting in humans.
• The global trade of marine ornamentals has been a rapidly expanding industry involving numerous
• Provide aesthetic benefit to humans in terms of their beauty of colour and form.
• In climate research - The annual growth bands in bamboo corals allow geologists to construct year-
• Deep sea bamboo coral - may be among the first organisms to display the effects of ocean
acidification. They produce growth rings similar to those of tree, and can provide a view of changes
in the condition in the deep sea over time.
• Coral reefs are dying around the world due to global warming, pollution, Sedimentation,
Dredging, ocean acidification, Coral diseases, starfish infestation, blast fishing & Tourism
• In El Nino-year 2010, reports show global coral bleaching reached its worst level since
another El Nino year, 1998, when 16 percent of the world's reefs died as a result of
increased water temperature.
• In Indonesia's Aceh province, surveys showed some 80 percent of bleached corals died.
• General estimates show approximately 10% of the world's coral reefs are dead.
• About 60% of the world's reefs are at risk due to destructive, human-related activities.
• The threat to the health of reefs is particularly strong in Southeast Asia, where 80% of
reefs are endangered.
• Identification of marine protected areas and their demarcation and protection.
• Coral Reef Monitoring Action Plans prepared and launched.
• Other significant international activities such as the Coral Reef Degradation in the Indian
Ocean (CORDIP), India–Australia Training and capacity building programme (IATCB),
• National wide mapping of coastal areas by remote sensing techniques combined with land
surveys to assess the rate of degradation initiated.
• Workshops, symposia, seminars and national conferences have discussed the problems
of coral reefs and have made several recommendations for their conservation and
• In addition several national and state level committees with a view to protecting our reefs have been
• Coral aquaculture, also known as coral farming or coral gardening, is
showing promise as a potentially effective tool for restoring coral reefs.
• Efforts to expand the size and number of coral reefs generally involve
supplying substrate to allow more corals to find a home.
• Substrate materials include discarded vehicle tires, scuttled ships, subway
cars, and formed concrete, such as reef balls.
• Bayer, F. M. 1956. Octocorallia. Pp. F166-F230 in: R. C. Moore (ed.), Treatise on Invertebrate
Paleontology Part F: Coelenterata. Geological Society of America and University of Kansas Press,
• Bayer, F. M., M. Grasshoff, and J. Verseveldt. 1983. Illustrated trilingual glossary of morphological
and anatomical terms applied to Octocorallia. E. J. Brill / Dr. W.Backhuys, Leiden. 75 pp.
• Berntson, E. A., S. C. France, and L. S. Mullineaux. 1999. Phylogenetic relationships within the Class
Anthozoa (Phylum Cnidaria) based on nuclear 18S rDNA sequences. Molecular Phylogenetics and
Evolution 13: 417-433.
• Kenji Konishi, "Alcyonarian spiculite: the limestone of soft corals", 1981; M.-S. Jeng, H.-D. Huang, C.-
F. Dai, Y.-C. Hsiao and Y. Benayahu. (15 May 2011), "Sclerite calcification and reef-building in the
fleshy octocoral genus Sinularia (Octocorallia: Alcyonacea)", Earth and Environmental Science, Coral