INTRODUCTION Gorgonians are marine coelenterates (referring to the hollow body cavity) of the class Anthozoa, which include sea fans, sea whips, corals, sea anemones, and other related species. Gorgonids are soft corals commonly known as sea fans or sea whips, coming under the subclass Octocorallia and have eightfold radial symmetry. It composed of numerous polyps—cylindrical sessile (attached) forms—that grow together in a flat fanlike pattern. They are colonial animals that have a beautiful, branching structure that is covered by soft tissue and are generally found in warm waters and around reefs. ​

1. BIOLOGY OF GORGONIDS
(SEAFANS)
Vinod Kumar
FRM

2. INTRODUCTION
• Gorgonians are marine coelenterates (referring to the hollow
body cavity) of the class Anthozoa, which include sea fans, sea
whips, corals, sea anemones, and other related species.
• Gorgonids are soft corals commonly known as sea fans or sea
whips, coming under the subclass Octocorallia and have
eightfold radial symmetry.
• It composed of numerous polyps—cylindrical sessile
(attached) forms—that grow together in a flat fanlike pattern.
• They are colonial animals that have a beautiful, branching
structure that is covered by soft tissue and are generally found
in warm waters and around reefs.

3. CLASSIFICATION
• Kingdom - Animalia
• Phylum - Cnidaria
• Class – Anthozoa
• Subclass - Octocorallia
• Order – Alcyonacea (soft corals)
Gorgonacea (seafans, sea whips etc.)

4. DISTRIBUTION
• There are about 500 species of Gorgonia, and they differ
markedly in their branching patterns.
• Sea fans are found in the shallow waters of all oceans, but they
are especially abundant along the South Atlantic coasts of
Florida, Bermuda, West Indies, Indo-Pacific, and also in
Malay Archipelago and Bahamas.

5. HABITAT
• It exists in colonial form in all seas from tide mark to over 4000 m.
• They can be found in many different ocean habitats, but are most
common in the tropics.
• Some prefer to grow in warmer seas. Majority of them are littoral.
• They form branches in all direction in deep sea & fan-like structure
in shallow water.
• It forms attractive features of coral reefs & submarine gardens.

6. CHARACTERISTICS AND
MORPHOLOGICAL FEATURES
• Gorgonians can get pretty large, up to 3 feet tall
by 3 feet wide.
• Body looks like fan-shaped.
• Colonies are erect, branching and tree-like.
• They are sessile or immobile; colonies grow
attached to a hard surface.
• Body consists of pedal disk, arborescent branches, stalk and polyps.
• Branches are in one plane and are connected by many cross-
branches forming a mesh or network.
• Pedal disk act as a hold fast organ where the base of the colony is
expanded.
• Many small and retractile polyps are present in rows on both sides
of the stem and branches.

8. CONTD.
• Each polyp in the colony has eight tentacles.
• A central internal skeleton, composed of a flexible, horny
scleroprotein called gorgonin, supports all branches of the colony,
and the living tissues form a layer over its entire surface.
• The tissues are often coloured in hues of red, yellow, or orange.
• Shallow layer of coenenchyme covers the central axial rod which
contains polyps with gastrovascular cavities and variously shaped
loose calcareous spicules.
• These exhibit high power of regeneration.
• Sexes are separate.
• Although the sea fans have branches, most of these organisms are
flat, rather than bushy.

9. FOOD AND FEEDING
• Sea fans use their polyps to trap small food particles, such as
phytoplankton and bacteria as polyps spread out their
tentacles to form a plankton-catching net.
• In most cases the fan-shaped colonies grow across the
current, which increases their ability to ensnare prey.
• The fan’s wide, branched shape is perfect for filtering as
much water as possible as it passes by.
• Gorgonians, like other filter feeders, therefore are important
for helping keep the ocean’s water clean.

10. • Some gorgonians are inhabited by zooxanthellae,
dinoflagellates that conduct photosynthesis. The gorgonian
benefits symbiotically from the nutrients produced during
that process.
• Other species, especially those that live in deep waters where
sunlight doesn’t reach, survive without them, just getting food
by filter feeding.

11. REPRODUCTION
• Some gorgonians reproduce sexually. Male and female
colonies of sea fans broadcast sperm and eggs into the water
column.
• The fertilized egg turns into a planula larva. This larva swims
at first and then metamorphoses and settles to the bottom and
becomes a polyp.
• From the first polyp, additional polyps bud to form a colony.

12. • These corals may also reproduce asexually, such as when they
bud from one polyp, or produce a new colony from a fragment
of coral. ie, Each newly metamorphosed polyp eventually
gives rise to an entire sea fan colony through asexual budding.

13. GORGONIDS IN INDIA
• In India, they are associated with other species of hard reef
corals along the Gulf of Mannar, Tuticorin, Kilakarai,
Rameswaram, Nagapatnam, Cuddalore and Chennai on the
east coast.
• Though gorgonids are distributed all along the coasts of India,
their presence in fishable magnitude is noted only in the Gulf
of Mannar.
• Although the diversity of gorgonid species in Indian waters is
high, taxonomic and ecological studies to date are inadequate
for reliable identification of most species, preventing rational
and sustainable use of this marine resource.

14. • 22 species of gorgonids are being exploited from the Indian
Seas at present and these are referable to 7 families and 15
genera.
• The important families being Paramuriceidae and Ellisellidae
with nine and seven species respectively.
• Species such as Echinomuricea indica, Heterogorgia
flabellum, Gorgonella umbraculum , Leptogorgia
australiensis and Junceella juncea, form the mainstay of the
export in the order of abundance.

15. COMMERCIAL CLASSIFICATION
OF INDIAN GORGONIDS
• Gorgonids exported from India are commercially classified
under four heads or types:
Black
Red
Flower and
Monkey tail.

16. 1.Black type: Specimens are black or dark brown in colour and
the body pattern may be mostly reticulated. Branches divide
in one plane and give rise to an ovate colony form; stalk may
be short and stout.
• Eg; Echinomuricea indica, Heterogorgia flabellum,
Echinogorgia complexa etc.

17. 2.Red type: Specimens may be pink or brick red in living
condition. Body pattern resembles very much that of the
above type.
• Eg; Gorgonella umbraculum, Subergorgia
reticulata,Subergorgia suberosa etc.

18. 3.Flower type: Specimens may be yellow/, red, orange, white
or cream in colour. Body pattern may be lamellar or bushy
with free branches. Young specimens of Red type may often
be sorted out under this category.
• Eg; Leptogorgia australiensis

19. 4.Monkey tail type: Colony long and whip-like; seldom
branching, if dividing, often dichotomously.
• Eg; Junceella juncea

20. TYPE WISE CONTRIBUTION TO
FISHERY
• Average contribution to the fishery by,
Black type- 38.3%
Red type- 25.7 %
Monkey tail type- 20.3 %
Flower type-15.7%.

21. IMPORTANCE AND USES OF
GORGONIDS
• Host for other marine animals
• Biochemical and pharmaceutical value
• Ornamental value
• Aesthetic value
• Export value

22. 1.SEA FANS- HOST FOR OTHER
MARINE ANIMALS
• Sea fans also act as important habitats for other critters.
• Tiny pygmy seahorses perch on their branches, using their
long, prehensile tails to hold on. The seahorses have knobby
bodies that blend in perfectly with their coral home.
Eg; common pygmy or Bargibant's seahorse.
• Bivalves, sponges, algae, brittle stars, and basket stars and
fishes also live on sea fans.
• These animals are often perfectly adapted for living upon a
specific sea fan and they can sometimes be nearly invisible on
their resident sea fan because they are so perfectly
camouflaged.

24. 2.BIOMEDICAL AND
PHARMACEUTICAL USES
• They have become an important study object in marine
biotechnology due to the presence several chemical
compounds with potent anti-microbial, anti-cancer and anti-
inflammatory activities.
• Most important one is prostaglandins, medically useful for
birth control, prevention of peptic ulcers, treatment of
asthma, regulation of blood pressure etc.
• The discovery of prostaglandins in gorgonids and their
clinical possibilities initiated a general interest in this group
as an easily available source of several 'wonder drugs'.

25. CONTD.
• The exploitation of gorgonids on a commercial basis from the
Indian Seas since 1975 may be said to be a part of this world-wide
'hunt' for raw materials.
• Gorgonids are also known to be a rich source of terpenoids. So far
about 74 such compounds have been isolated from different species
and these may be classified under diterpene, sesquiterpene and
artifact.
• They have large medicinal value like anti-inflammatory,wound
healing properties etc.
• Many of the species known from Indian waters are rich in Asperdiol,
Crassin acetate, Cadinene, Corgonene etc.
• Some of these chemicals exhibit antineoplastic properties.

26. 3.ORNAMENTAL AND
AESTHETIC VALUE
• Because of their beauty, gorgonians are also been exploited
for decorative and ornamental purposes in the aquarium
trade.
• Sea fans may be collected and dried and sold as souvenirs.
• One of the best ways to enjoy sea fans is in the wild. Sea fans
create a colorful, calming presence while you're scuba diving
or snorkeling near a coral reef.

27. 4.EXPORT VALUE
• These organisms are now being exported to several countries
at an average rate of 3.6 tonnes per year under rough
commercial grouping of black, red, monkey tail and flower
types.
• Black and Red types have heavy demand in the foreign
market.
• The increasing demand for gorgonids from India by foreign
agencies resulted in indiscriminate fishing of this commodity
along our coasts and this culminated in the depletion of many
of our rich gorgonid beds.

28. CONSERVATION STATUS
• Eunicella verrucosa - pink sea fan-
vulnerable(VU)

29. THREATS
• Global climate changes
• Thermal stress
• Ocean acidification
• Unsustainable fishing activities
• Land based pollution
• Overexploitation
• Recreational misuse
• Dredging, quarrying etc.
• Unscientific developments
• Tourism activities.

30. CONSERVATION MEASURES
• Prevent the illegal trade.
• Exploitation should be optimized - implement quota system
for each species.
• Sustainable harvesting- conservative pruning
• Fix a minimum size for each species at which their
exploitation could be commenced.
• Reduce destructive fishing gears and practices.
• Reduce the pollution load.

31. REFERENCES
• P. Thomas, R. George (1986). Asystematic appraisal of the
commercially important gorgonids of the indian seas. Journal
of the marine biological association of India.
• https://www.britannica.com/animal/coral
• https://www.vedantu.com/animal/sea-fan