Biology Of Gorgonids.pptx

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.

7. 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.

8. 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.

9. 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.

10. 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.

11. 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.

12. 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.

13. 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.

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

15. 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.

16. 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.

17. 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

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

19. 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%.

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

21. 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.

22. 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'.

23. 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.

24. 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.

25. 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.

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

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

28. 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.

29. 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