Availability of Sea Cucumber In Indian Waters And Its Importance

Dipanjan Kashyap¹, Sonmoina Bhuyan¹ and Rajita Devi²

^{1: FEES Division, Central Institute of Fisheries Education, Versova, Mumbai-400061}

^{2: College of Fisheries, AAU, Raha, Nagaon, Assam-782103}

^{Email of corresponding author: dipankashyap@gmail.com}

Introduction

Sea cucumbers are echinoderms from the class Holothuroidea (Kingdom: Animalia and Phylum: Echinodermata). They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. There are a number of holothurian species and genera, many of which are targeted for human consumption. Like all echinoderms, sea cucumbers have an endoskeleton just below the skin, calcified structures that are usually reduced to isolated microscopic ossicles (or sclerietes) joined by connective tissue. These can sometimes be enlarged to flattened plates, forming armour.

Sea cucumbers are a fascinating group of marine animals. They live chiefly among corals but are also found among rocks and in muddy and sandy flats. They are distributed from the shore to the greatest depths. Their lengths range from a few millimetres to more than 2 m and they occur in all color combinations: white, black, red, blue, green, yellow, violet etc. Some of them are really very beautiful while alive and are in great demand for aquaria. The Chinese, Japanese and Koreans consider them a delicacy. The toxins of sea cucumbers have antiviral, antitumoral, anticancerous and antifertility properties and find use in the pharmaceutical industry. At present nearly 1400 species of sea cucumbers are known from all the seas in the world. Of these only 15 species are used for processing at present.

Sea cucumbers communicate with each other by sending hormone signals through the water. Some species of coral-reef sea cucumbers within the order Aspidochirotida can defend themselves by expelling their sticky cuvierian tubules (enlargements of the respiratory tree that float freely in the coelom) to entangle potential predators. The release of these tubules can also be accompanied by the discharge of a toxic chemical known as holothurin, which has similar properties to soap. This chemical can kill any animal in the vicinity and is one more way in which these sedentary animals can defend themselves.

Some of the important sea cucumber species in Indian waters

There are nearly 200 known species in the seas around India, most of them in deep waters. About 75 species have been shown to be present in shallow waters while nearly 50 species can be collected from the intertidal region. Nearly 20 species of sea cucumber found in the Indian waters have the commercial importance. Some of the commercially important sea cucumber species are mentioned below.

1. Holothuria fuscogilva (White teatfish)

2. H. nobilis (Black teatfish)

3. H. spinifera (Brown sandfish)

4. Thelenota ananas (Prickly redfish)

5. Actinopyga miliaris (Blackfish)

6. A. mauritiana (Surf redfish)

7. A. echinites (Deep water redfish)

8. Bohadschia marmorata (Chalkyfish)

9. H. edulis (Pinkfish)

10. H. atra (Lollyfish)

11. H. scabra

12. H. impatiens

Fig 1: H. scabra Fig 2: H. fuscogilva

Fig 3: H. nobilis Fig 4: H. spinifera

Anatomy of sea cucumber

Sea cucumbers are typically 10 to 30 centimetres (3.9 to 12 in) in length, although the smallest known species is just 3 millimetres (0.12 in) long, and the largest can reach 1 metre (3.3 ft). The body ranges from almost spherical to worm-like. The anterior end of the animal containing the mouth corresponds to the oral pole of other echinoderms, while the posterior end containing the anus corresponds to the aboral pole. Thus, compared with other echinoderms, sea cucumbers can be said to be lying on their side.

Like all echinoderms, sea cucumbers possess pentaradial symmetry. Most sea cucumbers have five strip-like ambulacral areas running along the length of the body from the mouth to the anus. Sea cucumber typically possesses an internal skeleton composed of plates of calcium carbonate. In most sea cucumbers, however, these have become reduced to microscopic ossicles embedded beneath the skin. A few genera, such as Sphaerothuria, retain relatively large plates, giving them scaly armour.

Diet and digestive system

Holothuroidea are generally scavengers, feeding on debris in the benthic zone of the ocean. The diet of most cucumbers consists of plankton and decaying organic matter found in the sea. Some sea cucumbers position themselves in currents and catch food that flows by with their open tentacles. They also sift through the bottom sediments using their tentacles.

A pharynx lies behind the mouth and is surrounded by a ring of ten calcareous plates. In most sea cucumbers, this is the only substantial part of the skeleton, and it forms the point of attachment for muscles that can retract the tentacles into the body for safety as for the main muscles of the body wall. Many species possess an oesophagus and stomach, but in some the pharynx opens directly into the intestine. The intestine is typically long and coiled, and loops through the body three times before terminating in a cloacal chamber, or directly as the anus.

Reproduction and life cycle

Most sea cucumbers reproduce by releasing sperm and ova into the ocean water. Depending on conditions, one organism can produce thousands of gametes. Sea cucumbers are typically dioecious, with separate male and female individuals, but some species are protandric. The reproductive system consists of a single gonad, consisting of a cluster of tubules emptying into a single duct that opens on the upper surface of the animal, close to the tentacles.

At least 30 species, including the red-chested sea cucumber (Pseudocnella insolens) fertilize their eggs internally and then pick up the fertilized zygote with one of their feeding tentacles. The egg is then inserted into a pouch on the adult's body, where it develops and eventually hatches from the pouch as a juvenile sea cucumber. A few species are known to brood their young inside the body cavity, giving birth through a small rupture in the body wall close to the anus.

In all other species, the egg develops into a free-swimming larva, typically after around three days of development. The first stage of larval development is known as an auricularia, and is only around 1 millimetre (0.039 in) in length. This larva swims by means of a long band of cilia wrapped around its body. As the larva grows it transforms into the doliolaria, with a barrel-shaped body and three to five separate rings of cilia. The tentacles are usually the first adult features to appear, before the regular tube feet.

Holothurians as food and medicines

There are many commercially important species of sea cucumber that are harvested and dried for export for use in Chinese cuisine as Hoi sam. Some of the commonly available important food species of sea cucumber are H. scabra, H. fuscogilva, A. mauritiana, Stichius japonicas, Parastichopus californicus, T. ananas, Acaudina molpadioides etc.

Some varieties of sea cucumber (known as gamat in Malaysia or teripang in Indonesia) are said to have excellent healing properties. In foreign countries there are pharmaceutical companies being built based on gamat. But in India sea cucumber is not commercially important till today. Extracts are prepared from different parts of the sea cucumber and made into oil, cream or cosmetics. A study suggested that the sea cucumber contains all the fatty acids necessary to play a potential active role in tissue repair. Another study found that lectin from Cucumaria echinata impaired the development of the malaria parasite produced by transgenic mosquitoes.

Products made from sea cucumber

Products made from sea cucumber are sold in the markets in following forms: konowata (salted intestine), konoko (dried gonad) and dried muscle. Konowata, konoko and dried muscle of sea cucumber are considered delicacy for Japanese.

a) Konowata

The prices paid for the product are very much higher than the price for fresh sea cucumbers. In preparation of konowata, before removal of intestine, the animals are kept in clean seawater for a certain period to empty the intestine before gutting. After the intestine is removed, the contents are squeezed out by hand without breaking the canal. The intestines are washed in clean seawater and rinsed. The viscera are salted using 10—15% salt by weight of the raw viscera. One-third of the total salt are added to the product first to extract water from the body. After draining occurred, more salt is added, and mixed thoroughly for five and half hour. The mixture is put into a wood barrel and cover with a lid to allow the product fermented. Occasional stir might need during the fermenting period. The finished product is packed in bottles and distributed to retailers. The nutritive value of the product is 76.5% water, 9.3% protein, 1.3% fat, 0.5% carbohydrate and 12.4% ash. The price of konowata is paid partly on the length of the intestines. Longer intestines command higher price.

b) Konoko

This product is the most expensive product prepared from sea cucumber. It commands the price at US $200/kg. The product is not common mainly because it is difficult to procure. The product does not weigh more than 2.5% of the body weight during the spawning season. Moreover during post-spawning season the gonad is much smaller, only a small fraction of a percent of body weight.

Removal of gonad as well as intestine from sea cucumber does not to kill animals. Small incision on body wall is enough to remove the gonad and intestine. The cut made on the body wall will heal in 5—7 days. The intestine will regenerate, and the same quality or even more can be obtained in the following year.

c) Dried muscles

This product is made from the longitudinal muscles of sea cucumber. It is tender and taste like high quality clam meats. Beside Japanese and Chinese, the product is also palatable to American and European. It is a high potential product for those markets. The removal of the long, thin longitudinal muscles is facilitated by placed the sea cucumber in pure, clean seawater to contract or shortening the muscles. The muscle are preserved in brine, and sold in market in canned products.

d) Beche-de-mer

This product used in gourmet soups or other delicacy Chinese dishes. It is the most common product made from sea cucumber. Price paid for the beche-de-mer varies greatly depending on the species of sea cucumber used and the care given during processing. The best species are large and the body walls are thick. Factors that may influence the quality of the product during processing are:

1. The sea cucumber takes a long time to die and the body disintegrates before death. It should be killed instantly by immersion in boiling seawater to preserve its wholesomeness.

2. Scum from fine mud and debris on its body wall have to be removed without loosing the nutritive matter of the body wall. Partial decomposition or softening of the outer wall facilitates removal of scum.

On completion of processing, the product is graded on the basis of length, appearance, odor and weight per kg. Packing materials are copra sacks, jute-hessian sacks and plastic bags. To avoid the re-drying, the vacuum pack may be a necessity. The good quality of product should have uniform, non-distorted shapes. It should be hard and dry, moisture content allow up to 20—30 per cent. The product should have a pleasing odor and be free of dirt.

Scope of sea cucumber farming in India

Studies conducted in India showed that the sea cucumber juveniles and young adults of Holothuria scabra grow relatively fast in prawn farms by making use of the feed waste. The growth of the sea cucumber juveniles is three times faster when they are grown in the prawn farm without affecting the normal prawn farming activities. If juvenile H. scabra are produced in good numbers it is advisable to release them directly into the farm at the rate of 30000 juveniles/hectare. The growth rate is expected to be better when freely grown in the prawn farm rather than in a confined space like a concrete ring. The juveniles are expected to reach harvestable weight at the end of one year.

Conclusion

Sea cucumber farming is now becoming popular in most of the south-east Asian countries. But except the wild catch, it is not commercially cultured in the water bodies of India. Proper planning and initiative is utmost necessity in this direction to enhance the production of sea cucumber throughout the country. Moreover good policy and subsidy schemes are also important to attract the farmers. So Government should take the initiative to enhance its farming in the country.

References

• Asha, P.S. & Rodrigo, J.X. 2001. Spawning and larval rearing of the sea cucumber, Holothuria (Theelothuria) spinifera Theel at Tuticorin. Marine Fisheries Information Service, Technical & Extension Service,169:11-13.

• Asha, P.S. & Muthiah, P. 2002. Spawning and larval rearing of the sea cucumber Holothuria (Theelothuria) spinifera Theel. Beche-de-mer Information Bulletin, 16:11-15.

• Battaglene, S.C. 1999. Culture of tropical sea cucumbers for stock restoration and enhancement. Naga 22(4):4—11.

• Chen, C.P. and C.S. Chian. 1990. Larval development of the sea cucumber, Actinopyga echinites (Echinodermata. Holothuroidea). Bull. Inst. Zool. Acad. Sci. 29:127—133.

• James, D.B., M.E. Rajapandian, B.K. Basker and C.P. Gopinathan. 1988. Successful induced spawning and rearing of the holothurian Holothuria (Metriatyla) scabra Jaeger at Tuticorin. Mar. Fish. Infor. Ser., T & E. Ser., 87:30—33.

• James, D.B. 1993a. Sea cucumber culture. In: Sea Weed, Sea Urchin and Sea Cucumber. Handbook on Aquafarming. p.33-47. The Marine Products Export Development Authority, Cochin.

• James, D.B. & Badrudeen, M. 1995. Deep water Red Fish - a new resource for the Indian Beche-de-mer industry. Marine Fisheries Information Service, Technical & Extension Service, 137:6-8.

• James, D.B. 1997. Sea cucumber hatchery and culture prospects. National Aquaculture Week. p.1-6. Organised by Aquaculture Foundation of India, Madras.

• James, D.B. and M. Badrudeen. 1997. Observations on the landings of the sea cucumber Holothuria spinifera at Rameswarm by Chanku madi. Mar. Fish. Infor. Ser., T & E. Ser., 149:6—8.

• Ramofafia, C., M. Gervis and J.D. Bell. 1995. Spawning and early larval rearing of Holothuria atra. SPC Beche-de-mer Information Bulletin 7:2—6.