Marine Ornamental Molluscs

MARINE ORNAMENTAL MOLLUSCS

V. Venkatesan Mandapam Regional Centre of Central Marine Fisheries Research Institute Mandapam Camp-623 520, Tamil Nadu

Introduction Table.1 : Some uses of molluscs shells

, The molluscs recorded from the world Examples of Out lets I range from 80,000 to 1,00,000, out of which molluscs products 50,000 are gastropods, 15,000 bivalves, 500 Mostly large, Ornamental Whole shells polyplacophora, 400 cephalopods, 130 colorful, relatively used as a shells cheap, plentiful, aplacophora and 5 monoplacophora. There are souvenirs and mostly gastropods, 31,463 marine, 8,765 fresh water and 24,503 land decorations molluscs reported from different parts of the some bivalves including giant world. Humans have valued marine mollusc shells clams since prehistoric times. Shells have been used I for currency, jewellery, ornaments, tools, horns, "Rare" or Few in trade; Collector's games, medicine and as magical or religious specimen expensive; mostly items symbols (Claassen 1998). Even though tropical shells narrow endemics bivalves and gastropods have lost much of their & / or deep water historical meaning as medicine, tools or religious gastropods. symbols, they may be used in even larger Shell crafts Strombus spp, Table lamps, lamp shabes, quantities today. Shell-craft industries in Southeast Cassis spp, domes, dolis, Asia may still use thousands of tons of shells Cyprea spp, garlands, pendents for annually for mother-of-pearl products (Wells Lambis spp, chains, 1989). The ornamental shell trade, which primarily Conus spp, necklaces, ear drops, beats for includes shells exploited for their decorative or Xanchus pyrum the neck, hair rareness value, · is also substantial. The Small shells such pin, fantency flower ornamental shell trade might even have intensified as Cowries spp, sculptures of in recent years with the rise of the Internet. Abbott Oliva spp, Arca gods, pen stand, bangles, (1980) estimated that some 5000 mollusc species spp, Babylonia flower vases , are involved in the ornamental shell trade. spp etc. shell screens for windows and Tourism has become an important door curtains economic activity in many tropical countries. The tourists' interest in 'portable memories' has also Mother of Trochus niloticus Buttons, Inlay brought a curio trade into existence, often involving pearls or I (commercial works, jewellary, gastropod and bivalve shells, corals, shark teeth commercial trochus), Turbo Shell crafts and other parts of marine species ( Poulsen 1995; shells marmoratus - Vorlaufer 1999). Shells seem highly demanded (green snail) and souvenirs because of their varied forms, attractive Pinctada spp. colouring or smoothness. However, they may also Industrial Gaint clam Constituents of be symbols of freedom and leisure. shell (Tridachinidae) pottery glazes; It is difficult to categories shells manufacture of satisfactorily according to their uses as many are floor tiles. collected for several purposes. The main categories are shown in the table -1.

------. -- . . ' . 4~' Shell processing With certain species for example Spider The important centers where the shells shells, Lambis spp, the queen conch Strombus are processed are Pam pan, Mandapam, spp and Giant clams both shells and flesh can be Rameswaram, Thirupalaikudi, Devipattanam, used. Shells of some species have several Mullaimunai and Thondi. Shells are procured from alternative uses for example the entire giant clams Thoothukudi, Cuddalore and Andaman and shell is used in the ornamental trade while the Nicobar Islands. After drying the shells in the open broken pieces are used for jewellary. Ground up yard for 4-5 days, they are soaked in either fresh giant clam shell is used as constituents of pottery and sea >'water for 3-5 days in cement tanks, glazes and manufacture of floor tiles. depending on the size and variety of the shells. This enables the removal of dirt and decayed soft Marine ornamental shell industry part of the animal. Then the shells, are placed in Majority of the gastropod and bivalve the bleaching powder solutions for 24 hrs in species that have been reported all along the cement tanks followed by immersing the shells south east coast of India are known to occur in in castic soda solutions in another tank for 1-2 Ramanathapuram coast. The availability of a hours. Depending on the thickness, colour and f variety of shells in good abundance have led to quantity of the shells they are polished by allowing the development of ornamental shell industry at them to remain in 5% HCL for 10 sec to 4 min. In keelakarai and Rameswaram. Several species of order to remove colours of the shell, shells are shell animals which occur in the Gulf of Mannar soaked in hot palm oil for half an hour. and Palk Bay constitute the raw materials for these The commercial important shells used by industries. Apart from very rare species, 15-20 shell industries of Keelakarai & Rameswaram are important species are regularly exploited for these listed in the table-2 purposes. The methods of exploitation of these shells Table -2: Commercial important shells by shell depend on the size, behaviours and habitats in industries of Keelakarai and Rameswaram. which they occur. This may be divided into 1.) - Species Vernacular name Hand picking 2) Skin diving 3.) Hand dredging Xaneus pyrum Sanku and 4.) By different types of nets viz. trawl, gill Hemifusus pugilinus and dragnets employed mainly to catch fin fishes, Lambis lambis Aiviral Sanku lobster and crabs. A wide variety of shells like Area spp Sippi/Kilinjal chanks, species of Area, Hemifusus, Natiea, Umbonium vestiarium ' Poochi koodu Strombus, Babylonia, Conus, Murex, Harpa , Tibia spp Ezuthani Cymbium etc. form a portion of the by catch in Cypraea spp SozhilMani/Mowri trawl nets operated for shrimps 'and fish. Oliva spp Kovanchu The ecological habitat surrounding Conus spp Vazhvipoo Mandapam-Rameswaram-Keelakarai coastal belt Chieoreus ramosus Yanai Mulli is ideally suitable for growth of a variety of Murex haustellum VeliaiPoodu gastropod and bivalve shell species. The 21 island Cymbium melD Suvappu pathiram system in the Gulf of Mannar provides suitable Harpa spp Sarpa koodu areas serving as breeding ground for many of the Cypraea talpa Anil sozhi gastropod shells which form the important Fusinus spp. Vellai Chavai components supporting the shell industries in this Strombus spp Veranjan region. Babylonia spp Puramuttai Oentalium spp Vellai Mooku Cymatium spp Pillayar Sanku r Volume of Trade Molluscan shell trade A clear picture of the volume of trade in The scale of international trade in shells is difficult to obtain for several reasons, ornamental shell has recently become a subject a) Shell are often combined with other good or of considerable concern; more than 5000 species marine products (especially corals) in official may be involved and international trade in statistics unworked ornamental shell amounts to thousand b) Trade statistics seldom differentiate between of tonnes annually. Many invertebrates other than species, except for commercial or mother of corals are popular in the aquarium trade. Main pearl species, and it is difficult to calculate molluscan species in the trade are Turbo spp., the relative volume of each species in trade, Tridacna spp., and Trochus spp. The Philippines, number of individuals involved; and Mexico, Indonesia, Singapore, Fiji, Sri Lanka, and c) International trade statistics do no include Vanuatu are the major exporters of shells; United domestic trade (example through gift shops States and Japan are the major importers followed in the country of origin) so that export figures by the United Kingdom, Netherlands, France, cannot necessarily be equated with total Germany, Italy, Taiwan, and Canada. exploitation. Giant clams, Tridachnidae, represent an increasingly large proportion of the exports of live Disruption of ecological balance invertebrates for aquarium trade. it is the largest Little attention has been paid to the bivalve in the world. The more brightly coloured consequences of the selective removal of shells Tridachna maxima, T crocea, and T derasa are in the ecosystem as a whole, but problem can more popular ones in the marine ornamental arise in a long.run. Destructive collection trade. Unsustainable exploitation of giant clam practices, over-exploitation, the lack of scientific species has led to the local extinctions of some information on many species collected and threat species such as T gigas in some areas (Hestinga of extinction of target species are the major et. al., 1984). The CITES provides a mean of problems of the marine ornamental molluscs controlling international trade in species trade. It has been suggested, for example that considered to be serious threatened. At present over - collection of the giant triton, Charonia only marine molluscs listed is the giant clam. tritonis which preys on a large starfish, has In India, a notification dated May, 28, July contributed to population explosion of the thorny 21, and December, 5, 2001, the Ministry of starfish Acanthaster planei. Plagues of the Environment and Forest, Government of India has starfish have caused extensive damage to coral included 24 ornamental mollusc species in reef in many parts of the Indo-pacific. Schedule I of the Wild Life Protection Act, 1972. These ornamental molluscs are protected by the Mariculture Act. One way of relieving pressure on stocks Fisheries for the commercial shells exists on wild shells is to use cultivated molluscs in many Southeast Asian and Pacific countries instead. Although mariculture programmes have and in most cases are well documented. been developed for many edible molluscs, they Southeast Asia is the center of the Mother of have only recently been attempted with species pearls and button industries. Taiwan export around used in the shell trade; Strombus gigas, Trochus 30 tonnes of worked mother of pearls and 200 niloticus, Haliotis spp, Pinctada spp and tonnes of mother of pearl articles annually and Tridachinidae Japan has similarly large exports. Marine Molluscan Aquarium Marine gastropods are very beneficial in Sand Conch the reef aquarium. As they burrow and dig through The Sand conch such as Strombus the aquarium substrate, they will clean and aerate canarium and S. marginatus is a hardy member the bottom and will eat perishable organic matter of the Strombidae family. Despite their name, they in your marine aquarium thereby, preventing your are peaceful toward other tank mates. They are tank water from being contaminated. These excellent sand sifter and are very beneficial in the cleaner species are particularly important in reef aquarium. They are hardy algae eater. They controlling algae growth and parasites. Most also love the brown diatoms found on the surface gastropods and bivalves are herbivores but some of live sand beds. They wi" stir and clean upper marine ones are omnivores. layers of the sand bed. As they burrow and dig Habit & Habitat through the aquarium substrate, they clean and Gastropods are nocturnal in habit. They aerate the bottom. are solitarily found near rocky reefs ~ grass beads, Abalone and sandy bottoms around the coastal areas of Abalone such as Haliotis varia is generally Indian Ocean. nocturnal, finding refuge in holes or crevices in Ideal marine aquarium environment the rocks or coral during the day, and coming out Gastropods require a pH value of around to forage at night, using its foot to glide over the 8.10-8.40, and temperature at around 72-80· F, in substrate and coral rubble. The foot attaches very the tank. Stable pH & temperature levels, and firmly, so use extreme caution if attempting to minimal or zero copper and nitrates are desirable remove it from glass or rocks. While its diet is in the aquarium to avert any lethal shocks to the almost exclusively algae, it would benefit from shelled animals in there. Keep ample live rock, supplementation with dried seaweed, lettuce, caves, corals, and sand to hide in and graze upon. spinach, or Spirulina sheets/tablets.

Aquaril:lm Feeding Banded Trochus snail Most gastropods are algae eaters and Trochus snail move very slowly but leave hence keep the aquarium free from unwanted algal nothing behind, eating filamentous algae, slime growth. Most shelled animals are omnivores and algae, green algae, diatoms, and cyanobacteria. scavengers in feeding habit. They are known for Add to this the fact that they often are able to right eating away the meaty bits of brine shrimp, mysis themselves if they fall on their backs. Extremely shrimp, fish, & scallop, and scavenge on detritus hardy, as long as water quality remains good they and fish waste. In the search of food, shelled have a very long life. animals also plough the sand, thereby cleaning and aerating it. Turbo Snail Important Acclimation Information All gastropods are very sensitive to Turbo Snail is a beautiful algae removing changes in salinity and water chemistry from one machine. Like the other members of the Turbinidae aquarium system to another. It is vital to slowly family, the turbo snail has a voracious appetite for acclimatize all shelled animals to your marine algae. Turbo snails are found in crevices and holes aquarium environment using the slow drip within the reefs during the day, and at night they method. The slow acclimation process needs to come out to forage. In the home aquarium, the be done over a minimum time period of at least turbo snail prefers ample hiding places among the two hours to avoid your shelled animals dieing live rock for the day time, and will come out to over the first few days from water chemistry shock. graze on algae on the rock and glass during the evening hours f Fig.1: Marine ornamental molluscan species inAquria

Strombus marginatus Lambis lambis

Haliotis varia Trochus radiatus

Babylonia spirata . Netita spp.

Turbo intercostalis Bursa spinosa' Apart from above mentioned species, other gastropods such as Babylonia spp., Nerita spp. Natica spp. Bursa spp. Hemifusus spp. Nassarius spp. etc. can also be maintained in aquarium.

References:

Abbott R.T. 1980. The Shell Trade in Florida: Status, Trade and Legislation. Special Report 3. TRAFFIC (USA), Washington, DC.

Claassen C. 1998. Shells. Cambridge University Press, Cambridge, UK.

Hestinga G, Perron E, Oranko. 1984. Mass culture of giant clams (Family Tridachinidae) in Palau. Aquacultur~. 39:197- 215.

Vorlaufer K. 1999. Tourismus und informeller Sektor. Geographische Rundschau 51 : 681-688.

Wells S.M. 1989. Impacts of the preciouS shell harvest and trade: conservation of rare or fragile re sources. In: Caddy J. (ed} Marine InW::ttebrafe Fisher{es; Their Assessment and Management. JohnWiley and Sons ~ New York, pp.443-454

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