PREFACE
I have always been fascinated by the sea. I remember my early days, when I used to spend my vacation time to see the fisherfolk who used to collect clams from the sand. I tried to imitate them several times, without success. Over a period of time I realized the secret behind it. That was the time when I really started understanding the elusive nature of these soft bodied animals and since then shell observation has been my passion. When I visited lots of sea shores around my country, and my passion turned to the field of research. For the last 15 years, I have collected considerable data of sea shells along various coasts of India. Among the various groups, Cowries, Cones, and Clams are my special interest.
I am fortunate that my family members always encouraged my hobby. I have made attempts to cover common species which one comes across usually during seashore visits. I am confident that this blog will be an useful guide to graduate and postgraduate students of zoology, since a number of species illustrated here form part of their syllabus.
The exact localities are deliberately not provided to avoid over-exploitation. Viewers suggestions, comments and additional information will help to improve and update the available data.
With all respect,
FIROZ AHAMMED. A
(Director)
ABOUT ME
Born in Alleppey to Y. A. Abdullah and Haleema, I was educated in the Government Mohammedan Higher Secondary School and NSS College in Alappuzha. I have an IT diploma in computers. Collecting sea shells has been my passion since childhood. Apart from the wonders of the sea, I also collect greeting cards, key chains, coins and currencies of various countries and feathers of different birds (my collection includes the feather of an ostrich too!).
Armed with a vast collection of sea gifts, I have conducted over 15 exhibitions in various parts of Kerala. One of my dreams is to set up a museum that will explain the wonders of the sea to the public and the young generation. I am also ready to conduct exhibitions of my collections wherever people will be interested in seeing the rare articles I have in my possession.
I have a special word of thanks to the media which has wholeheartedly supported me in all my efforts. The print media, including the German newspaper Rheinische Post, national dailies like The Indian Express and The Hindu and Malayalam dailies, have given me vast coverage in their pages. The electronic media, without exception of any channel, too have covered my exhibitions regularly. I take this opportunity to thank all of them and to appeal for continued support.
However, I am sad about one fact. There has been little support from the Government here. I had submitted a request for help to set up a sea museum, but there has been no positive response so far. I am humbly requesting all those who read this to kindly help in whichever way they can, either by sharing their collections or informing me from where I can enhance my collection and also by helping me to conduct more exhibitions and take my collection to more people around the world.
Those interested in contacting me can call me on 91-98474-30401, 91-9895050515 or by emailing me at ahammedfiroz@yahoo.co.in and firozseagift@gmail.com.
About My District – “Alappuzha”
Alappuzha, formerly known as Alleppey is popular under the sobriquet “ The Venice of the East”, due to the presence of criss- cross canals and bridges. Blessed with the Iullaby of the Arabian Sea and the fresh breeze from the lakes make the district a unique gift of the nature and it came into being as a district on the 17 th of August 1957. It became the 9th Revenue District of the State. The district was formed by dividing neighbouring Kollam and Kottayam districts.
INTRODUCTION
Collecting shells has been a pastime of many, young & old, for centuries. It is only when collecting becomes a passion rather than a pastime that the finest examples are sought, and the subject researched in detail. Such is the case with this collection, one of the countries finest, assembled by local shell collector Mr. Firoz Ahammed. A focusing on families of marine gastropods - Cowries, Cones, Conches, Harps, Volutes and Olives - - the collection includes numerous species listed in the registry of World Record Size Shells. Firoz has made a portion of his collection available for public enjoyment in this exhibition. Most of the shells on display are those of gastropods, that is snails. Gastropods form one of the seven classes of the phylum Mollusca.
The word "Mollusk" derived from the Latin "Mollis" meaning "Soft", denotes a large, divers group of soft bodied animals who occupy nearly every region of the world. Numbering at least 50, 000 living species, mollusks are second in number of species only to the arthropods, which includes insects. Mollusks may live in terrestrial, aquatic or marine habitats, although marine dwelling mollusks outnumber the others. They may be carnivorous or herbivorous, predator or prey, or-often-both. Most, but not all, mollusks have shells. The two largest classes are the gastropods, which are single - shelled animals. And the bivalves, which have two shells. While the exhibition focuses on gastropods, a few interesting bivalves are also displayed. Examples of mollusks without shells are the octopi & squids.Regarding the Mollusca themselves, despite the wide diversity of body forms, the groups of animals we classify as Mollusca share the following unique features....
radula ( absent in Bivalvia )
mantle capable of secreting a calcium carbonate based shell or spicules
mantle cavity
ctenidia (specialized gills having countercurrent oxygen exchange)
osphradia (chemosensory epithelia organs)(absent in Monoplacophora & Scaphopoda)
pericardium around the heart (not around heart in Scaphopoda)
mesodermal origin of pericardioducts
rhogocytes (pore cells) associated with the nephridia (kidneys)
tetraneury (two pairs of main longitudinal nerve bundles)
intercrossing dorsoventral muscles
crystalline style and associated ciliated midgut digestive organs
esophageal pouches
broad creeping sole or narrow hydrostatic foot
large ventral pedal glands that secrete mucus
ANATOMY
The body of the mollusc generally consists of five major parts i) the foot, ii) head, iii)visceral mass, iv) mantle , and v) the shell.
i) FOOT : A highly muscular organ used for locomotion by the animal. Different molluscs have different types of foot. The type of locomotion and substratum are responsible for the development of different types of foot.
ii) HEAD : Situated at the anterior end of the foot, it bears a pair of eyes and a pair of tentacles.
iii) VISCERAL MASS : Contains the digestive, excretory, circulatory and genital organs. The entire mass is covered by the mantle. The space between the mantle and the animal body is known as the mantle cavity.
iv) MANTLE : Is responsible for the formation of the shell. The secretion of the mantle forms the shell.
v) SHELL : Is made up of Calcium Carbonate. Each species has its own shell pattern, structurally as well as morphologically.
CLASSIFICATION OF MOLLUSCA
According to the most recent classification, the Phylum Mollusca is divided into sub-phyla : i) ACULIFERA – with various kinds of spicule-like structures on the mantle or plated shells (e. g. chitons), ii) CONCHIFERA – characterised by shells (except those few which have lost the shell secondarily in the course of evolution).
The Mollusca are classified into six major classes:
i) MONOPLACOPHORA (Neopilina galathaea)
ii) AMPHINEURA (Chitons)
iii) BIVALVIA (Clams)
iv) GASTROPODA (Cones, Cowries, et.)
v) SCAPHOPODA (Tusk shells)
vi) CEPHALOPODA (Nautilus, Squid, Cuttlefish, Octopus)
The three extinct classes are – ROSTROCONCHIA, STENOTHECOIDA, MATTHEVA.
i) Class MONOPLACOPHORA: This was supposed to have become extinct 350 million years ago. However, in 1957, a few living specimens were recovered from Costa Rica and the species was named Neopilina galathaea (THE MACDONALD ENCYCLOPEDIA OF SHELLS, 1980).
ii) Class AMPHINEURA: Mouth and anus at opposite ends of the symmetrical and more or less elongated body; mantle provided with numerous spicules embedded in a cuticle.
iii) Class BIVALVIA: The shell is made up of 2 valves joined to each other by a ligament and a hinge. There are about 20,000 living species of bivalves. Most of these are marine and live on the sea bed or burrow in sand. Some of the bivalves have thread-like structures called byssus threads by which they anchor themselves to rocks. (e.g. Mytilus or mussels).
iv) Class GASTROPODA: This class consists of more than 80,000 species and is subdivided into 3 subclasses.
Subclass: Prosobranchia (Gills present in front of the heart)
Subclass: Opisthobranchia (Rear gills)
Subclass: Pulmonata (Gills absent, with the pallial chamber converted into a “lung” or pulmonary sac).
The first two subclasses are exclusively marine, while pulmonates live on land or in fresh water.
v) Class SCAPHOPODA: This class includes tusk shells which are exclusively marine and number about 1000 species. The shell is open at both ends. It usually remains buried in sand.
vi) Class CEPHALOPODA: Consists of about 700 living species and 10,000 fossils species. These are exclusively marine animals. This class is again subdivided into 2 subclasses: Nautiliodea (with external shell, e.g. Nautilus) and Coleoidea (shells are internal, reduced or absent, e.g. squid, octopus, cuttlefish which are the most active and fast moving among the molluscs).
METHODS OF CLASSIFICATION
Broadly there are two system of classification.
a) Classification based on the structure of the Radula
Radula or the tongue is a ribbon – like membrane with transverse rows of denticles on the upper side. Different molluscs have different feeding habits, namely herbivores, carnivores, scavengers, detritusfeeders, etc., and according to these feeding habits, the Radula is also modified into various types such as hystricoglossate, rhipidoglossate (Trochus), docoglossate (Patella), ptenoglossate (wentle trap), taenioglossate (conches), rachiglossate ( Murex ) and toxoglossate (cones).
Rhipidoglossate and hystricoglossate Radula are useful for scraping algae off rocks. The taenioglossate Radula is characteristic of omnivorous molluscs. Carnivores have the rachiglossate type of Radula. Toxoglossate Radula, characteristic of cones, has a harpoon-like structure to kill or paralyse the prey.
Denticles on the Radula of each species have a specific formula and comprise the rachidian tooth, lateral denticles and marginal denticles.
The changes in the radular structure give clear evidence of evolution from the lower algal scrapers or herbivores (hystricoglossate Radula with numerous denticles) to the predatory molluscs (toxoglossate Radula of cones which have developed harpoon-like structures attached to a venom sac).
b) Classification based on shell structure
The shell, as mentioned earlier, is secreted by the mantle. The outer layer of the shell is the periostracum and the inner layer is the nacre or mother-of-pearl. The periostracum is made up of organic material and the remaining shell is made up of calcium carbonate. Two forms of crystallized calcium carbonate are usually observed in the cross-section of the shells. CALCITE : Rhombohedral, sclenohedral or prismatic crystals in trigonal system. ARGONITE: Elongated, prismatic crystals with rhombic system. Individual species have their own unique shape and colour pattern which makes field identification easy.
HABITAT
Molluscs generally occur in three oceanic zones, viz. benthic, pelagic and littoral. The maximum number of species occures in the littoral zone. Very few are benthic or pelagic. The littoral zone is again subdivided into various zones such as the supralittoral zone (strip of beach above the high tide mark), mesolittoral zone (intertidal zone), infralittoral zone (slope of beach always remains submerged under water) and circalittoral zone ( lowest level down to which green algae can survive).
Each species has a specific pattern of distribution, e.g., Littorina, Natica, Trochus, Conus, Bursa, Nassarius and Drupa occur in the mesolittoral zone. Telescopium occurs in mangroves near high tide mark, whereas abalones, Tibia and conches occur in deeper water (circalittoral zone). Janthina are pelagic shells. The predominance of a species at a place is mostly dependent on the feeding ground, temperature and the water quality. Depending on the substratum, the various habitats where shells occur can be classified as sandy beaches, rocky shores, mud-flats, mangroves and coral reefs.
1) Sandy Beaches
In this habitat, shells are adapted for burrowing. Most of the bivalves such as Donax, razor clams and Arca take refuge in sand. Oliva shells and moon snails are also common on sandy beaches. It may be difficult for a novice to collect shells from sandy beaches as the shells remain buried.
2) Rocky Shores
Molluscs are abundant on rocky shores, which provide good refuge for rock shells, dove shells, frog shells, chitons, limpets, whelks, periwinkles, etc. low tide is a good opportunity to search for rock dwellers in shallow rock pools, since most of them come out for feeding in shallow pools. Rock crevices not only support molluscan fauna but also various other invertebrates like coelenterates, sea stars, sea urchins, feather stars, crabs, etc.
Edible oysters and mussels also occur on rocky shores. Some bivalves excavate rocks to form burrows.
3) Mangrove Swamps
Mangroves are salt-tolerant, self-maintaining forest ecosystems of tropical and subtropical intertidal regions. They occur along sheltered shores, estuaries, tidal creeks, backwaters, salt marshes and coastal mud-flats. Mangroves have been considered as a highly productive ecosystem that provides a wide range of valuable forest products, maintains estuarine water quality and plays a vital role in the life cycle of many fish and shell fish. Dense mangroves with their pneumatophores and stilt roots provide good refuge for oysters and other molluscs. The mangroves also play a crucial role in holding coastal soil and silt, and preventing erosion.
It is because of their commercial exploitation for fuel, fodder, timber, agriculture, fishing, medicines, etc., that they are endangered.
4) Mud-flats
These are formed mainly by siltation along with many other factors. Very few species of molluscs live on mud-flats.
5) Coral Reefs
Coral reefs are unique among the various marine habitats. The world’s most beautiful shells occur in coral reefs. Beautiful cowries, delicate nudibranches, deadly cones and massive helmet shells are a few among the widely sought molluscs seen here. The world’s largest bivalve Tridacna gigas and the world’s largest gastropod Cypricassis rufa flourish in coral reefs. Unfortunately, very few coral reefs remain along the Indian mainland coast. Okha, Pirotan, Lakshadweep, Andaman and Nicobar Islands are some of the Indian coral reefs and coral islands. Coral reefs provide shelter to numerous species of vertebrates and invertebrates. Among the invertebrates, Phylum Coelenterata is responsible for the formation of coral reefs. The small polyps of the coelenterates have a strong affinity for calcium. These polyps, under ideal conditions such as water temperature between 20oC – 22oC, adequate light, hard substrate, clear and well oxygenated water and adequate supply of planktonic food, form coral reefs. Coral polyps show symbiotic association with the blue-green algae Zooxanthella.
Heavy monsoon, cyclones, and predators like “crown-of-thorns” sea star are some of the natural disasters for coral reefs. An explosive growth in the crown-of-thorns sea star (Acanthastar planci) devastated some of the coral reef islands in the Australian Great Barrier Reef. A possible reason for the population explosion of this sea star may be the over-exploitation of Triton shell which is its natural predator. Siltation, fertilizers and pesticides, sewage, oil refining, tourism, mining for limestone, illegal coral trade and fishing are some of the human pressures on this highly vulnerable ecosystem.
PROVINCES
In the mid-nineteenth century, S.P. Woodward illustrated the distribution of shells using a map of zoological provinces, namely :
1. Indo - Pacific 2. Japonic 3. Australian 4. South Africa 5. West African
6. Mediterranean 7. Californian 8. Arctic 9. Transatlantic 10. Caribbean
11. Patagonian 12. Magellanic 13. Peruvian 14. Panamic 15. Boreal
16. Alutean
INDO-PACIFIC PROVINCE
This is the largest province which comprises the Indian Ocean and most of the Pacific Ocean. It includes the Philippines, Indonesia, Indian Ocean, Taiwan, Papua New Guinea, New Caledonia, Easter Island, Marquesas Island, western and southwestern Pacific, China Sea, northwestern Australia, Mauritius, Sri Lanka, Bay of Bengal, Gulf of Oman, Red Sea and Hawaiian Islands.
The warm waters of the Indo-Pacific province provide refuge for the most colourful among molluscs. The maximum number of molluscs occur in this province. Cowries, cones, mitres, drupes, volutes, olives, conches, terebrids, etc., are abundant here.
The three oceans around the Indian subcontinent make it one of the richest and diverse habitats for molluscs. The mud-flats of Okha, sandy beaches of Konkan, rocky shores of southeast India, coral reefs of Andaman, Nicobar and Lakshadweep Islands, and the mangroves of Sunderban and Andamans provides highly varied habitats. Hence the molluscan fauna of India is far more rich than that of many other parts of the world.
PRESERVATION OF COLLECTED SPECIMENS
It is very essential to preserve our collection. Shells without animals can be preserved easily, just by washing with water to remove sand and mud. But to preserve shells with the animal is difficult becuase most of the animals, when caught, retract into their shells. The simplest method to remove the animal from the shell is to keep the shell in a bottle of fresh water and close the mouth of the bottle tightly. After a few hours, the animal will be asphyxiated and it should then be removed from the shell. The shell should be washed and dried. Another method is to bury the entire shell in sand and let all the material decompose for a period of 15-20 days. Then remove the shell and wash it.
Never wash the shell in strong acid (hydrochloric acid) as the acid can damage the outer glossy layer. In fact, this method is not recommended for beginners. Wash the shell in dilute acid to remove the periostracum and to expose its true colours. Then transfer the shell to fresh water and dry. After drying the shells, identify and put in separate plastic boxes or plastic bags. Do not forget to write the collection data, i.e., locality, type of habitat, date of collection, name of collector, and the identification of the species.
ECONOMIC VALUE OF SEA SHELLS
The first and most important use of molluscs is their place in our diet. Many species of abalones, chanks, cockles, oysters, limpets, cowries and littorina are edible. Tiger cowries are eaten as a delicacy in Japan and the Philippines. Several other species like Cantharus, Katelysia and Tridacna are eaten by local people and fisherman. Shells were used as currency in Asia, Africa and Malaysia. These were Cypraea monita and C. annulus. Commercially important dyes are prepared from Murex shells. Besides, shells are also used in the shellcraft industry. Various decorative items, jewellery and other artifacts are prepared from glossy mother-of-pearl.
shell grit is also used in poultry food since it is a rich source of calcium. The pearl industry has always flourished in India. Nowadays pearls are cultured artificially. Besides all these uses, cone venom has tremendous pharmaceutical potential.
ABOUT THE EXHIBITION
Shells delight and fascinate us in the visual combination of shape and color. Smooth or textured, symmeetrical or not, single - hued or bearing the most complex and astounding patterns of markings, shells treat us to a remarkable display of nature's art.
THE NATURE OF THE SEA
Sea water tastes salty because it has various substances dissolved in it, including a large proportion of Common Salt ( Sodium Chloride). Every litre of sea water contains around 35g of dissolved solid including Nitrates, Phosphates and trace elements needed for plant growth. Sea water also contains dissolved gases, such as Carbon dioxide which plants need to grow and Oxygen which plants and animals need for respiration. So sea water is an ideal life - support system.
KINGDOM OF THE DEEP
Almost three quarter of our planet is covered sea water, forming the single largest home for life on earth. Living in sea was is easier in some ways than living in air. So a tremendous variety of animals and planet lives in different oceans, from the sunlit surface to the deepest, darkest ocean trenches.
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