Turban shells on intertidal and subtidal areas in Andrew Bay are composed of 12species belonging to genus Turbo Linnaeus 1758 of family Turbinidae falling under the order Archaeogastropoda collected from field observation in 2014, were identified, using liquid-preserved materials and living specimens in the field, based on the external characters of shell structures. The specimens comprised Turbo argyrostomusLinnaeus, 1758, T. articulatusReeve, 1848, T. bruneus(Röding, 1798), T. chrysostomusLinnaeus, 1758, T. cidarisGmelin, 1791, T. cinereusBorn, 1778, T. crassusWood, 1828, T. fluctuosusWood, 1828, T. imperialisGmelin, 1791, T. intercostalisMenke, 1846, T. petholatusLinnaeus, 1758 and T. radiatusGmelin, 1791. The distribution of turban shells in intertidal and subtidal zone of Andrew Bay was studied in brief. Moreover, the habitats and utilization of turban shells found along the Andrew Bay were also described.

Keywords: Andrew bay, distribution, habitats, rakhine coastal region, turban shells, utilization

The Turbinidae are tropical gastropods with the majority of species found in the Indo-pacific region; only ten species are present in the Western Central Pacific.¹ There are 2 genera, Astralium and Turbo and 10 species, namely A. calcar (Linnaeus, 1758); T. argyrostomus Linnaeus, 1758; T. bruneus (Röding, 1798); T. chrysostomus Linnaeus, 1758; T. cinereus Born, 1778; T. coronatus Gmelin, 1791; T. crassus Wood, 1828; T. marmoratus Linnaeus, 1758; T. petholatus Linnaeus, 1758 and T. setosus Gmelin, 1791 in the family Turbinidae. In this region, the turban shells, Turbo Linnaeus, 1758 is probably the most important genus of this family. Many authors have reported significant variations in spatial and temporal distribution and abundance of some species within this family.^2,3 These species normally present in large numbers, particularly within the shallow near-shore rocky substrate and coral reef ecosystem.^4–9

In Myanmar, there were currently very few studies dealing with the biology and ecology of these species except taxonomic work of Soe Thu 10. There are 9 species of Turbo, namely T. petholatus reevei Phillippi, 1844; T. argyrostomus Linnaeus, 1758; T. chrysostomus Linnaeus, 1758; T. cornutus Lightfoot, 1786; T. excellens Sowerby, 1855; T. marmoratus Linnaeus, 1758; T. cinereus Born, 1778; T. porphyrites Gmelin, 1791 and T. intercostallium Menke, 1829 (T. intercostalis Menke, 1846) had been reported from the three Coastal Regions of Myanmar.¹⁰ Likewise, 2 species of Turbo, namely T. argyrostomus Linnaeus, 1758 and T. cinereus Born, 1778 had been reported by Naung Naung Oo¹¹ based on morphological and some ecological features collected from various coastal areas of Mon State.

Much information such as their distribution pattern, habitat preferences and habitat range were still remained unknown. The objective of the current study was to determine the spatial variations in abundance of turban shells population in their natural habitat. This information is very important for conservation and for better management of this species.

Some turban shells were collected in the forms of drift and live specimens living in intertidal and shallow subtidal areas such as Geik Taw, Pearl I., Thanban Gyaing, Abae Chaung, Thanbayar Gyaing, Mayoe Bay, Kathit I., Thabyu Gyaing, Ponenyat Gyaing, Kwinwine Gyaing, Kyauk pone gyi hmaw and Maung shwe lay Gyaing around the Andrew Bay, Rakhine State (Figure 1) during the field trip in 2014.

Figure 1 Map showing the collection sites of Andrew Bay in Rakhine Coastal Region.

All collections were preserved in 10% formalin in seawater. The epifaunas were removed by soaking the shells in a solution of caustic soda and then cleaned, washed, dried, and ready for storage, they are lightly rubbed with a small amount of oil applied with a brush to make them fresh-looking in a slight luster to the surface, and aid in presenting the delicate colouring for further study.

All voucher specimens were deposited at the Museum of the Department of Marine Science, Mawlamyine University (MLM.MS). Zoogeographical distribution of each species was prepared with the data from the literature available. Ecological notes and associated species of these molluscs were also recorded in the field.

The spatial variations in abundance of turban shells surveys conducted from 12 collection sites at Andrew Bay and its vicinity in Rakhine Coastal Region. In this study, a total of 12species of turban shells were observed from different habitats at intertidal and shallow sublittoral zones, to a depth of about 20m or more. This systematic account follows the identifying set out by Poutiers et.al in detailed^1,3,12–19 (Table 1)(Figure 2).

Figure 2 Map showing the collection sites of Andrew Bay in Rakhine Coastal Region.

Shells are thick, often heavy, turbinate to conical (occasionally flattened) in shape. Outer sculpture is very variable, often spiral to nodular. Periostracum well developed to absent. Aperture is variously rounded, without a siphonal canal, nacreous inside. Inner lip is smooth. Umbilicus present, at least at juvenile stages. Operculum is strongly calcified externally, its inner layer corneous, usually showing spiral coiling with a subterminal or central nucleus. Head with a short, mid-ventrally split snout, and a pair of long tentacles, the eyes on stalks at their outer bases. Foot is large and ovate, sometimes anteriorly truncate, with a fleshy ridge on either side bearing tentaculate processes.

Turban shells mainly living in shallow waters of warm temperate and tropical seas, especially on rocky and coral reef habitats. The local distribution and habitat of each turban species are shown in Table 2 and 3. These are herbivorous animals, feeding on small epibenthic algae and vegetable detritus. Turbans (especially the larger species) are commonly collected in the Indo-West Pacific, both for their edible flesh and nacreous shell. They are locally valued for food and some are sought for mother-of-pearl or for carving ornaments. Green turban, Turbo marmoratus Linnaeus, 1758 with massive shells possessing shiny iridescent pearl layers, used in the manufacture of buttons, lamp-shades and other fancy articles, support fisheries of importance in Myanmar.^20,21

Collected locally for food and shell craft on the Indochinese peninsula. In seaside villages of Japan, children put the operculum in vinegar because it makes a circular movement as it gradually dissolves.¹ Turban shell support an important recreational fishery along the Andrew Bay that provides income for small businesses such as bait and tackle shops, restaurants, hotels, boat rental shops, marinas, and many others. The shells are found on the submerged rocky or coral reefs at moderate depths. In recent years, heavy commercial exploitations have locally depleted populations. Efforts are expected in the future to produce juveniles in hatcheries and introduce turbans in areas in which they have become extinct or areas currently poor in fisheries resources.

The distribution of turban shells presented by the data from the 12collection sites of intertidal to subtidal rock and reef areas in Andrew Bay is that abundance is moderate. This is particularly true when it is considered that the 12 sites were spread over a wide area in a region known for high biodiversity. In the present study, Kyauk pone gyi hmaw site had higher abundance than other 11collection sites. A total of 12species of turban shells were recorded with their habitats of which 10species in Kyauk pone gyi hmaw; 8species in Kathit Island, Ponenyat Gyaing and Kwinwine Gyaing; 7species in Pearl Island and Maung shwe lay Gyaing; 6species in Geik Taw and Thabyu Gyaing; 5species in Abae Chaung and Thanbayar Gyaing; and 4species in Thanban Gyaing and Mayoe Bay, respectively (Table 2).

Many aspects of the shell morphology in turban shells are associated with physical stabilization in diverse ecological settings. Shells are moderately large, solid and heavy, turbinate in shape with length usually greater than width. Spire is well developed, pointed, whorls strongly convex and with angular shoulders. Outer sculptures are variable, with rounded, unequal spiral cords and many fine scaly axial threads, most developed on the interstices of cords. Operculum is nearly circular in outline, with a sub central nucleus and a convex, smooth external surface. Outside of shell is variable in colour and pattern. The distribution of turban shells in Andrew Bay moderately disperses along the shallow coral reefs and rocky shores. Local people frequently collected by Turbinidae in the area, mainly for food. The operculum is well known in shell jewellery under the name “cat’s eye”.

I am indebted to Dr Aung Myat Kyaw Sein, Acting Rector of Mawlamyine University and Dr Mie Mie Sein, Pro-Rector of Mawlamyine University, for their encouragement and supports in preparing this work. I am very grateful to Dr San Tha Tun, Professor and Head of the Department of Marine Science, Mawlamyine University, for his valuable suggestions and constructive criticisms on this study. I would like to express my sincere thanks to colleagues of Andrew Bay Observation Group, Department of Marine Science, Mawlamyine University, for their kindly help me in many ways during field trips. Many thanks go to Daw Lwin Lwin, Retired Lecturer of the Department of Marine Science, Mawlamyine University, for her assistance in preparations of the manuscript. I would like to thank my beloved parents, U Win Maung and Daw Than Than Aye, for their physical, moral and financial supports throughout this study.

The author declares that there are no conflicts of interest in relation to this article.

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