VISTAS Vol. 7, No. 1, 2018, pp. 12-15 ISSN: 2319-5770, e-ISSN 2394-1138

A STUDY ON THE BIODIVERSITY OF GASTROPODE & BIVALVE MOLLUSCS IN MUNAKKAL & SNEHATHEERAM BEACHES OF DISTRICT Anis K.V.* *Department of Zoology, St. Joseph’s College (Autonomous) Irinjalakuda, Thrissur 680121, , India. ABSTRACT Diversity of Gastropod & Bivalve molluscs in Munakkal & Snehatheeram beaches was assessed. The samples were collected for a period of 3 months and diversity was analyzed. Bivalves belonging to four different orders were identified. They are veneroida, Mytiloida, Ostreoida, & Pectinoida. Identified Gastropods were included in the Orders , & .

Key words: Bivalves, Gastropods, Veneroida, Mytiloida, Ostreoida, Pectinoida, Neogastropoda, Littorinimorpha,Caenogastropoda

INTRODUCTION Molluscs, Commonly called the ‘shelled fishes’ are among the best known of all invertebrate . is the second largest phylum, next to Arthropoda. They are highly adaptive and they have successfully colonized both aquatic & terrestrial environments. Bivalvia is group of bilaterally symmetrical and laterally compressed molluscs, with paired right and left mantle lobes and a bivalve calcareous shell. Bivalvia is the second largest group of phylum Mollusca, comprising an estimated 15,000 odd species. Bivalves are especially adapted for exploiting the benthic habitat, where they are safe from predators. A perfect understanding of the bivalve diversity of the coastal system is an essential prerequisite for implementation of sustainable utilization of bivalve resources and for adopting suitable conservation measures the gastropods (snails and slugs) are by far the most numerous molluscs in terms of classified species, and account for 80% of the total. The class has an extraordinary diversification of habitats. Representatives live in gardens, woodland, deserts, and on mountains; in small ditches, great rivers and lakes; in estuaries, mudflats etc. Bivalve molluscs are used as bio indicators to monitor the health of aquatic environments in both fresh water and the marine environments.

The study was conducted to identify Gastropod and Bivalve Molluscs in Munakkal and Snehatheeram beaches of . Eleven species of Molluscs were identified and they are in the orders Veneroida, Mytiloida, Pectinoida, Ostreoida, Neogastropoda, Littorinimorpha, Caenogastropoda respectively.

STUDY AREA The Munakkal beach is lying in theAzhikode village in Thrissur district. The study site is very near to Kodungallur Azhikode estuary. The Kodungallur- Azhikodeback waters, which is an extension of theVembanad backwaters in northern region is an ideal habitat for several species of shellfish. The beach is filled with fine VISTAS Vol. 6, No. 1 ● 13 grained sand. Snehatheeram beach or Love Shore beach is in of Thrissur District in Kerala State of India. It lies on the coast of Arabian Sea.

OBJECTIVES 1. To study the diversity of Gastropod and Bivalve molluscs seen in Munakkal and Snehatheeram Beaches of Thrissur district

2. To identify molluscs to species level using taxonomic keys.

METHODOLOGY The samples (Shells & whole specimens) were collected by hand picking in a transect of known area. Fresh specimens were preserved in formalin and brought to the laboratory for identification. The Gastropods are identified mainly based on the shell morphology, with reference to taxonomic keys. The shells, which are identified, are dried and cleaned.

The external features of shells are noted and similar ones are grouped. Photographs were taken using cameras at the spot. A conversation with the fisherman of both beaches provided some extra information of the abundance of shells. The shells caught in fish nets are return to the sea at the time of fishing.

RESULT & DISCUSSION

The Species identified are come under two classes: Gastropoda & Bivalvia. In the present study six & five varieties of Gastropod & Bivalve molluscs were collected and identified from two beaches respectively. They fall under seven different orders. They are veneroida, Mytiloida, Ostreoida, & Pectinoida of bivalves and Neogastropoda, Littorinimorpha & Caenogastropoda of gastropods.

Fig.1: Class Bivalvia & the orders

Fig.2: Class Gastropoda & the orders 14 ● ISSN: 2319-5770 e-ISSN 2394-1138

GASTROPODS:- BIVALVES:-

1. tribulus 1.Venerupis decussate

Order Neogastropoda Order Veneroida

2. spirata 2.Katelysia marmorata Order Neogastropoda Order Veneroida

3.Babylonia zeylanica 3.Mytilus edulis

Order Neogastropoda Order Mytiloida

4.Ficus subintermedius 4.Aequipecten opercularis

Order Littorinimorpha Order Pectinoida

5.Phalium cancliculatum 5.Ostrea edulis

Order Caenogastropoda Order Ostreoida

6.Turritella attenuate

Order Caenogastropoda

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