The Population Study of Keyhole Sand Dollar Echinodiscus Truncates (Echinoidea: Astriclypeidae) in the Intertidal Zone of Penang National Park, Malaysia

Sim Yee Kwang1, Masthurah Abd.1 & Khairun Yahya2
1Centre For Marine & Coastal Studies (CEMACS), Universiti Sains Malaysia, 11800 USM Penang, Malaysia.
2School of Biological Sciences, Universiti Sains Malaysia, 11800 USM Penang, Malaysia.
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Summary of Research (USM Short-Term Grant; Aug 2014 - Aug 2016)

Sand dollar belongs to the class Echinoidea, one of the five classes of Phylum Echinodermata which are marine benthic animal, and therefore all their activities and adaptations are related to ocean bottom (Hyman, 1955). The Echinoidea are either globular, oval or discoid shape with an endoskeleton shell or test, oriented with the oral surface downward. Irregular echinoids are considered a suspension feeder because sand dollar feed on suspended organic particulate matter in the water currents. Sand dollar also play an important role in reworking the sediments and regeneration of nutrients in the substrate through their feeding activity since they are deposit feeders, which process fine organic matter that settles on the seafloor (Kang et al., 2007). Animal from family Astriclypeidae have various specialized podia, spines, cilia, tube feet, mucus-secreting glands and the pedicellariae and a small pincher like organs with moveable jaws that involved in the feeding.

In general, sand dollars are deposit feeders and able to process fine organic matter that settles on the seafloor. This is the reason why this animal is important to the environment, in the sense that they rework the sediments and regenerate nutrients in the substrate through their feeding activity. Besides that, some organisms occurred in the sand dollar’s beds because the sand dollar stabilized the substrate by curtailing the erosion of sand and also provided shelter from predators (Merrill & Hobson, 1970).


This study will be designed to investigate the population of keyhole sand dollar, Echinodiscus truncates in the intertidal zone of Penang National Park. A numbers of sampling will be planned to gather and collect data on the abundance for population of sand dollar according to tidal and monsoon. In this study, biometric parameters of sand dollar such as height, width, test and margin thickness, total wet weight and length of radius, lunule and petaloid will be measured and used for statistical analysis.

This is the preliminary complete research to study on the annual population pattern of keyhole sand dollar, Echinodiscus truncatus in the intertidal zone of Teluk Aling, Penang National Park. We hope to determine and understand the associated environmental factors leading to the population changes of E. truncates in Penang National Park with the particle size, organic matter and water qualities collected from the sampling locations which may produce the useful information for the aquaculture activities here.

This preliminary study also aims to classify and predict the environment healthy condition of Penang National Park with the data collected due to sand dollar is important to the environment; in the sense that they rework the sediments and regenerate nutrients in the substrate through their feeding activity. Besides that, some organisms occurred in the sand dollar’s beds because the sand dollar stabilized the substrate by curtailing the erosion of sand and also provided shelter from predators.
 
References:
Hyman, L.H. (1955). The Invertebrates: Echinodermata: The Coelomate Bilateria. Volume IV. McGraw-Hill Book Company, Inc. New York. pp.413-589.
Kang, D.H., Yang, H.S., Park, H.S. & Choi, K.S. (2007). Use of plate growth measurement for the estimation of skeletal growth of two sand dollars, Astriclypeus manni (Verrill 1867) and Clypeaster japonicus (Döderlein 1885), in Jeju, Korea. Plankton & Benthos Research 2(2): 77-82.
Merrill, R.J. & Hobson, E.S. (1970). Field observations of Dendraster excentricua; a sand dollar of western North America. American Midland Naturalis 83: 595-624.