BIODIVERSITAS ISSN: 1412-033X Volume 17, Number 1, April 2016 E-ISSN: 2085-4722 Pages: 55-60 DOI: 10.13057/biodiv/d170108 The diversity and distribution of Holothuroidea in shallow waters of Baluran National Park, Indonesia ARIF MOHAMMAD SIDDIQ, TRI ATMOWIDI ♥ , IBNUL QAYIM Department of Biology, Faculty of Mathematics and Natural Sciences, Bogor Agricultural University. Jl. Raya Darmaga Bogor 16680, West Java, Indonesia. Tel./Fax. +62-251-8622833,  email: atmowidi@gmail.com Manuscript received: 26 December 2015. Revision accepted: 28 January 2016. Abstract. Siddiq AM, Atmowidi T, Qayim I. 2015. The diversity and distribution of Holothuroidea in shallow waters of Baluran National Park, Indonesia. Biodiversitas 17: 55-60. A study of the diversity and distribution of sea cucumber (Holothuroidea) in shallow waters at Baluran National Park, East Java, Indonesia was carried out from July until September 2015. The method used in this study was systematic transect in low tide condition. Samples were collected by hands at intertidal sites. Identification of sea cucumber species based on morphological ossicles. Twenty one species of Holothuroidea belonging two orders and four families were found in this study. The most dominant family found was Holothuriidae (16 species), followed by Stichopodidae (2 species), Synaptidae (2 species), and Chiridotidae (1 spesies). Four species (Holothuria olivacea, H. verrucosa, Labidodemas rugosum, and Chiridota smirnovi) are new record for Java waters and one species (H. papillifera) is a new record for Indonesian waters. Two morphospecies (H. aff. macroperona and Stichopus cf. monotuberculatus) need reconfirmation to species level. The highest abundance species of Holothuroidea was found at under rock with 15 species. Whereas, the highest number of individuals was found in seagrass areas with 5457 individuals. H. atra has extensive habitat distribution, such as seagrass, macroalgae, coral reef, dead coral, sand, and under rock. Key words: Baluran National Park, distribution, diversity, Holothuroidea, shallow waters INTRODUCTION Sea cucumbers (Holothuroidea: Echinodermata) are found in various substrates and depths (Sluiter 1901; Samyn et al. 2006; Woo et al. 2013). Approximately, 300 species of sea cucumber were reported in the shallow to deep sea of Indonesian waters (Sluiter 1901; Clark and Rowe 1971; Massin 1996, 1999; Massin and Tomascik 1996; Purwati and Wirawati 2012). Diversity of Holothuroidea in Indonesian waters has been reported, such as Wirawati et al. (2007), Yusron (2006, 2007, 2009a, b, 2010, 2012), Setyastuti (2009), Yusron and Susetiono (2006, 2010), Purwati and Wirawati (2008, 2009, 2011, 2012), Selanno et al. (2014). In marine ecosystem, Holothuroidea help the process of decomposition of organic matter in sediments and produce nutrients in the food chain (Bakus 1973). Some species of Holothuroidea have a high economic value, known as Trepang or Beche-de-Mer. In Asian tropical and sub-tropical waters, Actinopyga, Bohadschia, Holothuria, and Stichopus are exploited as food and medicinal product industry. Whereas, in temperate waters of Japan, Apostichopus japonicus is the most captured by fishery (Conand and Muthiga 2007). Some species of Holothuroidea are listed into Appendix II CITES (Convention on the International Trade in Endangered Species) (Polidoro et al. 2011), because the population of the species declines every year in the world, including in the Indonesian waters (Purwati 2005; Setyastuti and Purwati 2015). Recently, 11 species of sea cucumbers are reported as new records in Johor strait and 10 species are potentially as new species (Woo et al. 2014; Ong and Wong 2015). Kamarudin et al. (2010) also stated that approximately 80 species of sea cucumbers are found in Malaysian waters. The diversity of sea cucumber in Indonesian waters has been studied only in some areas, while exploitations of some species that have economic value occur continuously (Purwati and Wirawati 2009). Expeditions of Holothuroidea in Indonesian waters, including international expeditions, were conducted in the eastern of Indonesia (Sluiter 1901; Massin 1996; Massin 1999). Study of sea cucumber in national parks in Indonesia is still limited. Baluran National Park (BNP) is a conservation area located in the Situbondo district, East Java, Indonesia. Geographically, this park is directly adjacent to two open waters, Bali and Madura straits. BNP is located in the northern coast of Java, which has a variety of substrates and diverse marine habitat, such as sand, mud, rocks, dead coral, seagrass, macroalgae and coral reefs. This paper describes the diversity, distribution, and habitats of each Holothuroidea in shallow waters of BNP. MATERIALS AND METHODS Study sites The study was conducted from July to September 2015 in shallow waters of BNP. Samplings of Holothuroidea were taken in low tide condition in three locations, i.e. Bama, Air Karang, and Bilik (Figure 1). Bama (100,000