Journal of Threatened Taxa | | 26 October 2022 | 14(10): 21961–21967



ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print)

#7495 | Received 03 June 2021 | Final received 06 October 2022 | Finally accepted 13 October 2022




First report of marine sponge Chelonaplysilla delicata (Demospongiae: Darwinellidae) from the Andaman Sea/Indian Ocean with baseline information of epifauna on a mesophotic shipwreck


Rocktim Ramen Das 1, Titus Immanuel 2 , Raj Kiran Lakra 3, Karan Baath 4 & Ganesh Thiruchitrambalam 5


1,2,3,5 Department of Ocean Studies and Marine Biology, Pondicherry University, Port Blair Campus, Andaman Islands, Andaman & Nicobar 744101, India.

1 Graduate School of Engineering and Science, University of the Ryukyus, Nishihara 903-0213, Okinawa, Japan.

2 Marine Biology Regional Center (MBRC), Zoological Survey of India (ZSI), Chennai, Tamil Nadu 600005, India.

4 Infinity Scuba Andaman’s, Chidiyatapu, Port Blair, Andaman Islands, Andaman & Nicobar 744101, India.

1 (corresponding author), 2, 3,

4, 5



Abstract: During a biodiversity assessment on a wreck located in the Andaman Sea (Andaman Islands), a single specimen of sponge Chelonaplysilla delicata was recorded. Our finding confirms the species taxonomy and highlights the current observation as a first report from the Andaman Sea/Indian Ocean. The baseline information on epifaunaof the wreck is further stated in this study.


Keywords: Biodiversity, epifauna, invasive, Porifera taxonomy, Tubastraea.




Editor: R. Ravinesh, Gujarat Institute of Desert Ecology, Kachchh, India.         Date of publication: 26 October 2022 (online & print)


Citation: Das, R.R., T. Immanuel, R.K. Lakra, K. Baath & G. Thiruchitrambalam (2022). First report of marine sponge Chelonaplysilla delicata (Demospongiae: Darwinellidae) from the Andaman Sea/Indian Ocean with baseline information of epifauna on a mesophotic shipwreck. Journal of Threatened Taxa 14(10): 21961–21967.


Copyright: © Das et al. 2022. Creative Commons Attribution 4.0 International License.  JoTT allows unrestricted use, reproduction, and distribution of this article in any medium by providing adequate credit to the author(s) and the source of publication.


Funding: Self-funded.


Competing interests: A preprint of this manuscript was uploaded on Bioarxiv preprint server on 15 May 2019. The preprint can be accessed at


Author details: Rocktim Ramen Das finished his master’s in marine biology from Pondicherry University, Port Blair Campus, where he was exploring the epifaunal diversity in old shipwrecks. He then was associated with the National Centre for Sustainable Coastal Management, Govt. of India. He later acquired the embassy recommended MEXT scholarship from the Japanese government and is currently a PhD student working with Prof. James Reimer at the Molecular, Invertebrates, Systematics and Ecology (MISE) Laboratory, University of the Ryukyus, Okinawa, Japan. He is entrusted with understanding coral diseases and health within the Ryukyu archipelago of Japan. Until now, he has authored and co-authored seventeen research articles with two book chapters in the fields of coral diseases, coral reproduction, coral ecology, artificial reefs, and marine sponges etc.

Dr. Titus Immanuel is currently working as a post-doctoral researcher at the Centre for Ecological Sciences, Indian Institute for Science (CES, IISc) on multiple projects. His main research interests lie in understanding Poriferan taxonomy, marine invertebrate biodiversity documentation, coral health and reef resilience studies. 

Dr. Raj Kiran Lakra is a marine biologist with expertise in benthic communities. He has a master’s degree and a PhD from Pondicherry University. He has worked on various benthic fauna and on seagrass ecosystem. His main interest lies in the taxonomy and ecology aspect of marine annelids (Polychaeta).  He is interested in understanding the functional response of Macrobenthic communities to the existing environmental conditions.

Karan Baath is a dive instructor/owner at the Infinity Scuba Dive School located in Chidiyatapu, Andaman Islands. He is one of the pioneers who have explored majority of the islands within the Andaman and Nicobar Archipelago.

Dr. Ganesh Thiruchitrambalam is working as an assistant professor in the Department of Ocean Studies and Marine Biology at Pondicherry University, Port Blair Campus. He has published several papers in the fields of marine benthic ecology, coastal ecological quality status assessment, seagrass ecosystems, intertidal ecology, marine molluscs, polychaete taxonomy and ecology, and Brachyuran crabs of the Andaman Islands. Dr. Ganesh is teaching courses on Marine Invertebrates, Marine Vertebrates, and Marine Environmental Impact Assessment for MSc students. He has published book chapters with National and International publishers. He has participated in several scientific cruises in the Bay of Bengal, the Arabian Sea, and the Indian Ocean. He has also been a part of the Indian research team in the exploration of the Arctic Ocean.


Author contributions: RRD—conceptualization, study design, writing original draft, reviewing & editing, field assessment, sample collection, data analysis, laboratory analysis. TI—writing original draft, reviewing & editing, sample identification, laboratory analysis. RKL—study design, writing, reviewing & editing, field assessment. KB—field assessment. GT—study design, writing, reviewing & editing, supervision.


Acknowledgements:  The authors thank Dr. P.M. Mohan, former head of the Department of Ocean studies and Marine Biology (DOSMB), Andaman Campus, Pondicherry Central University (PU) for the necessary facilities. Dr. S. Venu (DOSMB, PU), for suggestions and recommendations during the initial phase of the study. Dr. F. Sinniger (University of the Ryukyus, Japan) for comments on mesophotic ecosystem. Drs. K. Wangkulangkul (Prince of Songkla University, Thailand), and S.Y. Tenjing (National Centre for Sustainable Coastal Management, India) for comments on English language.  The authors are grateful to Dr. Sourabh Kumar Dubey (Susama Devichowdhurani Marine Biological Research Institute, Sundarbans, India) for preparing the Bengali abstract and acknowledges the assistance in APC transaction by Ms. Moramee Das.





The Andaman Sea, an eastern subdivision of the Indian Ocean, is bordered by countries like Thailand and Myanmar on the east and the Andaman archipelago (Andaman & Nicobar Islands/ANI) on the west (Figure 1) (Brown 2007). A large portion, however, falls within the boundary of the Coral Triangle Initiative (CTI) (Rudi et al. 2012). Studies related to its marine biodiversity or the coral reef ecosystem have been comparatively understudied or scattered (Aungtonya et al. 2000; Brown 2007). Additionally, the Andaman Sea possesses several shipwrecks (Kheawwongjan & Kim 2012) acting as artificial reef ecosystems, knowledge pertaining to which is mostly limited in the region. These sunken structures provide space for the growth and establishment of various sessile marine communities like poriferans (Walker et al. 2007; Lira et al. 2010) and other non-native species (Patro et al. 2015; Soares et al. 2020). Within the Indian Exclusive Economic Zone (EEZ), recent studies targeting shallow-water wrecks have filled important knowledge gaps (example Mohan 2013; Das 2014; Yogesh-Kumar et al. 2015) (Table 1). This article further adds essential information about these rarely studied ecosystems at a mesophotic depth and reports a marine sponge from the Andaman Sea/Indian Ocean.





The sponge, Chelonaplysilla delicata (Image 1), was collected from the shipwreck HMIS SM* during a survey conducted to document epifaunal diversity from February to March 2014. The wreck is a 70-m long Royal Indian navy minesweeper that sank in the year of 1942. It is located at a depth of 33m near Chidiyatapu on the edge of the Macpherson Strait (11.477°N, 92.703°E) (Figure 1). Water transparency and temperature were recorded with a Secchi disc and a dive calculator. After collection, the specimen was preserved in 100% ethanol. A surface peel of the easily separable cortex of the specimen was removed and placed in xylene for 24 hours, after which a permanent slide of the peel was mounted with DPX. A single fibre with its base and branches intact was removed from the sponge for species-level identification under a stereo microscope (Image 1B–D). The specimen was identified following Pulitzer-Finali & Pronzato (1999). The preserved specimen is deposited in the National Zoological Collections (NZC) of the Andaman & Nicobar Regional Centre (ANRC), Zoological Survey of India (ZSI), Port Blair.

Benthic cover was assessed by randomly placing 20 (0.25 x 0.25 m) quadrats (Image 2). The photographs were analysed using open-sourced Coral-Net software (Beijbom et al. 2012), and the epifauna was classified into Unknown, Porifera, Scleractinian, Ircinia sp. (Porifera), Algae, Iotrochota sp. (Porifera), Sediment, Tubastraea aff. coccinea, Tubastraea micranthus, Hard Substrate, Ascidian, and Bleached Coral (modified from Zintzen et al. 2006). Other specimens not within the quadrat have been identified wherever possible to the lowest possible taxonomic level. Later, the data from the annotated quadrats was transferred and processed in Microsoft Excel® (Microsoft 365 MSO, 16.0.13001.20266/32bit). Study maps were created using the open-sourced Quantum Geographic Information System (QGIS ver. 3.6).






Phylum: Porifera

Class: Demospongiae

Order: Dendroceratida

Family: Darwinellidae

Genus: Chelonaplysilla

Species: Chelonaplysilla delicata Pulitzer-Finali & Pronzato, 1999

Paratype: ZSI/ANRC – 14321, 2014, 1 ex., India: Andaman Island: South Andaman: Chidiyatapu (11.477 °N, 92.703 °E), coll. Rocktim Ramen Das.



Chelonaplysilla delicata predominantly thickly encrusting (<10 mm) but has erect lobes that are about 4----–-5 cm high. The sponge surface is conulose, and the acute conules separated from each other by 2–5 mm. Oscules 1–3 mm in diameter, flush with the surface and unevenly distributed all over on sponge surface. The texture is soft collapsible and feeble. The fresh specimen was dark violet or purple in colour and retained its colour even in the preserved condition. Sponge surface covered by structured regular reticulation of sand and spicule detritus, which forms regular roundish or oval meshes of 90–155 µm. This reticulation is typical of the genus. Regular rounded fibrous pores, inhalant in nature, is enclosed within these rounded meshes (Image 1D). The skeleton is dendritic, made up of pigmented fibres fragile in nature with repeated branching that originate from a basal spongin plate (Image 1 B,C) and extends towards the boundary. The primary fibre measured to be around 0.4 mm at its thickest. Spicules are absent.



India: Andaman Sea (ANI, South Andaman, Present study). Elsewhere: Bismarck Sea (Papua New Guinea) (Pulitzer-Finali & Pronzato 1999), Indonesia (Sulawesi) (GBIF 2000), Palau (Micronesia) (Ridley et al. 2005), French Polynesia (Alencar et al. 2017) (Figure 2).



Chelonaplysilla delicata is very similar to C. erecta (Tsurnamal, 1967); however, the latter has fibres anastomosing in nature, whereas the thickness of fibres in C. delicata fades in diameter. The specimen mentioned in Pulitzer-Finali & Pronzato (1999) is gray, whereas our specimen is dark maroon in live condition (Image 1A). The specimen was initially misidentified as C. erecta (Das 2014; Das et al. 2016). Thus, there was a need for an update and filling of knowledge gaps in this species distribution range.



The family Darwinellidae possesses sponging fibres with a proper skeleton and fibrous spicules (Van Soest 1978; Bergquist & Cook 2002). It consists of five recognised genera and 45 accepted species. Chelonaplysilla is the only genus which is devoid of spicules but consists of a fibrous dendritic skeleton that possesses a distinct laminated bark surrounding a central pith region. A structured and separable cortex that is reinforced by a delicate reticulation of sand grains (Van Soest 1978) distinguishes this genus.


Wreck Biodiversity

Benthic cover assessment (Image 2) reveals that Poriferans were the second most abundant group on the surface of the wreck, mostly encrusting in nature. In most instances, the encrusting sponge genus Iotrochota was readily visible. Ahermatypic and invasive sun corals were abundant in selected localities and may have found a successful substrate for further expansion (Image 2A, 3). Few polyps of Tubastraea micranthus had signs of bleaching, a stark contrast to their ahermatypic nature. Updated and revised identification following Das et al. (2016) on the wreck surface includes scleractinian genera Favia, Symphyllia, Podabacia crustacea, and Leptoseris. A single individual of the Gastropod genus (Chicoreus) and a few crinoids. The identified poriferan families include Irciniidae (Ircinia), Chalinidae (Haliclona (Reniera)); Thorectidae (Hyrtios), Iotrochotidae (Iotrochota baculifera), Thorectidae (Dactylospongia), and Dysideidae (Dysidea sp.). Tunicates comprised Didemnidae (Didemnum), Perophoridae (Perophora), and other unidentified spp.

The faunal organisms that thrive in artificial reefs (shipwrecks) are an important part of the marine community (Zintzen et al. 2006; Amaral et al. 2010). With increasing anthropogenic impacts on natural coral reef habitats, artificial reefs are regarded as a successful alternative (Perkol-Finkel & Benayahu 2005). As a result, it becomes important to understand the biological communities growing in these habitats (Thanner et al. 2006). Sponges, which naturally occupy shipwrecks, are one of the dominant organisms in such habitats, as evidenced in the present study. However, its diversity will be strictly limited to the environmental settings. For example, some species of the genus Iotrochota are found in sheltered environments (Cleary & de Voogd 2007) as seen in our observation (Image 2C). Similarly, shipwrecks are also known to act as successful substrates for many non-native species, as reported from the Atlantic and the Red Sea (Perkol-Finkel et al. 2006; Soares et al. 2020). Repeated encounter of Tubastraea aff. coccinea (Image 2A) earlier misidentified as Dendrophyllia sp. and T. micranthus (Image 3) in the study site is a strong evidence from the Andaman Sea (Das et al. 2016) (Figure 1). The sponge species reported herein is at a much-extended depth compared to its initial described type locality (see Pulitzer-Finali & Pronzato 1999).

Technical difficulties have hampered studies on these habitats at mesophotic depths (Massin et al. 2002; Zintzen et al. 2006). But with the rapid scale development of remotely operated vehicles and submersibles, detailed exploration of these ecosystems can be well predicted. Further, these areas might be a hub for various underexplored flora and fauna and might be effective in reviving threatened marine life due to the loss of natural ecosystems.


For figures & images – click here for full PDF





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