Spongivore ecology in the Turkish seas: Notes on the first in-situ record of Umbraculum umbraculum ([Lightfoot], 1786) on Demosponge Calyx nicaeensis (Risso, 1826) populations from the mesophotic depths of Bozcaada (Aegean Sea, Türkiye)

H. Barış Özalp, Alper Evcen

ORCID IDs: H.B.Ö: 0000-0003-2640-8912, A.E.: 0000-0003-1134-2551

Underwater Technology Section, Maritime Vocational School, Çanakkale Onsekiz Mart University, 17100, TÜRKİYE
Water Quality Lab, Faculty of Marine Science and Technology, Çanakkale Onsekiz Mart University, 17100, TÜRKİYE
TÜBİTAK Marmara Research Center, TÜBİTAK, Gebze/Kocaeli, 41470, TÜRKİYE

Abstract

The diversity and ecological importance of sea slugs (Heterobranchia) in the Turkish seas are largely unknown. This is particularly true for spongivorous invertebrates, whose roles in these ecosystems remain uninvestigated. These taxa, although often overlooked, play important roles in shaping benthic communities through selective predation on sponge species. The aim of this study is to contribute to the knowledge of spongivore ecology in the eastern Mediterranean by documenting the first in-situ observations of the rare heterobranch Umbraculum umbraculum feeding on the demosponges Calyx nicaeensis and Suberites domuncula at mesophotic depths around Bozcaada Island (Aegean Sea, Türkiye) and the Çanakkale Strait. This finding reveals a highly specialized predator-prey interaction and extends the known distribution of U. umbraculum in the region. By providing novel ecological data from an understudied depth zone and taxonomic group, this study underscores the importance of incorporating spongivorous species into broader benthic biodiversity assessments.

Keywords: Spongivory, sponge, Çanakkale Strait, Bozcaada, Gökçeada, Aegean Sea

Pages: 130-141

References

Albano, P.G., Azzarone, M., Amati, B., Bogi, C., Sabelli, B., Rilov, G. (2020) Low diversity or poorly explored? Mesophotic molluscs highlight undersampling in the Eastern Mediterranean. Biodiversity Conservation 29: 4059-4072.

Allmon, R.A., Sebens, K.P. (1988) Feeding biology and ecological impact of an introduced nudibranch, Tritonia plebeia, New England, USA. Marine Biology 99: 375-385.

Arias, A., Crocetta, F. (2016) Umbraculum umbraculum (Gastropoda: Heterobranchia) spreading northwards: additional evidence to the “tropicalization” of the Bay of Biscay. Cahiers de Biologie Marine 57: 285-286.

Ballesteros, M., Madrenas, E., Pontes, M. (2025b) Umbraculum umbraculum in OPK-Opistobranquis. Available at: https://opistobranquis.info/en/guia/umbraculida/umbraculum–umbraculum/ (accessed 11 Jul 2025).

Ballesteros, M., Madrenas, E., Pontes, M. (2025a) Felimare tricolor in OPK-Opistobranquis. Available at: https://opistobranquis.info/en/guia/nudibranchia/doridina/doridoidei/doridoidea/felimare-tricolor/ (accessed 18 May 2025).

Ballesteros, M., Valdés, A. (1999) Redescripción de Baptodoris cinnabarina Bergh, 1884 (Opisthobranchia, Doridina, Platydorididae) y discusión taxonómica de otras especies del género Baptodoris Bergh. Iberus 17: 27-35.

Belmonte, T., Alvim, J., Padula, V., Muricy, G. (2015) Spongivory by nudibranchs on the coast of Rio de Janeiro state, southeastern Brazil (Mollusca, Gastropoda). Spixiana 38(2): 187-195.

Bertsch, H., Valdés, Á., Gosliner, T.M. (2009) A new species of tritoniid nudibranch, the first found feeding on a zoanthid anthozoan, with apreliminary phylogeny of the Tritoniidae. Proceedings of the California Academy of Sciences 60(10): 431.

Bouchet, P. (1977) Opisthobranches de profondeur de l’Océan Atlantique: II-Notaspidea et Nudibranchiata. Journal of Molluscan Studies 43(1): 28-66.

Caballer, M., Rosenberg, G., Gofas, S. (2015) Umbraculum umbraculum MolluscaBase. Available at: https://www.molluscabase.org/aphia.php?p=taxdetails&id=141879 (accessed 7 Jun 2025).

Calado, R., Leal, M.C. (2015) Trophic ecology of benthic marine invertebrates with bi-phasic life cycles: what are we still missing? Advances in Marine Biology 71: 1-70.

Cattaneo-Vietti, R. (1991) Nudibranch molluscs from the Ross Sea, Antarctica. Journal of Molluscan Studies 57(Supplement Part 4): 223-228.

Cerrano, C., Molinari, A., Bernat, P., Baldacconi, B., Calcinai, B., Macic, V. (2013) Calyx nicaeensis (Risso, 1826) (Porifera, Demospongiae). Is it a rare and threatened species? Rapports de la Commission international pour la Mer Méditerranée 40: 771.

CIBSUB (2025) Felimare tricolor. Available at: https://www.cibsub.cat/ bioespecie_es-felimare_tricolor-28154 (accessed 27 Jun 2025).

Cirivasi, F. (2024) Umbraculum umbraculum in intotheblue.it. Available at: https://www.intotheblue.it/en_GB/2024/03/13/umbraculum-mediterraneum/ (accessed 7 Jul 2025).

Cronin, G., Hay, M.E., Fenical, W., Lindquist, N. (1995) Distribution, density, and sequestration of host chemical defenses by the specialist nudibranch Tritonia hamnerorum found at high densities on the sea fan Gorgonia ventalina. Marine Ecology Progress Series 119: 177-189.

Furfaro, G., Fumarola, L.M., Toso, A., Toso, Y., Trainito, E., Bariche, M., Piraino, S. (2025) A Mediterranean melting pot: native and non-indigenous sea slugs (Gastropoda, Heterobranchia) from Lebanese waters. BioInvasions Records 14(1): 197-221.

Gönülal, O., Dalyan, C. (2017) Deep-sea biodiversity in the Aegean Sea. In: Mediterranean Identities – Environment, Society, Culture. IntechOpen, Bjelovar, pp. 149-178.

Lombardo, A., Marletta, G. (2022) New observations on two umbraculid molluscs: Tylodina perversa (Umbraculida: Tylodinidae) and Umbraculum umbraculum (Umbraculida, Umbraculidae) along the central eastern coast of Sicily. Travaux du Muséum National d’Histoire Naturelle “Grigore Antipa” 65(2): 15-25.

Mullins, D. A. (2021) Spongivores – The sponge eaters. Available at: https://nudibranchdomain.org/spongivores-the-sponge-eaters/ (accessed 11 Jul 2025)

Özalp, H. B. (2019) Denizler Altında Yapay Habitatlar: Bozcaada Resiflerine ve Biyoçeşitliliğe Bir Bakış. Özen Publishing, Canakkale, Turkey.

Özalp, H. B. (2023). Özalp, H. B. (2023). Dardanos Coral Reef in the Çanakkale Strait: Biodiversity and Underwater Marine Life. Turkish Marine Research Foundation, Istanbul, Türkiye..

Özalp, H. B. (2025) Türk Boğazlar Sistemi: Denizel Yaşam ve Biyoçeşitlilik. Gece Kitaplığı Publishing, Ankara, Türkiye.

Özalp, H. B., Demir, V., Evcen, A., Önen-Tarantini, S., Montesanto, F., Erdoğan, S., Çulha, M., Kocak, F. (2022) Pre-assessment of zoobenthos diversity from the only hard coral Marine Reserve in the Turkish Seas (Çanakkale Strait, Türkiye). Regional Studies in Marine Science 55: 102571.

Pontes, M. (2018) Cómo distinguir los «felimare» azules,” en VIMAR-Vida Marina Available at: https://vidamarina.info/?p=156#:~:text=Los%20rin%C3% B3foros%20son%20azules%20con%20una%20l%C3%ADnea%20longitudinal%20amarilla%20en,interna%20de%20cada%20hoja%20branquial (accessed 27 Jun 2025).

Rizgalla, J., Krug, P.J. Christa, G. (2025) Nudibranchs from Libyan Waters. Thalassas 41: 138.

Smith, V.G., Gosliner, T.M. (2003) A new species of Tritonia from Okinawa (Mollusca: Nudibranchia), and its association with a Gorgonian octocoral. Proceedings-California Academy of Sciences 54(16): 255-278.

Toma, M., Betti, F., Bavestrello, G., Cattaneo-Vietti, R., Canese, S., Cau, A., Bo, M. (2022) Diversity and abundance of heterobranchs (Mollusca, Gastropoda) from the mesophotic and bathyal zone of the Mediterranean Sea. The European Zoological Journal 89(1):167-189.

Trainito, E., Fantin, M., Manganelli, E., Furfaro, G. (2021) What are you doing here? Investigating on an unexpected association in shallow Mediterranean dark caves sheds light on the diet of Marionia blainvillea (Mollusca, Gastropoda, Nudibranchia). Turkish Journal of Zoology 45(7): 550-556.

Valdés, A., Gosliner, T. M. (2001) Systematics and phylogeny of the caryophyllidia-bearing dorids (Mollusca, Nudibranchia), with descriptions of a new genus and four new species from Indo-Pacific deep waters. Zoological Journal of the Linnean Society 133(2): 103–198.

Valdés, A., Lundsten, L., Wilson, N.G. (2018) Five new deep-sea species of nudibranchs (Gastropoda: Heterobranchia: Cladobranchia) from the Northeast Pacific. Zootaxa 4526(4): 401-433.

Wägele, H., Klussmann-Kolb, A. (2005) Opisthobranchia (Mollusca, Gastropoda) – more than just slimy slugs. Shell reduction and its implications on defence and foraging. Frontiers in Zoology 2: 1-18.

Willan, R.C. (1984) A review of diets in the Notaspidea (Mollusca: Opisthobranchia). Journal of the Malacological Society of Australia 6: 125-142.

Willan, R.C. (1998) Order Notaspidea. In: Mollusca: The Southern Synthesis. Fauna of Australia (eds., Beesley, P.L., Ross, G.J.B., Wells, A.) Vol. 5 Part B. CSIRO Publishing, Melbourne, pp. 977-980.