Insights gained from the chemical composition of spicules in Haplosclerida (Porifera, Demospongiae)

ABSTRACT

The shape and arrangement of skeletal structures (spicules) in marine sponges are used in their taxonomic classification but shared spicule patterns often do not correspond to relationships postulated by molecular data, particularly for members of the order Haplosclerida. A chemical and spectroscopic analysis of spicules using FTIR-ATR (Fourier transform infrared spectroscopy), ICP-OES (inductively coupled plasma-optical emission spectrometry) and ICP-MS (inductively coupled plasma-mass spectrometry) was undertaken for nine Haliclona species from Irish and Mediterranean coasts to determine whether the chemical composition of the spicules could reflect a phylogenetic signal. The analysis indicates differences in the amounts of major and minor elements present in spicules across the nine species but differences do not reflect phylogenetic relationships. H. indistincta (a shallow sublittoral species) harbours much higher amounts of some elements in the spicules than the remaining (subtidal) species with H. viscosa showing much higher levels of zinc.

SUBJECT EDITOR:

• Paco Cárdenas

KEYWORDS:

• Sponges
• spicules
• silica
• Haliclona species
• chemical composition
• FTIR spectroscopy

Acknowledgements

The authors acknowledge the facilities and scientific and technical assistance of the NCBES Electron Microscopy unit within the Centre for Microscopy and Imaging at the National University of Ireland Galway, a facility that is funded by NUIG and the Irish Government’s Programme for Research in Third Level Institutions, Cycles 4 and 5, National Development Plan 2007-2013. Eadaoin Timmins helped in the process of generating images from the FTIR-ATR. Olivier P. Thomas helped with the collection and identification of the sponges from the Mediterranean. Bernard Picton, Christine Morrow and Eoin MacLoughlin helped with the collection and identification of sponges from Irish waters.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Grace P. McCormack http://orcid.org/0000-0003-4960-5185

Additional information

Funding

This work was supported by Hardiman Scholarship, NUIG (awarded to JMAC).