Temperature‐ and size‐associated differences in the skeletal structures and osculum cross‐sectional area influence the pumping rate of contractile sponge Cinachyrella cf. cavernosa

Abstract

Sponges alter the proportion of structural and morphological components such as spicule skeleton and number of oscula in response to environment, development and growth. Such mechanisms indicate morphological and physiological variations within populations. We measured the pumping rate of different sized specimens of contractile sponge Cinachyrella cf. cavernosa present in the intertidal rock pools, during morning and afternoon low tides along the central west coast of India. Additionally, we measured the exhalant opening (oscular cross‐sectional area—OSA), tissue density, spicule skeleton weight and the abundance of choanocyte chambers to assess the morphological variations. Water temperature and sponge size showed a significant positive effect on pumping rate. OSA and the number of oscula increased with sponge size, but the sponge volume‐specific pumping rate did not increase (0.029 ± 0.020 ml/s ml‐1). Histological sections showed the abundance of chaonocyte chambers increased marginally with the sponge size, but the contraction state affected the count. Both tissue density and spicule skeleton weight were positively correlated with sponge size, particularly the increase in the size and number of spicule bundles radiating from the centre indicated a denser core in larger specimens. The subcortical lacunae and the peripheral choanosome with high abundance of canals appear to be the major volume reduction zones during contraction events. Our results indicate that the size and number of spicule bundles increase with sponge volume and the variation in temperature, contraction state, and size and number of oscula influence the pumping rate of C. cf. cavernosa.

In situ Pumping Rate of 20 Marine Demosponges Is a Function of Osculum Area

“…This hypothesis is supported by observations in Cinachyrella cf. cavernosa where the number of choanocyte chambers increased only marginally with the increase in sponge volume (Dahihande and Thakur, 2019).…”

“…This decrease may be associated with an increase of the density of structural elements (e.g., spicules) that is required to stabilize and strengthen the larger and often higher structure and also to the need for larger canals. Structural differences were observed between different species (Turon et al, 1997) and empirical data showed that differences in the amount of spicules may vary with sponge volume (Barthel and Theede, 1986;Bavestrello et al, 2000;Dahihande and Thakur, 2019). Further studies are needed to explore the variation of structural and functional units over sponge size and age in relation to sponge pumping.…”

“…As the sponge increases in size, the number and size of the aquiferous modules increase (Wiens et al, 2006). Consequently, their aquiferous system may become more complex (Gaino et al, 1995;Hammel et al, 2012) as reflected by the increase of number of oscula and their cross-sectional area in larger specimens (Gili et al, 1984;Dahihande and Thakur, 2019). Quantitative description of the aquiferous module and the relationships between the aquiferous module and sponge size are yet to be provided.…”

“…Quantitative description of the aquiferous module and the relationships between the aquiferous module and sponge size are yet to be provided. Only few studies have explored the allometric scaling of the increase in the number of oscula and the osculum cross-sectional area and its consequences for sponge pumping (Dahihande and Thakur, 2019;Goldstein et al, 2019;Kealy et al, 2019).…”

“…Environmental factors such as temperature, food concentration, suspended sediment concentration, water flow, and viscosity have been observed to affect sponge pumping rates in laboratory and in situ experiments (Reiswig, 1971;Vogel, 1974;Frost, 1980;Riisgård et al, 1993;Riisgård and Larsen, 1995;Tompkins-MacDonald and Leys, 2008;Grant et al, 2018Grant et al, , 2019Dahihande and Thakur, 2019). Intrinsic factors, such as osculum cross-sectional area, microbial abundance, choanocyte density, reproductive stage, and sponge volume have also been shown to affect sponge pumping rates (Weisz et al, 2008;Massaro et al, 2012;McMurray et al, 2014;Strehlow et al, 2016;Dahihande and Thakur, 2019;Goldstein et al, 2019;Morganti et al, 2019). Pumping rate has been observed to increase with sponge volume in several studies (Thomassen and Riisgård, 1995;Kowalke, 2000;McMurray et al, 2014;Lewis and Finelli, 2015;Morganti et al, 2019), indeed the latter has been shown to be the major determinant of pumping rate.…”