Similarities between the biochemical composition of jellyfish body and mucus

Abstract

Recognition of the importance of jellyfish in marine ecosystems is growing. Yet, the biochemical composition of the mucus that jellyfish constantly excrete is poorly characterized. Here we analyzed the macromolecular (proteins, lipids and carbohydrates) and elemental (carbon and nitrogen) composition of the body and mucus of five scyphozoan jellyfish species (Aurelia aurita, Chrysaora fulgida, Chrysaora pacifica, Eupilema inexpectata and Rhizostoma pulmo). We found that the relative contribution of the different macromolecules and elements in the jellyfish body and mucus was similar across all species, with protein being the major component in all samples (81 ± 4% of macromolecules; 3.6 ± 3.1% of dry weight, DW) followed by lipids (13 ± 4% of macromolecules; 0.5 ± 0.4%DW) and carbohydrates (6 ± 3% of macromolecules; 0.3 ± 0.4%DW). The energy content of the jellyfish matter ranged from 0.2 to 3.1 KJ g^-1 DW. Carbon and nitrogen content was 3.7 ± 3.0 and 1.0 ± 0.8%DW, respectively. The average ratios of protein:lipid:carbohydrate and carbon:nitrogen for all samples were 14.6:2.3:1 and 3.8:1, respectively. Our study highlights the biochemical similarity between the jellyfish body and mucus and provides convenient and valuable ratios to support the integration of jellyfish into trophic and biogeochemical models.

Keywords: carbohydrate; carbon; lipid; nitrogen; protein.

Fig. 1

Comparison of the macromolecular content (protein, lipid, carbohydrate; A, B and C) and the sum of macromolecules to the ash-free dry weigh (AFDW, D) of mucus and body tissues in jellyfish species (A. aurita, C. fulgida, C. pacifica, E. inexplicata and R. pulmo) expressed as percentage of dry wet (%DW) of the samples. The lines represent the linear regressions and the shaded area is the confidence interval (see details in SI, Supplementary Table S2). The solid lines are the linear regressions on the whole data set with (A) lipid (LD) vs protein (PT; LD = 0.10 ± 0.01 PT + 0.10 ± 0.03), (B) carbohydrate (CH) vs lipid (CH = 0.78 ± 0.10 LP—0.05 ± 0.06), (C) carbohydrate vs protein, (CH = 0.10 ± 0.01 PT—0.04 ± 0.05) and (D) sum of macromolecules (SM) vs AFDW (SM = 1.12 ± 0.03 AFDW +11.24 ± 0.16).

Fig. 2

Proportion of proteins, lipids and carbohydrates (A) and carbon and nitrogen (B) in the body and mucus of jellyfish species (A. aurita, C. fulgida, C. pacifica, E. inexplicata and R. pulmo) expressed as percentage of the dry weight (DW) of the sample and as relative proportion of the total proteins, lipids and carbohydrates (C) and carbon and nitrogen (D) content. The dots represent the C:N ratio (D).

Fig. 3

Energy content of the body (dark gray) and mucus (light gray) of jellyfish species (A. aurita, C. fulgida, C. pacifica, E. inexplicata and R. pulmo) normalized to the dry weight (DW) of the samples (A). Error bars show the standard deviation. Linear regression between the energy content (EC) and the carbon content (CC) of jellyfish body (circles) and mucus (triangles; B). The lines represent the linear regressions and the shaded area is the confidence interval (see details in SI, Supplementary Table S2). The solid line is the linear regressions on the whole data set (EC = 35.03 ± 1.27 CC—0.05 ± 0.06, SI, Supplementary Table S2).