Fatty Acid Composition of 35 Species of Marine Invertebrates

Fatty acid compositions of 35 species of marine invertebrates (13 species of Bivalvia, 10 species of Gastropoda, 4 species of Cephalopoda, 4 species of Crustacea, 2 species of Ascidacea, 2 species of Holothuroidea) were studied using gas-liquid chromatography. Total lipids in all samples were very low, ranging from $0.24\%$ to $1.96\%$. The prominent fatty acids were 16:0, 20:5 (n-3), 22:6 (n-3), 18:0, 16:1 (n-7), 20:4 (n-6), 18:1 (n-9) and 18:1 (n-7) in the majority of marine invertebrates. Polyunsaturated fatty acid (PUFA) was the richest fatty acid group in all invertebrates, accounting for $55.3\pm6.70\%$ of total fatty acids (TFA), followed by saturated $(26.2\pm4.33\%)$ and monounsaturated fatty acid $(18.5\pm5.87\% )$. No correlation was found between total lipid content and each fatty acid group. Cephalopoda contained the highest level of n-3 PUFA $(54.6\pm5.17\%)$, while Holothuroidea and Gastropoda contained the lowest level of n-3 PUFA, accounting for $26.5\pm4.44\%$ and $28.4\pm4.04\%$, respectively. Bivalvia and Ascidacea are plankton feeders, which were rich in 20:5 (n-3) and 22:6 (n-3). Carnivorous species of Cephalopoda were prominently rich in 22:6 (n-3), ranging from $26.7\%$ to $46.1\%$ of the TFA. However, some species of Gastropoda are seaweed feeder (herbivorous), which contained high level of 20:4 (n-6) compared to plankton feeder and carnivorous species. In addition, blue and red colored sea cucumbers, and turban shells with and without apophyses belong to the same species, but they live in different habitats. These organisms were found to have different fatty acid compositions. Therefore, fatty acid compositions of these invertebrates might be affected by their different environments, particularly their diet.