Unusual fatty acid composition of storage lipids in the bresilioid shrimp Rimicaris exoculata couples the photic zone with MAR hydrothermal vent sites

Lipid and stable carbon isotope analyses of Rimicaris exoculata, the domina nt bresilioid shrimp found at the MAR (Mid-Atlantic Ridge) vent sites, have indicated that these animals possess a highly unusual storage lipid compos ition. The dominant neutral Lipid classes, triacylglycerols and wax esters, contained very high levels of polyunsaturated fatty acids (PUFA, up to 89% of neutral lipid fatty acids). Gas chromatography isotope ratio mass spect rometry (GC-IRMS) analysis of the PUFA from neutral lipid gave delta(13)C ( v-PDB) values of -17.6 to -27.1 parts per thousand, which is within the ran ge expected for a photosynthetic origin for these compounds. Fatty acid ana lyses of bacterial/detrital material collected from the vent sites containe d only very low amounts of PUFA. It is clear from these findings that R. ex oculata has evolved a highly specialized lipid metabolism which allows it t o store substantial amounts of PUFA during its early planktotrophic life st ages. These PUFA reserves will be subsequently mobilized to enable growth a nd maturation of the shrimp on return to a suitable vent site and are there fore an important factor allowing R. exoculata to inhabit deep sea vent eco systems.