The Harbor Seal Phoca vitulina concolor De Kay: Comparative Details of Fatty Acids in Lung and Heart Phospholipids and Triglycerides

The fatty acids of phospholipids and of triglycerides from the lungs and heart of the harbor seal Phoca vitulina concolor De Kay show distinctive differences from the depot (blubber) fat. Primarily, this is due to greatly elevated levels of 20:4ω6 in the phospholipids. Although these have about the same total C20 and C22 polyethylenic acids with five and six double bonds as the depot fat, they occur in different proportions emphasizing 20:5ω3 rather than 22:6ω3. The organ triglycerides resemble the phospholipids in saturated fatty acid composition and the depot fats in monoethylenic fatty acid composition, but have remarkably low levels of 20:5ω3, 22:5ω3, and 22:6ω3 compared to the depot fat. Comparisons are made with phospholipids from the lungs of the leatherback turtle Dermochelys coriacea coriacea Linnaeus but the novel trans-6-hexadecenoic acid found in the turtle lipids could not be detected in the seal lipids.