Phospholipid-derived fatty acids microbial classes when in fact those PLFAs are present in a broad range of life forms. Phospholipids can occur in many biological classes (such as in plant roots, fungi, as well as in soil bacteria), so care has to be taken in over-assigning PLFA biomarkers to the wrong class. Even though phospholipids occur in many different life forms, the fatty acid side chains between differing life forms can be quite unique. Polyunsaturated fatty acids ("e.g." 18:3 ω3c) are found in plants, algae and cyanobacteria, but are often not present in bacteria. Monounsaturated fatty acids (particularly at the omega-7 position), odd-chain
Algae algae, of which only four are currently considered among algae. In "Systema Naturae", Linnaeus described the genera "Volvox" and "Corallina", and a species of "Acetabularia" (as "Madrepora"), among the animals. In 1768, Samuel Gottlieb Gmelin (1744–1774) published the "Historia Fucorum", the first work dedicated to marine algae and the first book on marine biology to use the then new binomial nomenclature of Linnaeus. It included elaborate illustrations of seaweed and marine algae on folded leaves. W.H.Harvey (1811—1866) and Lamouroux (1813) were the first to divide macroscopic algae into four divisions based on their pigmentation. This is the first use of