- Introduction

Microalgae are single-celled, ubiquitous, prokaryotic and eukaryotic primary photosynthetic microorganisms that are taxonomically and phylogenetically diverse. The advanced plant life of today is thought to have evolved from these simple microscopic plant-like entities. In general, the algae are a heterogeneous group of polyphyletic photosynthetic organisms with an estimated 350,000 known species (Brodie and Zuccarella, 2007). There are predominantly two prokaryotic divisions (Cyanophyta and Prochlorophyta) and nine eukaryotic divisions (Glaucophyta, Rhodophyta, Heterokontophyta, Haptophyta, Cryptophyta, Dinophyta, Euglenophyta, Chlorarachniophyta, and Chlorophyta). The biology of microalgae is interesting, and their enigma is due to their wide diversity as well as their plethora of habitats. The biology of microalgae is discussed extensively in Chapter 2 of this book.