his book focuses on tropical photoautotrophs in several groups:the "green algae"chlorophyta;"red algae"rhodophyta;"brown algae"phaeophyta;"blue-green algae"cyanophyta;diatoms chrysophyta;and dinoflagellates pyrrhophyta.this chapter provides an overview of what algae are,how they reproduce,their physical and chemical requirements,and special features of their structure and biology.i offer more detailed information about the distinguishing features of these different algae groups in chapter three.