The protozoa are an eclectic assemblage of organisms encompassing a wide range of single-celled and multiple-celled colonial organisms lacking tissue organiza tion, but exhibiting remarkably refined biological behavior. In some modern classifications, they are classified as a subkingdom among the Protista (eukary otic single-celled organisms). Although they are not considered a formal cate gory by some taxonomists and some biologists consider the name inappropriate (inferring that they are the first unicellular animals, although some photosynthe size), it is still convenient to consider this group of organisms as an informal collection under the heading of protozoa. Their cosmopolitan distribution, sig nificant ecological role in mineral recycling and enhancement of carbon flow through lower trophic levels of food webs, and remarkable cellular adaptations to enhance survival in diverse environments make them significant organisms for biological investigation. In some cases, biologists are introduced to this group in first level courses or in invertebrate zoology, but never develop a full appreciation for the diverse and biologically sophisticated characteristics of these organisms. This book is intended as a survey of broad concepts in protozoan biology with an emphasis on comparative data. The focus is on the zoological aspects of the group. Topics more closely related to plantlike characteristics, as presented in books on phycol ogy, are not considered in detail here. A sound background in modern biology and an introduction to cellular biology will be helpful in understanding Chapters 15 and 16, which include a substantial amount of information on biochemistry."

The study of marine plankton has traditionally focused on those or ganisms that appeared to have obvious ecological significance in un derstanding the major patterns of biological productivity, trophic relations, community structure, and the dynamic interaction of living things with the physical environment. Not infrequently, this thrust has centered on the apparently most abundant and/or larger members of the plankton community, including significant primary producers such as the diatoms, nonthecate algae, and flagellates, or the major con sumers--copepods, gelatinous metazoa, and other abundant metazoan invertebrates. Consequently, some of the less well recognized but also abundant microzooplankton have been given less attention. The radio laria, although widely studied as fossils by micropaleontologists, have in modem times. This is la been relatively neglected by biologists mentable given their widespread distribution in the oceans, remarkably complex form, and not infrequently localized abundance. Their diver sity of form, encompassing solitary species of microscopic dimensions and colonial species as large as several centimeters or more, challenges us to explain their evolutionary origins, explore their structural-func tional correlates, and comprehend the ecological basis for their wide spread occurrence in all oceans of the world fromihe greatest depth to the surface of the sea. Their intricate and aesthetically pleasing skeletons of enormous variety and fine-detailed design formed from amorphous silica (opaline glass) offer a unique biomineralized product that defies immediate biological explanation."