Protozoology is the study of protozoa, which are "animal-like" protists. The term is obsolete due to a better understanding of the evolutionary relationships of eukaryotes. For example, the Society of Protozoa, founded in 1947, was renamed the International Society of Protistology in 2005. However, the term may persist. Protozoology is a branch of biology dealing with protozoa. Protozoa are eukaryotes that belong to a group characterized as unicellular, most of which are motile and heterotrophic. In the five kingdom schemes for classifying organisms, they belong to taxonomic groups within the kingdom of protists and are usually classified based on the means of transport of flagellates, amoebas, sporozoas, and ciliates. Protozoology studies these organisms in terms of taxonomy, morphological features, medical significance, and more. People who specialize in this particular area of biology are called protozoologists. One of these prominent protozoologists is Stanislav von Prowazek. He is an Austrian protozoologist and parasitologist, known for his work and head of the Protozoenkunde division of the Imperial Health Department in Berlin. He first showed that special stage in the body of a rat host. However, the term protozoology is less common than it used to be, and protozoology prefers the scientific study of organisms that have come to be called protozoa along with eukaryotes such as algae and other plants. Please note. Historically, protozoa have been divided into four major groups: amoebas, flagellates, ciliates, and sporozoa. The distinguishing features between the groups were based on motility (i.e., amoeba, flagella, and cilia). Parasitic protozoa were a heterogeneous group that produced spores at one stage of their life cycle and exhibited "sliding" motility. In addition to the form of asexual reproduction, many protozoa also exhibit sexual reproduction. This sexual reproduction may involve the production and fusion of gametes in a process similar to that of higher organisms. In summary, protozoa are unicellular eukaryotic microorganisms.