Final answer:
Zoomastigina refers to a group of flagellated protozoans which includes parasites like Toxoplasma gondii and Trichomonas vaginalis, causing notable infections in humans.
Step-by-step explanation:
Some Zoomastigina, such as Toxoplasma gondii, are prominent parasites that can infect animals and humans. The tachyzoites of Toxoplasma gondii, are typical in their crescent shape with a centrally placed nucleus, and can be identified in a Giemsa-stained smear from peritoneal fluid. On the other hand, the Trichomonas vaginalis protozoan, which causes the most common nonviral sexually transmitted infection known as trichomoniasis, has an undulating membrane and an amoeboid shape when attached to vaginal cells, but appears oval in culture, as described above.