Wikipedia
Gregarinasina
The gregarines are a group of Apicomplexan protozoa, classified as the Gregarinasina or Gregarinia. The large (roughly half a millimeter) parasites inhabit the intestines of a large number of invertebrates. They are not found in any vertebrates. However, gregarines are closely related to both Toxoplasma and Plasmodium, which cause toxoplasmosis and malaria, respectively. Both protists use protein complexes similar to those that are formed by the gregarines for gliding motility and invading target cells. This makes them an excellent model for studying gliding motility with the goal of developing treatment options for toxoplasmosis and malaria.