Ciliates, sporozoans and Lab 1

Ciliates have a body covered with cilia and have a large and a small nucleus. The name comes from their first discovery in hay infusion. Paramecium (0.1–0.3 mm) looks like the sole of a slipper and swims blunt end first. At the bottom of a groove on its side is the mouth opening: cilia sweep bacteria into the gullet, where a food vacuole forms and circulates with the cytoplasm flow, and the waste leaves through a hole at the rear. Two contractile vacuoles contract in turn to remove excess water. In asexual reproduction the nuclei divide, the body narrows in the middle and splits in two. Sporozoans (over 4000 species) are all parasites: they have no organelles for movement, digestion or excretion. The malaria parasite is passed to humans by the malaria mosquito; it multiplies in red blood cells, and when it destroys them and enters the blood plasma, a malaria attack (fever) begins. The textbook also puts Nosema, which infects silkworms and honey bees, in this group, but today scientists place it in a separate group close to fungi, the microsporidia.