Paramecium Bursaria showing symbiosis with green algae 草履蟲綠藻共生

Paramecium bursaria is a species of ciliate protozoan that has a mutualistic symbiotic relationship with green algae called Zoochlorella. The algae live inside the Paramecium in its cytoplasm and provide it with food, while the Paramecium provides the algae with movement and protection. P. bursaria is 80-150 μm long, with a wide oral groove, two contractile vacuoles, and a single micronucleus as well as a single macronucleus. P. bursaria is the only species of Paramecium that forms symbiotic relationships with algae, and it is often used in biology classrooms both as an example of a protozoan and also as an example of symbiosis. Shown magnified 400X using a combination of darkfield and phase contrast lighting.

草履蟲（Paramecium）屬於原生動物門，纖毛蟲綱。
草履蟲的身體呈圓筒形，前端較圓，中後部較寬，後端較尖，平面看形狀像倒置的草底鞋，故名。全身縱行排列布滿大致同長細的纖毛，以行動。身體一側有一條自前端斜向腰部的凹入小溝，稱口溝，溝底有口，溝內有較為長密的纖毛，可鼓起水渦而攝取水中細菌及其他有機物作為草料，常見的是大草履蟲（p.caudatum），有一大核，一小核。 世界上最小、最簡單的動物之一，生活在有淡水的地方，肉眼無法看見。

Amazing Microscopic video! Paramecium Bursaria showing symbiosis with green algae.