I took a sample of a small plant from a rock basin at the shore of the Gulf of Thailand, after returning from a snorkeling trip. The plant leaves were covered with various Peritrichs (single-cell organisms with cilia around their oral openings) and Suctorians (single-cell predators with spines that immobilize their prey then suck out their endoplasm).

What’s most fascinating in this video is the first set of clips, showing Vaginicola and Thuricola, two related genera. They look exactly alike. The only way to tell them apart is that Thuricola builds a one-way valve inside its lorica (the protective sleeve it lives inside). The valve acts as protection against intruders when Thuricola has retreated inside its home. Watch Thuricola push through a valve at 1:22 in the video.

At 0:48 watch for the two Vaginicola in one lorica. The smaller one has fully retreated, and is undergoing replication.