Stentor amethystinus

Stentor amethystinus is a single-celled eukaryote. It is often 1.0 millimetre (0.04 in) long and is found in freshwater ponds and lakes. Algae live in symbiosis with Stentor amethystinus, providing food for the ciliate, which then protects the algae.^[1] Unlike many of its relatives, Stentor amethystinus is red-violet in color, due to the chemical amethystin.^[2] The chemical amethystin is structurally similar to the chemical stentorin, which belongs to Stentor coeruleus.^[3]

Stentor amethystinus
Scientific classification
Domain:	Eukaryota
Clade:	Sar
Clade:	Alveolata
Phylum:	Ciliophora
Class:	Heterotrichea
Order:	Heterotrichida
Family:	Stentoridae
Genus:	Stentor
Species:	S. amethystinus
Binomial name
Stentor amethystinus Leidy, 1880