SEM of Giardia, ventral view

Scanning electron micrograph of ventral surface of Giardia, computer-coloured purple on blue. This parasitic protozoan inhabits the human small intestines. It is usually harmless, but may cause diarrhoea (giardiasis). It has two nuclei, four pairs of undulipodia, and two sucking discs for attaching to the intestine wall.