portrait

Description:

Didinium (die-din-ee-um) nasutum is an oval ciliate ranging in size from 80 microns to 200 microns, but is usually 120 - 150 microns long. This ciliate lives in freshwater habitats and is frequently seen in pond samples. It has two conspicuous bands or girdles of cilia (pectinellae); one round the front pointed end and one band just below the middle of the cell. The oral dome at the anterior end extends as a snout or nose. This feature gives it its species name, 'nasutum' - meaning 'nose'. Didinium can easily be confused with dividing cells of a similar genus with only one anterior girdle but formed a second girdle in the mid-body during cell division. This is a slightly squashed specimen. The lateral view shows the two ciliary girdles and the oral dome equipped with hundreds of extrusomes. The cell is 126 X 108 microns. Differential interference contrast.