Drawing

Description:

Choanoeca perplexa Ellis, 1930. Choanoflagellate cell, solitary, piriform, neck considerably elongated, length of cell (extended): 4.5 to 7 microns Lorica vasiform, more or less closely investing cell, sessile or with short peduncle. Diameter of collar at mouth: 12-18 microns at the normal angle of expanse, about 75degrees, the extreme angles of expanse are 10 degrees and 90 degrees - that is, at right angles with major axis of the cell. Flagellum entirely absent in normal adult cell, but temporarily produced, just before cell-fission, for locomotion. Nucleus normal. One contractile vacuole, basal. The collar can rapidly transform from maximum to minimum expanse, the act strongly resembling the sudden closing of an umbrella. The shape of the lorica is that of a short-necked vase with a slightly everted lip and globular body tapering, more or less abruptly, to a point. The peduncle is obviously an extension, 2-6 microns long of the lorica.