Page 78 - Algae Anatomy, Biochemistry, and Biotechnology

Anatomy 61

FIGURE 2.33 Spider web scale of the flagellar membrane of Mamiella gilva.

160 nm, and a long, thin distal part of 650 nm, and the apical hairs possessing a long thick base and
a very short, thin tip. In Nephroselmis and Tetraselmis there is a single hair type divided into two
regions of roughly the same length (0.5 mm).
Unlike tubular hairs, simple, nontubular hairs are not differentiated into regions; they are thin
and very delicate, probably consisting of a single row of subunits. These hairs occur in a variety of
groups, but are unique in the two divisions of Euglenophyta and Dinophyta, whose hairy coverings
share certain features not known to occur in any other algal group.
In Euglenophyta, long, simple hairs are arranged in a single row on the emergent part of the
flagella. In genera with two emergent flagella, the hair covering is similar on the two flagella. In
Euglena gracilis these long hairs consist of a single filament 3–4 mm long, with a diameter of
10 nm, while in Eutreptiella gymnastica, they are 4–5 mm long and assembled in unilateral
bundles. In addition to these long hairs, euglenoid flagella carry a dense felt of shorter hairs,
which in Euglena are approximately half as long and half as thick as the long hairs. These
short hairs, precisely positioned with respect to each other and to axonemal components,

FIGURE 2.34 Transmission electron microscopy image of the long trailing flagellum of Ochromonas danica
in both longitudinal (a) and transverse sections (b), showing the tripartite hairs. (Bar: 0.25 mm.)