The cylindrical cells of these organisms are linked together to form long filaments that exhibit high sedimentation rate due to the frustule
which is denser than the surrounding water (Wolin and Duthie, 1999).
A guide to the morphology of the diatom frustule
with a key to the British freshwater genera.
Cell solitary frustule
twisted along the apical axis, panduriform; keeled raphe in each valve; plastids two and large.
Natural counting units were defined as one unit for each colony, filament, diatom frustule
(regardless if colonial or filamentous) or unicellular algae.
samples for microscope analysis were processed according to Parsons et al.
Ultrastructure of the frustule
of Urosolenia species from the colombian and peruvian amazon: U.
Colony and frustule
morphology of three tube-dwelling diatoms from eastern Canada.
Features Observed Weber (1970) Chloroplast 1-2 several Frustule
diameter ([micro]m) 3-4,5 3-4 Pervalvar axis ([micro]m) 6-10 4-8 Areolae in 10 [micro]m 8 - Number of processes 5 -7 5-8 Rimoportula 1 - Features Hasle & Evensen Belcher & Swale (1976) (1978) Chloroplast Frustule
diameter ([micro]m) 1-2 (4) 1-2 Pervalvar axis ([micro]m) 3-4 3-4 Areolae in 10 [micro]m - 6-10 Number of processes - 8 Rimoportula 6-8 5-6 1 1
Diatoms are a unique algal group because they are surrounded by a hard, silica-rich shell called a frustule
that often has an incredibly intricate and delicate structure.
As has been known for more than two centuries, this covering, or frustule
, consists of two halves (the valves), one of which overlaps the other like the lid on a box.
The ability of juvenile abalone to ingest algae depends on the size of the abalone in relation to the algal cell size, the attachment strength of the alga to the substratum, and the strength of the algal cell wall or the outer frustule
of diatoms (Kawamura et al.
Diatoms have an external skeleton of silicon dioxide (silica, SiO2) called a frustule
, formed of two pieces (theca, plural thecae) that fit together and have small pores on their surface that allow the exchange of substances between the cytoplasm and the exterior.