The Diatom Project: Thallassiosiracae.

The Diatom Project: Thallassiosiracae.

The Diatom Project: Thallassiosiracae.

The Diatom Project: Thallassiosiracae.

The Diatom Project, Figure 76.

Fig 76. (a) A dense community of freshwater epiphytic diatoms. (b), (c) Epilithon from acid oligotrophic rivers. (d) Epilithon from a eutrophic river. (e) Diatoms (Cocconeis) on the episarc of a hydroid. (f) A diatom (Synedra parasitica) epiphytic on a diatom (Nitzschia sigmoidea).

The Diatom Project, Figure 75.

Fig. 75. (a) Example of cleaned oceanic sediment. (b) Epipsammic diatoms from a freshwater lake. (c),(d) Epipsammic diatoms from marine sand. (e) Epiphytes from feshwater Cladophora. (f) Epiphytes from freshwater Phragmites.  

The Diatom Project, Figure 68.

Fig. 68. (a)-(c) Aulocoseira ambigua: (a) initial cell; (b) initial cell beginning to expand; (c) new large-celled filament alongside original-sized ones. (d)-(f) Rhoicosphenia: (d) initial epivalve with transverse perizonial bands of the auxospore; (e) initial epivalve (f) large cell bearing the initial hypovalve (the raphidvalve) and to the left a small original cell. 

The Diatom Project, Figure 64.

The Diatom Project, Figure 55.

Fig 55. Life cycle of a diatom: based on Stephanodiscus except that the position of the auxospore (c) and the formation of motile gametes (a) has not been seen in this particular genus. (d) Auxospore wall breaking open to reveal initial cell. (e) First division of initial cell to form two new normal hypovalves back to back. (f) One of the cells from stage (e) with a normal valve and an initial cell valve. (g) A cell formed following several divisions of (f) (the other cell is not illustrated but will be a replica of (f). (h), (i) Vegetative size reduction. (i) Small cell which will give rise to either the male or female (or+ or -) gametes. 

The Diatom Project, Figure 51F.

Fig. 51(F). Sexual reproduction in pennate diatoms. a, b, Paired cells of Neidium; c, zygotes of Neidium; d, Paired cells of Sellaphora, e, Rare triplet of Cymbella in meiotic prophase; f, Mucilage envelope surrounding 2 zygotes of Cymbella cistula. 

The Diatom Project, Figure 42.

Fig. 42. Resting spores. (a) Leptocylindrus; (b) & (c) Chaetoceros (?).

The Diatom Project, Figure 34.

Fig. 34. The raphe system. (a) Simple slits of Anorthoneis. (b) Internal polar ending, showing ridges on either side of the raphe fissure and the polar helictoglossa in Pleurosigma. (c) Massive internal development of the raphe-sternum in Frustulia. (d) External raphe ending with terminal fissure extending beyond the region of the helictoglossa (arrow). (e) Fibulae subtending the raphe of a Nitzschia. (f) Central raphe endings of Gyrosigma. (g) Internal central raphe endings with ‘helictoglossa-like’ structures in Parlibellus. 

The Diatom Project, Figure 32.

Fig. 32. Ontogenetic asymmetry of the valve in naviculoid diatoms. One side of the raphe-sternum and hence of the valve can be considered primary, in that it is formed first (a). The secondary side is produced later by a different process, involving the fusion of arms extending out from both centre and poles (b), (c). Where the arms fuse, faults often occur in the stria pattern (compare (c) with (d): these are the Voigt discontinuities. Where both polar raphe endings are turned towards the same side, as in most raphid genera, they turn towards the secondary side ((d). see also Fig. 33). (e)-(j) The evolution of the raphe: (e) the araphid ancestor with rimoportulae at each pole: (f)-(h) differentiation of the raphe from one rimoportula at each pole. Note the finer striae associated with the raphe because of its essentially transapical orientation, the rotation of the raphe towards the centre, and the parallel movement of the undifferentiated rimoportulae to an apical position. (i). (j) Abutting of the raphe onto the strenum and final integration into the primary pattern-centre. In (e)-(j) the pattern-centre is shown stippled and the raphe slits are outlined heavily in black (from Mann, 1984b); primary side at right. 

The Diatom Project, Figure 31.

The Diatom Project, Figure 29.

Fig. 29. (a)-(c) Fultoportulae in (a) Thalassiosira. (b) Stephanodiscus. (c)Thalassiosira. (d)-(f) Rimoportulae in (d) Actinocyclus. (e) Pleurosira. (f) Rhabdonema.

The Diatom Project, Figure 26.

I realize that if you're trying to read the text, it can be a bit irritating, since the left margin is cut off a little - remind you of graduate school handouts? 

The Diatom Project, Figure 24.

Hint: To read the text (including description of the 'plates'), just click on the image, and it will increase in size. 

The Diatom Project, Figure 14.

The Diatom Project, Figure 9.

Fig. 9. (a) Epiphytic diatoms attached to an aquatic moss. (b) Diatoms attached to a Cladophora cell. (c) Epipelic diatoms harvested from brackish sediment onto a coverslip. 

The Diatom Project, Figure 8.

Fig. 8. (a) A filament of Melosira cells. (b) A colony of Planktoniella, in which the cells are united laterally by extracellular polysaccharide. (c) Valve view of a Stauroneis cell containing two large plate-like plastids. (d) Odontella showing discoid plastids. (e) Melosira showing dividing plastids.