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Gyrosigma
Gyrosigma may not look like they're symmetrical at first glance, but in fact they are: their "S" shape is called "sigmoid," and it displays symmetry down its central axis. These biraphid diatoms are highly motile, and live on and in the bottom sediments of lakes and rivers.
G. attenuatum
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Cells are 130-225 µm in length, 20-28 µm in width.
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Rows of striae per 10 µm are 10-12 longitudinal, 12-14 transverse (perpendicular to raphe).
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Valves are long, narrow, and sigmoidal.
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The best way to tell apart G. attenuatum from G. acuminatum is by size and striae: G. attenuatum's size range is larger, and its longitudinal striae are more pronounced than its transverse striae. In other words, on G. attenuatum it looks like there are mostly just lines going from tip to tip, rather than lines forming a grid pattern.
For more information, visit diatoms.org here.
![A3m1 Gyrosigma attenuatum_edited](https://static.wixstatic.com/media/a0fe14_196ec7fa5ac5450685c4d2edaf424a3a~mv2.png/v1/fill/w_49,h_38,al_c,q_85,usm_0.66_1.00_0.01,blur_2,enc_auto/a0fe14_196ec7fa5ac5450685c4d2edaf424a3a~mv2.png)
A3m1 Gyrosigma attenuatum_edited
![A5m1 Gyrosigma attenuatum (closeup)](https://static.wixstatic.com/media/a0fe14_bb3c7555628b4832834d003ca53b13a6~mv2_d_2448_1920_s_2.png/v1/fill/w_49,h_38,al_c,q_85,usm_0.66_1.00_0.01,blur_2,enc_auto/a0fe14_bb3c7555628b4832834d003ca53b13a6~mv2_d_2448_1920_s_2.png)
A5m1 Gyrosigma attenuatum (closeup)
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