Biflagellated cells enclosed within an organic lorica, usually vase shaped. Solitary of colonial, if colonial may be arborescent or ball-shaped. Lorica may attach directly to substrate or have stalk. Anterior margin of cell raised on one side to form a collar. This forms part of the ingestion area. Cells may retract into their lorica by action of the recurrent flagellum, anterior flagellum coils up. Sometimes and incorrectly spelled Bicoeca. About 40 species, freshwater and marine. Type species: B. lacustris, James-Clark, 1867.

Depth range based on 66 specimens in 8 taxa.
Water temperature and chemistry ranges based on 66 samples.

Environmental ranges
  Depth range (m): 0 - 75
  Temperature range (°C): -1.300 - 4.949
  Nitrate (umol/L): 1.991 - 5.646
  Salinity (PPS): 33.551 - 34.929
  Oxygen (ml/l): 7.011 - 8.654
  Phosphate (umol/l): 0.295 - 0.581
  Silicate (umol/l): 3.180 - 4.885

Graphical representation

Depth range (m): 0 - 75

Temperature range (°C): -1.300 - 4.949

Nitrate (umol/L): 1.991 - 5.646

Salinity (PPS): 33.551 - 34.929

Oxygen (ml/l): 7.011 - 8.654

Phosphate (umol/l): 0.295 - 0.581

Silicate (umol/l): 3.180 - 4.885
 
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