• Category
  • Length Range
    68-102 µm
  • Width Range
    5.5-6.5 µm
  • Striae in 10 µm



Living cells occur in long chains, connected along their keels. Valves are isopolar, linear to linear-lanceolate and sometimes with slightly undulate margins tapering to narrow apices. The characteristic placement of the keel in the center of the valve distinguishes this genus from others in the Bacillariales. Keel puncta are rectangular, but not regular in shape and number about 6-10 in 10 µm. Striae are distinct, parallel, perpendicular to the keel, and number 19-24 in 10 µm.


Original Description

  • Author
    Gmelin 1788

EMAP Assessment

EMAP Distribution

Bacillaria Paradoxa 40 Copy
Map 40

Response Plots

Bacillaria Paradoxa Copy

Citations & Links


  • Index Nominum Algarum
  • CAS
  • North American Diatom Ecological Database
    NADED ID: 76001

Cite This Page

Kociolek, P. (2011). Bacillaria paradoxa. In Diatoms of North America. Retrieved July 16, 2018, from https://diatoms.org/species/bacillaria_paradoxa


The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Bacillaria paradoxa from all the stream reaches where it was present. Note that the relative abundance scale is the same on each plot. Explanation of each environmental variable and units are as follows:

ELEVATION = stream reach elevation (meters)
STRAHLER = distribution plot of the Strahler Stream Order
SLOPE = stream reach gradient (degrees)
W1_HALL = an index that is a measure of streamside (riparian) human activity that ranges from 0 - 10, with a value of 0 indicating of minimal disturbance to a value of 10 indicating severe disturbance.
PHSTVL = pH measured in a sealed syringe sample (pH units)
log_COND = log concentration of specific conductivity (µS/cm)
log_PTL = log concentration of total phosphorus (µg/L)
log_NO3 = log concentration of nitrate (µeq/L)
log_DOC = log concentration of dissolved organic carbon (mg/L)
log_SIO2 = log concentration of silicon (mg/L)
log_NA = log concentration of sodium (µeq/L)
log_HCO3 = log concentration of the bicarbonate ion (µeq/L)
EMBED = percent of the stream substrate that is embedded by sand and fine sediment
log_TURBIDITY = log of turbidity, a measure of cloudiness of water, in nephelometric turbidity units (NTU).
DISTOT = an index of total human disturbance in the watershed that ranges from 1 - 100, with a value of 0 indicating of minimal disturbance to a value of 100 indicating severe disturbance.