Seta

A simple or robust extension of the diatom valve. The plural form is setae. Setae are more elongate than spines and are found in the genera Chaetoceros and Bacteriastrum. They join frustules together to form chains and maintain the buoyancy of colonies in a planktonic environment.

7  Chaetoceros
Image Credit: Sarah Rushforth
Colony of living Chaetoceros elmorei, with many setae extending from the frustules.
Chaeto 11 Oct2012 4 E
Image Credit: Karthick Bala
Scanning electron micrograph of a single valve of Chaetoceros, showing the interior of the valve with two setae extending from it.
Chaeto 11 Oct2012 3 E
Image Credit: Karthick Bala
Scanning electron micrograph of several broken setae, no longer attached to a valve.