Physiologically, the antennal mechanosensory setae on the planktonic copepods are characterized by unusually high sensitivity (<10 nm displacements), fast reaction times (<1 msec latency) and phase locking to high frequencies (1 to 2 kHz). This extraordinary collection of responses makes them highly successful in marine and freshwater environments, able to escape predation and to successfully find food and mates. These physiological properties can be expected to arise from specialized cellular structures.

These images were taken with electron microscopes. Electron microscopes use a beam of electrons as their source of illumination; light microscopes use a beam of light. Light microscopes have glass lenses to control and focus the beam of light; electron microscopes have electromagnetic lenses to control and focus the beam of electrons. A beam of electrons has a shorter wavelength than a beam of light, so it is possible to see things at a higher magnification and resolution.  They were originally in black and white, but are colorized for fun and to highlight various features. That means working with them at high resolution, sometimes painting each individual hair!