Most vertebrates (including humans) have several classes of cones, each sensitive to a different part of the visible spectrums of light.

They are also able to perceive finer detail and more rapid changes in images because their response times to stimuli are faster than those of rods.

Being color blind can change this, and there have been some verified reports of people with four types of cones, giving them tetrachromatic vision.

Most vertebrates have several different classes of cone cells, differentiated primarily by the specific photopsin expressed within.

Humans normally have three classes of cones, designated L, M and S for the long, medium and short wavelengths of the visible spectrum to which they are most sensitive.

The CIE 1931 color space is an often-used model of spectral sensitivities of the three cells of a typical human.

[10] Like rods, each cone cell has a synaptic terminal, inner and outer segments, as well as an interior nucleus and various mitochondria.

Photopigments exist as transmembrane proteins within these disks, which provide more surface area for light to affect the pigments.

Neither rods nor cones divide, but their membranous disks wear out and are worn off at the end of the outer segment, to be consumed and recycled by phagocytic cells.

The ratio of M and L cones varies greatly among different people with regular vision (e.g. values of 75.8% L with 20.0% M versus 50.6% L with 44.2% M in two male subjects).

At lower light levels, where only the rod cells function, the sensitivity is greatest at a blueish-green wavelength.