Sinistral and dextral

Sinistral and dextral, in some scientific fields, are the two types of chirality ("handedness") or relative direction.

Other disciplines use different terms (such as dextro- and laevo-rotary in chemistry, or clockwise and anticlockwise in physics) or simply use left and right (as in anatomy).

Very few species show an even mixture of dextral and sinistral individuals (for example, Amphidromus perversus).

[2] The most obvious characteristic of flatfish, other than their flatness, is their asymmetric morphology: both eyes are on the same side of the head in the adult fish.

Primitive spiny turbots include equal numbers of right- and left-sided individuals, and are generally more symmetric than other families.

Left: The normally sinistral (left-handed) shell of Neptunea angulata , a species of sea snail (now extinct) found mainly in the Northern Hemisphere.
Right: The normally dextral (right-handed) shell of Neptunea despecta , a similar species found mainly in the Southern Hemisphere.
European flounder , like other flatfish , experience an eye migration during their lifetime, making them asymmetric.
Schematic illustration of the two strike-slip fault types. The view is of the Earth's surface from above.