In octopods there is a strip of long rhabdomes just above the equator of the retina. In Loligo, however, the rhabdomes are shortest at the contre of the eye and longest near the periphery. In Sepia there is a strip of longer rhabdomes above the equator but they are longer at the anterior and posterior ends of the strip than at the centre.
In a dark-adapted retina of Octopus the pigment is concentrated at the base of the rhabdomes. It emerges rapidly in the ventral region but only slowly in the central strip. The rhabdomes of all the species studied shorten under illumination.