More recent studies indicate that it is quite possible that octopuses can see in color. Biologists have been puzzled for decades by the octopus vision paradox. Despite their brightly colored skin and ability to quickly change color to blend into the background, cephalopods such as octopus and squid have eyes with only one type of light receiver, which basically means they only see black and white. Octopuses have large eyes and far superior vision.
When dark, the pupil of the octopus's eye is circular, while in bright light, it compresses into a horizontal slit. Octopuses are not unique in this regard, as several other species are now known to have skin that contains opsins and is sensitive to light. In line with the presence of a single visual pigment, most studies have concluded that Octopus vulgaris is colorblind (Piéron, 1914; Bierens de Haan, 1926; Messenger et al. This is what has generated the theory that octopuses can change from a focused vision style with a narrow range of coverage that is colorblind to a wider panoramic vision style that is fully colored.
Octopuses have dumbbell-shaped pupils that act as prisms, scattering white light and dividing it into its color components. For example, the octopus retina is everted rather than inverted, and is equipped with primary rhabdomeric photoreceptors instead of the secondary ciliary variety found in the retina of the vertebrate eye. This would mean that both the complexity of the human eye and that of the octopus developed independently much later. The primary structures of an octopus's eye are the iris, the lens, the vitreous gel (the mass of the eyeball), the pigment cells, the photoreceptors, the retina, and the optic nerve.
In any case, the octopus certainly has large monocular visual fields, the space in which objects can be seen with a single eye. Expansion of light-activated chromatophores (LACE) independent of the eyes and expression of phototransduction genes in the skin of Octopus bimaculoides. Octopuses are well known for changing the color, pattern and texture of their skin to blend with their environment and send signals to each other, a skill that makes them the envy and inspiration of army engineers trying to develop camouflage devices. The octopus is widely regarded not only as the most intelligent invertebrate, but also as one of the most cognitively advanced animals.
However, it remains to be determined what role polarization sensitivity plays in particular Octopus vulgaris, since most of the evidence in this regard has so far been collected in other cephalopod species. Although convergent evolution made the human eye and the octopus eye quite similar, there are key differences. Only if the pupil is horizontal and, therefore, the orientation of the retinal receptors is fixed in relation to the external world (see section “Retina and visual function) is the octopus able to discriminate stimuli that differ in orientation (Boycott and Young, 1956; Sutherland, 1957, 1963a; Wells, 1960; Young, 1960).
