The second lecture is about eyes. Alexander Yakushev has a quite unusual diction and style of presenting the material – it’s somewhat emotional and with intonations, but essentially the lecture is very interesting.
However, it’s unclear where the lecturer got some of his information. For example, it is known that since the octopus’s eye evolved along a different evolutionary path, its color vision (as well as that of squid) is either absent or uses a different, still unclear principle compared to, say, mammals. It used to be believed that it sees with its skin (I have an unfinished book called The Soul of an Octopus by Montgomery lying in my phone – that’s exactly what is written there). Humans have three types of rods and cones, tuned to blue, green and red, whereas the octopus has only one type of photoreceptors, tuned to brightness (but it has many of them and its vision is sharper). How do we know it can distinguish colors? Because many species, like the chameleon, can replicate the pattern of their surroundings to blend in. So, Alexander Yakushev claims that their unusual pupil pulsates, and light reaches the retina at different angles. I never read about pulsation, but I did read that octopus uses an unusual eye shape (U or W shapes). Eventually, the eye focuses light waves of certain wavelengths on different parts of the retina. Color is determined through the brain processing different “snapshots” from the eye. Pulsation – is also an interesting theory, but usually people insert at least some reference to supporting works in their slides.
But overall, the lecture is short, and interesting with a set of facts about the nature of the eye.
Hi, I'm Rauf Aliev. 