Looking inside the aquarium, i moved closer to make sure it was a live octopus inside a bottle. I wondered how he was able to get inside a bottle then realized something moved. His slit-shaped pupil blinked and then finally I realized it was the octopus eye! :)
Octopuses are characterized by their eight arms (as distinct from the tentacles found in squid and cuttlefish), usually bearing suction cups. These arms are a type of muscular hydrostat. Unlike most other cephalopods, the majority of octopuses – those in the suborder most commonly known, Incirrina – have almost entirely soft bodies with no internal skeleton. They have neither a protective outer shell like the nautilus, nor any vestige of an internal shell or bones, like cuttlefish or squid. A beak, similar in shape to a parrot's beak, is the only hard part of their body. This enables them to squeeze through very narrow slits between underwater rocks, which is very helpful when they are fleeing from morays or other predatory fish. The octopuses in the less familiar Cirrina suborder have two fins and an internal shell, generally reducing their ability to squeeze into small spaces. From wikipedia Free Encyclopedia.
Although the eyes of the octopus, and of other cepaholopds, and the eyes of vertebrates have evolved entirely independently, each has a retina, a cornea, an iris, a lens, and a fluid-filled interior. These similarities of structure, despite different origins, provide a classic example of biological convergence. However, the cephalopod and vertebrate eyes are also very dissimilar in some respects. For example, the photoreceptor cells in the eye of the octopus point toward the incoming light whereas our own rod cells and cone cells point backwards and absorb light reflecting from the back of the eye. Another difference is that the octopus eye, like those of other invertebrates, develops as an invagination, or in-pocketing, of the skin, and not, as in the case of the vertebrate eye, as an extension of the brain. The method of focusing too quite distinct. Cephalopods have a stiff lens of fixed focal length, which is normally focused on objects fairly nearby. The focus is changed by moving the entire lens closer or farther from the retina with the ciliary muscle. We, on the other hand, use our ciliary muscles to change the shape of our eye lens to bring objects at varying distances into focus. From The Internet Encyclopedia of Science.
BTW....check this out. This photo has been selected as photo of the week in honor of Paul The Octopus chiqclicks.com/