SOPHISTICATED ALIEN-LIKE SYSTEMS
Octopus, squid, and cuttlefish are all cephalopods, marine invertebrate molluscs that are closely related to other ocean creatures, like sea slugs, snails, and oysters. Cephalopods have evolved a number of unique and highly sophisticated alien-like systems, including 1) adaptive skin color that allows them to communicate and rapidly camouflage themselves, 2) fast agile swimming by jet propulsion and fin flapping, and 3) flexible, stretchable, prehensile arms, tentacles, and suckers that interrogate and taste the world around them. The "world's smallest" cephalopod, the pygmy squid Idiosepius, is shown in the video below, and is an adult female less than two centimeteres in length, while adult males can be as small as half a centimeter.
Human vs Octopus
PARALLEL COMPLEX BRAINS AND BEHAVIOR
Humans and octopuses represent two major groups of animals, vertebrates and cephalopods. From simple beginnings, the two groups evolved independently into large, fast-moving, visual predators, think “fish” vs “nautilus”, around the same time in ancient Cambrian and later oceans. Facing similar pressures in their early evolution, the two groups engineered both novel and convergent structures and systems related to their top predator lifestyles. For instance, fish evolved swimming by body undulation (novel) and fins (convergent), while cephalopods evolved swimming by jet propulsion (novel) and fins (convergent). Similarly, both groups have a multi-chamber heart and high-pressure circulatory system that enables rapid movement of blood and oxygen to muscles. However, vertebrates have only a single heart, while cephalopods have three, one for the body and one for each of the two gills, which function like lungs in oxygenating the blood. Strikingly, both groups evolved image-forming camera-like eyes and a large, centralized, highly complex brain but the brain architecture in the two lineages is distinct. In humans and vertebrates, nearly all processing is done in the brain and to a lesser extent the spinal cord, while in octopus one third is in the brain while two thirds is in the arms. In a way, the octopus has a brain and eight spinal cords.