TOEFL Formatı Test 4

Passage

The octopus is widely regarded as one of the most intelligent invertebrates on Earth. Despite having a brain that is structurally very different from those of mammals, octopuses exhibit remarkable problem-solving abilities, short- and long-term memory, and behavioural flexibility. In laboratory settings, they have been observed opening screw-top jars to reach food, navigating complex mazes, and even using tools — such as carrying coconut shells to later assemble into shelters. What makes octopus intelligence particularly fascinating is the distribution of their nervous system. Approximately two-thirds of an octopus's neurons are located not in its brain but in its arms, each of which can independently taste, touch, and make basic decisions. This decentralised nervous system allows octopuses to coordinate complex movements while their brain focuses on higher-level processing. Researchers have noted that a severed octopus arm continues to respond to stimuli for up to an hour, suggesting a significant degree of autonomous neural activity. Octopuses also display impressive social learning capabilities. In one well-documented experiment, untrained octopuses learned to select the correct-coloured ball simply by watching a trained octopus perform the task — a form of observational learning previously thought to be limited to vertebrates. Furthermore, octopuses possess an extraordinary ability to change their skin colour, texture, and even shape within milliseconds, primarily for camouflage but also, some researchers believe, for communication. These creatures challenge many long-held assumptions about the nature of intelligence and demonstrate that complex cognitive abilities can evolve along very different biological pathways.