This scientific illustration depicts the southern blue-ringed octopus (Hapalochlaena maculosa) in a realistic style, highlighting its distinctive pattern of luminous rings and vibrant coloration. Known for its potent neurotoxin, this species is small in size but extremely venomous and dangerous to humans. On the left is a detailed image of its brain, demonstrating the complex structure of the nervous system and the high level of intelligence typical of cephalopods. The composition combines art and science, providing an in-depth and detailed look at the anatomy of this amazing mollusk. The background sketches enhance the analytical approach, turning the illustration into a valuable tool for studying the biological, anatomical and evolutionary features of the species.