Squid as a Model Organism - Part 3: Ocular Morphology and its Implications in Biomimicry for Human Ophthalmology

The distinctive feature of cephalopods is their lack of scales, possession of eight arms and two long tentacles, with considerable diversity in shape, size, and habitat. Giant and colossal squids represent some of the largest marine creatures. Giant squids, in particular, are exceptionally captivating beings with unique characteristics that allow them to thrive in the incredibly dark depths of the oceans. Despite their large size, these cephalopods are agile swimmers, capable of sudden changes in direction. Vision is the primary sense for cephalopods, enabling them to perform these rapid movements. The giant squid (Architeuthis) has the largest eyes among marine and terrestrial animals, constituting a significant percentage of its weight and volume. These large eyes have captured the attention of biologists, leading to investigations into the anatomy, physiology, and histology of the cephalopod eye. It is noteworthy that the highest concentration of neural cells in the brain is found in the optic lobes of the giant squid, emphasizing the importance of vision in its life in dark and formidable habitats. In this review, we delve into the evolution, histology, structure, and physiology of the giant squid’s vision, followed by a comparative analysis with human optics.