The ocean's most intelligent fish possess a brain-to-body ratio unlike any other

Nature · Published 23 October 2026 Swipe more like this →

In short: Manta rays are often overshadowed by sharks and whales, but these graceful giants may be the ocean's secret intellectuals. Due to having the greatest brain-to-body ratio among extant fish, these animals display intricate actions and keen perception hinting at a refined inner existence under their fin-like appendages.

Manta rays are massive marine wanderers, with some individuals weighing up to two tons. Their physical presence is defined by impressive wing spans reaching between 12 and 23 feet, giving them an appearance similar to birds soaring through the water. Despite their size, they are filter feeders, utilizing rows of small plates in their mouths to strain microscopic plankton from the sea. What sets them apart from other fish is their neurological complexity. They possess the largest brain-to-body ratio of any living fish species, a trait that correlates with surprisingly complex behaviors and high levels of awareness. Observations have shown them interacting curiously with humans; some individuals have even been known to allow scuba divers to ride on their backs.

This level of interaction suggests a cognitive depth that is only recently beginning to receive scientific and public attention. Conservation efforts for the manta ray are relatively new compared to those for sharks or dolphins. However, they face significant threats from overfishing and tourism. In places like Sri Lanka, they are targeted specifically for their gill rakers—feather-like mesh structures used in traditional Chinese medicine—while their meat is considered a low-value commodity. Because of these pressures, organizations like the Manta Trust were established as recently as 2011 to provide global protection and research for these intelligent giants.

The study of mantas involves tracking them across vast distances to hotspots such as Mexico, Micronesia, the Maldives, and Australia’s Great Barrier Reef. Researchers look for specific behaviors like rare mating rituals and feeding frenzies, particularly during events like the southwest monsoon season in the Indian Ocean, where trade winds upwell microscopic nutrients that sustain massive schools of baitfish and mantas alike.

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