The elephantfish is an ancient, electro-sensing survivor with a genome smaller than ours

Nature · Published 3 October 2026 Swipe more like this →

In short: With a bizarre, plough-shaped snout and a cartilaginous skeleton, the elephantfish is a living relic. As the oldest group of jawed vertebrates, these creatures offer a rare window into early evolutionary history. They navigate the ocean floor using electric fields, yet their unique biology remains largely overlooked by modern conservation.

The Callorhinchidae, or plough-nosed chimaeras, are the sole survivors of their genus, representing the oldest living group of jawed chondrichthyes. Unlike their relatives—sharks and rays, which belong to the subclass Elasmobranchii—these fish are holocephalans. Their anatomy reveals this deep evolutionary split: while sharks have jaws loosely attached to their skulls, the elephantfish possesses a jaw fused directly to its cranium. Furthermore, they lack the tough, abrasive scales typical of sharks, sporting smooth skin and a protective operculum over their gill slits instead.

These fish are masters of the ocean floor, utilizing a flexible, fleshy snout that acts as a sensory organ. This 'trunk' detects movement and electric fields, allowing them to hunt for molluscs and small invertebrates in muddy or sandy substrates. Because they are relatively slow swimmers compared to teleosts, they rely on this specialized sensing to locate prey rather than speed. Their brain structure reflects this priority, with a larger cerebellum than forebrain and an encephalization quotient of 1.1, significantly lower than the human average of 6.

Found only in the Southern Hemisphere, these fish inhabit subtropical and temperate waters. They are the only chimaeras that still occupy shallow neritic zones, a habitat type that most other chimaeriforms abandoned for the deep sea at the start of the Cenozoic. Despite their evolutionary significance, they face mounting pressures. In regions like South America, they are heavily fished, with Callorhinchus callorynchus currently listed as Vulnerable. While they are not yet the focus of major global conservation efforts, their status as a research model—thanks to having the smallest genome among all chondrichthyans—makes them an invaluable subject for understanding the development of jawed characteristics in vertebrates.

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