The deep-sea rattail is a master of the abyss with a musical secret

Nature · Published 3 October 2026 Swipe more like this →

In short: Abundant across the world's oceans, grenadiers are deep-sea survivors that thrive in extreme darkness. These fish, often called rattails, possess specialized adaptations including light-producing organs and the ability to strum their swim bladders to create sound. Despite their prevalence, much of their life history remains a mystery to science.

Belonging to the family Macrouridae, grenadiers are among the most common inhabitants of the deep sea, potentially representing up to 15% of the total deep-sea fish population. They are found from the Arctic to the Antarctic, occupying depths ranging from about 200 to 7,000 meters. While most species are benthic, preferring the ocean floor, some are known to inhabit the midwater. Their physical form is distinct, featuring a large head and a slender, tapering body that ends in a thin, rat-like tail—a characteristic that gives the family its common name.

Survival in the abyss requires specialized sensory equipment. Grenadiers rely on a well-developed lateral line system, supplemented by numerous chemoreceptors on their heads and lips, and sensitive barbels under their chins. Perhaps most intriguing is their ability to produce sound. Benthic species possess unique muscles attached to their swim bladders, which they are thought to use like a drum to communicate, potentially aiding in courtship or locating mates. Some species also feature photophores, light-producing organs located along their abdomens, which may serve as another tool for navigating the dark.

The life cycle of these fish is as elusive as their habitat. They produce over 100,000 tiny, lipid-buoyant eggs that rise to the thermocline to develop. Juveniles then gradually migrate to deeper waters as they age. While some species, like Coryphaenoides armatus, are believed to be semelparous—dying after a single spawning event—others can live for 56 years or more. Because they generally exhibit low resilience, researchers warn that commercial fishing efforts could easily lead to population collapse, especially since the fish are often considered unpalatable, making the environmental cost of such fisheries particularly difficult to justify.

The family is remarkably diverse, containing 28 extant genera. They act as both apex predators and scavengers, feeding on a generalist diet of crustaceans, smaller fish, and occasionally cephalopods. They are frequently found near structural oases like hydrothermal vents and shipwrecks, where they may congregate in large schools. Despite their abundance, the lack of recovered larvae means that much of their early development remains a subject of ongoing scientific inquiry.

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