Scientists Uncover the Secret Behind a Deep-Sea Creature’s Rare Ability

Deep-sea dragonfish (Malacosteus niger) possess a rare biological ability to produce and perceive red light, according to reporting by Illustrerad Vetenskap on June 10, 2026. This mechanism allows the fish to hunt and communicate in the deep ocean while remaining invisible to most other marine species that only perceive blue and green light.

Researchers have identified the specific biological secret behind this capability: the fish uses a chlorophyll-derived sensitizer to detect red light. This compound, acquired through the dragonfish’s diet, allows its eyes to react to longer wavelengths of light that are typically invisible to deep-sea organisms.

How does the dragonfish see red light?

The dragonfish utilizes a chemical compound derived from chlorophyll to expand its visual spectrum. According to the research highlighted by Illustrerad Vetenskap, the fish consumes copepods that have previously eaten phytoplankton, absorbing the chlorophyll-based pigments into its own retinal cells.

These pigments act as sensitizers, absorbing red light and transferring the energy to the fish’s visual pigments. This process enables the dragonfish to see red light even in the absolute darkness of the bathypelagic zone, where sunlight cannot penetrate.

Most deep-sea creatures rely on bioluminescence in the blue and green spectrums because these wavelengths travel furthest through seawater. The dragonfish, however, produces its own red light via specialized organs called photophores located under its eyes.

Why is red light an evolutionary advantage?

The ability to operate in the red spectrum functions as a private communication channel and a stealth hunting tool. Because almost all other deep-sea animals lack the pigments to see red light, the dragonfish can illuminate its prey without alerting them to its presence.

This creates a biological “invisible flashlight” effect. The dragonfish can scan the surrounding water for prey and signal to potential mates while remaining undetected by predators that only see blue or green light.

This contrast in visual capabilities represents a significant divergence from the standard evolutionary path of deep-sea organisms. While most species evolved to be more sensitive to the blue light that permeates the ocean, the dragonfish evolved a method to exploit a wavelength that is virtually absent in the natural environment.

How does this compare to other deep-sea bioluminescence?

The dragonfish’s system differs fundamentally from the bioluminescence used by the majority of deep-sea species. Most organisms use a reaction between a light-emitting molecule called luciferin and an enzyme called luciferase to produce blue light.

According to the research, the dragonfish’s red-light production is not just a variation in color but a specialized adaptation involving different chemical pathways and dietary dependencies. This reliance on chlorophyll-derived compounds links the fish’s sensory capabilities directly to the food chain of the upper ocean layers.

• Standard Bioluminescence: Primarily blue/green; visible to most deep-sea species; used for lure and defense.
• Dragonfish Bioluminescence: Red spectrum; invisible to most deep-sea species; used for stealth hunting and private signaling.
• Visual Mechanism: Standard fish use rhodopsin-like pigments; dragonfish use chlorophyll-derived sensitizers.

What does this reveal about deep-sea ecosystems?

The discovery highlights the complexity of nutrient transfer between the ocean’s surface and its depths. The fact that a deep-sea predator relies on chlorophyll—a pigment essential for photosynthesis in sunlight—demonstrates how surface-level biological materials are recycled and repurposed in the abyss.

Researchers suggest that this finding may lead to the discovery of other species with similar “hidden” sensory capabilities. By analyzing the dietary links and chemical compositions of other deep-sea predators, scientists can better map the predatory dynamics of the midnight zone.