Julian Partridge

Julian Partridge (born February 1959) is a marine biologist and neuroethologist. His work primarily focuses on animal sensory systems, with a notable focus on deep-sea organisms. He is considered a leading expert in deep-sea adaptations and biology, and his discovery of a fish that utilizes reflective optics to see was groundbreaking in the scientific community.

Early Life Julian Partridge was born in the United Kingdom in February 1959. After attending several secondary schools across Singapore and the United Kingdom, he attended the University of Bristol in Bristol, England.

Career After earning his bachelor's degree in zoology from the University of Bristol, he returned to the same institution to obtain his PhD in zoology. After capturing a single specimen of the Spookfish (Dolichopteryx longipes) over a trench in the South Pacific, they photographed and studied the eye extensively. The team found that it is separated into two parts: the main eye cylinder and a larger lateral diverticulum. Inside of each diverticulum, they visualized a mirror that appeared to provide a focused image over most of the retina. This was an important cross-disciplinary discovery, particularly in Partridge's field of bio-inspired robotics. Understanding how the vision system in stomatopods can resist responding to optical illusions could be valuable to a robotic vision system that needs to maintain visual stability or track objects while moving with an unpredictable trajectory or over complex terrain. This experiment was and still is a leading indicator of the possibilities that the field of bio-inspired robotics can offer to automation and technology.

Far-Red Vision in Dragonfish Partridge performed extensive investigation into the visual pigments and bioluminescent properties of dragonfish, a deep-sea fish found in tropical North Atlantic waters. Chemical isolation and testing of the fish's visual pigments revealed that it has one highly optimized for far-red light, at about 700 nanometers (nm) on the electromagnetic spectrum. Most marine animals have pigments optimized for blue light, around 480 nm, because that wavelength penetrates the deepest into the ocean. He also found that the dragonfish happens to be bioluminescent, emitting that very same wavelength of light. This gives the fish a significant hunting advantage, since it can light up its prey in the water without the prey seeing that it's being illuminated. Furthermore, until this discovery it was a previously unknown adaptation of deep-sea creatures. Other organisms evolved to detect the bioluminescence of their prey or predators, but this fish has evolved to be its own beacon.

Bioluminescence is another adaptation that plays a crucial role in deep-sea environments. It is a primary tool for communication, camouflage, and hunting. Many deep-sea organisms have evolved visual pigments that allow them to detect the bioluminescence of their surroundings and of other organisms that may be nearby. Additionally, the visual pigments of these organisms are finely tuned to pick up the wavelengths of light most common in the deep sea, usually in the blue light spectrum. Depending on the depth at which the organism lives, the pigments may have evolved differently, which is indicative of the true complexity of visual adaptations.

Many organisms in the deep sea have also evolved specialized eyes that allow them to coexist properly with other species within a common ecological niche. Predator species often have forward-facing eyes, while prey species tend to have wider, lateral eyes to provide a broader field of vision. Some species can also rotate their eyes to adjust to their environment, while others have reflective layers that allow for light sensitivity adjustment.