Glowing shark of the deep. Its belly is dotted with tiny light organs that produce a soft green glow. This camouflages it against the faint sunlight from above. It lives in the dark depths of the continental slope. Rarely seen by human eyes. The visibility is low. The presence is obscure. The adaptation is luminous. The body is small and slender, with a pointed snout and large, green eyes adapted to low light. The skin is dark brown or black, rough to the touch. It is covered in tiny, tooth-like denticles. The fins are small and rounded. The tail is long and slender. A distinctive crest of enlarged scales lines the upper edge. The texture is abrasive. The design is functional. The appearance is sombre. The photophores are concentrated on the belly and the underside of the head. They produce a glow that matches the colour and intensity of the downwelling sunlight. This breaks up the shark's silhouette. From below, the shark appears to disappear. This is counter-illumination. It is a sophisticated form of camouflage found in many deep-sea animals. The invisibility is active. The strategy is passive. The survival depends on light. It acts as a predator of the deep. It hunts small fish, squid and crustaceans near the seafloor. It uses its large eyes to spot prey in the dim light. When it attacks, it is fast and decisive. It is also preyed upon by larger deep-sea sharks and fish. The role is dual. The risk is constant. The food web is complex. The position is intermediate. Reproduction is ovoviviparous. The eggs develop inside the female and hatch internally. The young are born alive. They are miniature versions of the adults. This reproductive strategy is common in deep-sea sharks. The cold, dark environment makes external egg development risky. The protection is internal. The investment is high. The survival rate is improved. The method is specific. Not targeted by commercial fisheries, it is occasionally caught as bycatch in deep-sea trawls and longlines. It is not a valuable catch. Most are returned to the water. Survival is uncertain. The capture is accidental. The release is standard. The outcome is unknown. The impact is incidental. The value is negligible. To see one is rare. They live in the deep. In the cold, dark waters of the continental slope. They glow in the darkness. A soft green light hides them from below. They are the ghosts of the deep. Invisible until you are close enough to see the glow. The encounter is fleeting. The memory is vivid. The existence is verified. No one told it otherwise.