World's Biggest Glowing Vertebrate May Be Using Its Own Light as a Hunting Tool

Key Points:

• The kitefin shark, the world's largest glowing vertebrate with no known predators, uses bioluminescence not only for camouflage through counterillumination but also potentially as a biological searchlight to locate prey.
• Researchers found that the shark's glow matches the ambient light in color and brightness for concealment from below, but uniquely emits light laterally, especially around its nose and fins, which may illuminate the seafloor to spot prey.
• Unlike typical counterillumination, the kitefin's dorsal fin glows dimly but noticeably, suggesting functions beyond camouflage such as intraspecific signaling or attracting prey.
• This dual use of bioluminescence challenges the conventional view that counterillumination solely serves to avoid predators, indicating the shark may simultaneously hide from threats and actively hunt using its light.
• While the findings are based on physical measurements of captured sharks, confirming these behaviors requires further observation of kitefin sharks in their natural deep-sea environment.