Lampridae
The Lampridae, commonly known as opah, moonfish, or kingfish, is a family of ray-finned fish in the order Lampriformes. These fish are found in temperate and tropical waters worldwide, inhabiting the mesopelagic zone of the ocean, between 200 and 1,000 meters deep. They are characterized by their distinctive, deep, laterally compressed bodies, with an elongated, dorsal fin extending the length of their backs, and their striking coloration, often featuring a bright, iridescent silver or gold sheen. While once thought to be rare, recent research suggests that opah are more common than previously believed.
Characteristics
Lampridae possess several unique characteristics that set them apart from other fish. Notably, they have a heart that is considerably larger in proportion to their body size compared to other fish species. This allows them to maintain a high metabolic rate even in the cold, oxygen-poor depths where they live. Additionally, they possess a highly vascularized network of blood vessels in their gills, which aids in the efficient uptake of oxygen from the surrounding water.
These fish are also known for their unusual swimming habits. They are one of the few fish species that have the ability to maintain a constant internal body temperature higher than the surrounding water, a characteristic known as regional endothermy. This allows them to be more active and efficient hunters in the cold depths.
Environment
Opah inhabit the mesopelagic zone of the ocean, a region characterized by low light levels, cold temperatures, and limited food availability. They are thought to be primarily active predators, feeding on squid, jellyfish, and other fish. The presence of numerous small teeth and sharp, curved spines along their gill arches supports this feeding strategy. They are also known to occasionally feed on plankton.
Distribution
Lampridae are found in temperate and tropical waters around the globe. They have been observed in the Atlantic, Pacific, and Indian Oceans, as well as the Mediterranean Sea. They are known to occur at depths ranging from 200 to 1,000 meters, but they can occasionally be found at shallower depths. They are most commonly observed in waters with a temperature range of 8 to 12°C (46 to 54°F).
Conservation Status
The conservation status of Lampridae is currently assessed as Least Concern by the International Union for Conservation of Nature (IUCN). This assessment is based on their relatively wide distribution and their resilience to fishing pressure, as they are not a commercially targeted species. However, due to their slow growth rate and late maturity, they are susceptible to overfishing if their populations are subjected to intense fishing pressure.