Yes, that's correct! The mesopelagic zone, also known as the twilight zone, extends from about 200 meters (656 feet) to around 1,000 meters (3,280 feet) below the ocean's surface. It is characterized by limited light penetration, which decreases with depth, making it difficult for photosynthesis to occur.
In this zone, many species have adapted to the low-light environment by evolving bioluminescence, allowing them to communicate, attract prey, or evade predators. Bioluminescence is particularly useful for organisms that rely on the organic matter, or "marine snow," that sinks down from the upper epipelagic zone (the sunlit layer where most oceanic photosynthesis occurs). This dead organic matter and other debris serve as a primary food source for many mesopelagic creatures, including various small fish, squid, and zooplankton.
The mesopelagic zone is home to a diverse range of organisms, and it plays a crucial role in the ocean's carbon cycle, contributing to the biological pump that helps sequester carbon from the surface to deeper waters. Overall, the mesopelagic zone is a vital yet often overlooked part of the ocean ecosystem.