Lanternfish

Lanternfish are a large, diverse family (Myctophidae) of small mesopelagic fish found throughout the world's oceans, with hundreds of described species. Myctophum punctatum is a widely studied representative from the North Atlantic. Lanternfish get their name from rows of light-producing photophores along the body, which produce a soft glow used for communication and camouflage. Despite their small size, lanternfish are considered one of the most numerically abundant vertebrate groups on Earth and form a major link in deep-sea food webs, connecting plankton to larger predators. They undertake some of the largest daily migrations of any animal group, moving between deep daytime refuges and near-surface waters at night.

Lanternfish share a small, slender, silvery body plan with distinctive light organs.

• Rows of small, precisely arranged photophores along the belly, sides, and head
• Large eyes adapted to extremely low light conditions
• Silvery sides fading to darker coloration on the back
• Single soft dorsal fin and a small adipose fin near the tail
• Forked tail fin suited to short bursts of swimming

Species identification within Myctophidae often relies on the exact number and arrangement of photophores, which is highly consistent within each species and used by researchers to distinguish otherwise similar-looking lanternfish from one another and from unrelated deep-sea groups like hatchetfish.

Lanternfish are found throughout the world's oceans, from polar to tropical waters, generally inhabiting the mesopelagic zone at depths of roughly 200-1,000 meters during the day. They are famous for performing one of the largest synchronized migrations on the planet, rising toward the surface, often into the upper 200 meters, at night to feed before descending again at dawn. This diel vertical migration allows lanternfish to access food-rich surface waters while minimizing exposure to visual predators during daylight. Lanternfish inhabit open water throughout their lives, showing no attachment to bottom structure, and their sheer abundance makes them a dominant biomass component of the open ocean water column.

Lanternfish school loosely in the mesopelagic zone and are best known for their nightly vertical migration toward the surface to feed on zooplankton, followed by a return to deeper, darker water at dawn. Their photophores are used for counter-illumination camouflage, matching downwelling light from above to make the fish less visible to predators looking upward, as well as for species recognition and possibly schooling coordination. Lanternfish reproduce by releasing pelagic eggs into open water, and their larvae develop while drifting with ocean currents. As one of the most abundant fish groups on Earth, lanternfish form a critical link in deep-sea food webs, transferring energy from plankton to larger predators such as squid, tuna, and seabirds.