What Do Lanternfish Eat? Their Diet & Feeding Habits

Lanternfish, belonging to the Myctophidae family, represent one of the ocean’s most abundant vertebrate groups. These small, bioluminescent fish are found in every ocean basin worldwide, from tropical to polar waters. Despite their modest size, typically under 15 centimeters, their collective biomass is substantial, making them a significant, yet often unseen, component of deep-sea ecosystems globally. They play a widespread role in oceanic environments.

The Primary Diet of Lanternfish

The diet of lanternfish primarily consists of various zooplankton, which are small marine animals drifting in the water column. These include abundant crustaceans like copepods, euphausiids (commonly known as krill), ostracods, and amphipods. Copepods are a significant food source, especially for smaller lanternfish species, forming a fundamental link in their feeding habits.

As lanternfish grow larger, their diet often expands to include a wider range of prey. This can involve a shift from smaller copepods to larger euphausiids and other small crustaceans. Some larger lanternfish species also consume fish larvae or the larvae of other marine organisms. Occasionally, smaller squid larvae may also become part of their diet.

The specific composition of a lanternfish’s diet can vary significantly depending on several factors. These include the particular lanternfish species, its size, the geographic location it inhabits, and the seasonal availability of different prey items. For example, lanternfish in the Southern Ocean consume substantial amounts of Antarctic krill.

How Lanternfish Find and Capture Food

Lanternfish possess specialized adaptations enabling them to locate and capture food in the dimly lit deep ocean. Their large, often upward-facing eyes are highly sensitive, designed to maximize light collection in the mesopelagic zone. These eyes are adept at detecting faint ambient light filtering from the surface and the bioluminescent flashes emitted by other organisms, including potential prey.

A prominent adaptation is their bioluminescence, produced by light-emitting organs called photophores. These photophores are arranged in species-specific patterns along their belly and sides. While primarily used for counter-illumination, matching the faint downwelling light to camouflage their silhouette from predators below, some species may also use flashes to illuminate or even attract small prey.

The light produced by photophores also serves as a communication tool, with unique flashing patterns used for species recognition and courtship. Once prey is detected, lanternfish utilize their large, terminal mouths, which are equipped with rows of small, sharp teeth. This mouth structure is well-suited for grasping and holding the small, often slippery zooplankton and other invertebrates that constitute their diet.

Habitat and Feeding Habits

Lanternfish primarily inhabit the mesopelagic zone, often referred to as the ocean’s twilight zone, typically residing at depths between 200 and 1,000 meters during daylight hours. This environment is characterized by limited sunlight and scarcer food resources compared to surface waters. Their feeding strategies are intrinsically linked to this deep-sea habitat.

A key aspect of their feeding behavior is diurnal vertical migration (DVM), recognized as the largest daily animal migration on Earth by biomass. As dusk approaches, most lanternfish species ascend from their deep daytime refuge to the shallower, food-rich epipelagic zone, typically ranging from 10 to 100 meters deep. This nightly ascent allows them to feed on the abundant zooplankton that also migrate upwards.

By dawn, they descend back to the deeper, darker mesopelagic zone. This migration serves a dual purpose: it provides access to plentiful food sources at night and offers refuge from visual predators that hunt in well-lit surface waters during the day. While this is a common pattern, not all lanternfish species undertake this daily migration, with some remaining at depth.

The specific timing and depth of these migrations can vary based on factors such as the particular species, its life stage, and geographic location. This daily commute ensures lanternfish efficiently acquire the necessary energy while minimizing their exposure to predators in the extensive marine environment.

Lanternfish in the Marine Food Web

Lanternfish occupy a central position in the marine food web, serving as a crucial link that transfers energy from lower to higher trophic levels. By consuming abundant zooplankton in surface waters, they effectively convert microscopic life into a food source accessible to a wide array of larger marine predators.

Their immense collective biomass makes them a significant food source for many oceanic animals. This includes large pelagic fish such as tuna, salmon, and various shark species, which actively prey on lanternfish. Marine mammals like whales, dolphins, and seals also rely on lanternfish to meet their substantial energy needs.

Furthermore, cephalopods, including various squid species, and numerous seabirds, notably penguins, regularly feed on lanternfish. Through their daily vertical migrations, lanternfish also play a role in the biological carbon pump, transporting organic matter and carbon consumed near the surface to the deep sea when they descend, thus contributing to nutrient cycling within the ocean.