The megamouth shark is an enigmatic creature of the deep ocean. Its existence was unknown to science until relatively recently, sparking fascination. This large filter-feeding shark, with its unique appearance and elusive nature, continues to intrigue those curious about life beneath the waves.
Are Megamouth Sharks Still Alive?
Despite rare sightings, the megamouth shark is not extinct; it is still alive. The misconception about its existence arises because it is one of the rarest and most infrequently encountered shark species in the world. Since its discovery in 1976, fewer than 300 confirmed sightings have been recorded globally. These sharks primarily inhabit deep-sea environments, which are challenging for humans to access and observe, contributing to their mysterious reputation.
Discovery and Unique Features
The megamouth shark’s scientific discovery was a significant event in marine biology due to its unexpected nature. The first specimen was accidentally captured on November 15, 1976, near Kaneohe, Hawaii, when it became entangled in the sea anchor of a United States Navy research vessel. This initial encounter revealed a species so distinct that it was classified into its own family, Megachasmidae, and genus, Megachasma, with the scientific name Megachasma pelagios. The name “megamouth” aptly describes its most striking characteristic: an unusually large, broad mouth that can extend up to 1.3 meters (4.27 feet) wide on a 5-meter shark.
This shark possesses a stout body, a bulbous head, and rubbery lips, giving it a distinctive appearance. Unlike most sharks, the megamouth is a filter feeder, similar to whale sharks and basking sharks. It swims with its mouth open, filtering zooplankton, such as krill, copepods, and jellyfish, from the water using specialized finger-like gill rakers. While early theories suggested its white upper lip might be bioluminescent to attract prey, more recent studies have found no light-producing organs; instead, the white band on its jaw likely reflects light from bioluminescent prey or ambient light.
Where Megamouth Sharks Live
Megamouth sharks inhabit a wide geographical range across the Pacific, Atlantic, and Indian Oceans, typically found within tropical and temperate latitudes between 40° N and 40° S. Despite this broad distribution, sightings are scattered and infrequent. These sharks prefer deep-water environments, specifically the mesopelagic (twilight) and bathypelagic (midnight) zones, descending to depths of up to 1,500 meters (about 4,920 feet).
They exhibit a behavior known as diel vertical migration, spending daylight hours in deeper waters, often between 120 and 160 meters (390-520 feet), and ascending to shallower depths, between 12 and 25 meters (39-82 feet), at night. This vertical movement is synchronized with the migration of their primary food source, zooplankton, which also move closer to the surface during nighttime. While primarily a deep-ocean dweller, megamouth sharks have occasionally been observed or caught near coastal areas, often as incidental bycatch.
Understanding Their Rarity and Protection
The rarity of megamouth shark sightings is primarily attributed to their deep-sea habitat and potentially low population density. The International Union for Conservation of Nature (IUCN) currently classifies the megamouth shark (Megachasma pelagios) as a species of “Least Concern.” This classification reflects the absence of widespread known threats or significant population declines, rather than a confirmed robust population size.
Little data exists on their exact population numbers or distribution, making comprehensive conservation assessments challenging. The primary known threat is incidental bycatch, where they are unintentionally caught in fishing nets, particularly in driftnet fisheries targeting other species like sharptail mola. Although these instances are relatively rare, the species’ slow reproduction rates mean that any population impacts are hard to quantify and reverse. Research into their behavior, migration patterns, and overall population health is ongoing to better understand and protect this deep-sea inhabitant.