The Lion’s Mane Jellyfish (Cyanea capillata) is the largest known jellyfish species in the world. Individuals in colder northern waters can reach a bell diameter of up to eight feet and have tentacles stretching over 100 feet long. This formidable marine predator is a carnivore that drifts through the water column. It relies on its massive, trailing tentacles to ensnare and subdue its food, illustrating its substantial ecological influence.
Primary Prey of the Lion’s Mane Jellyfish
The diet of the Lion’s Mane Jellyfish is highly varied, reflecting its opportunistic nature. Young and small individuals primarily feed on microscopic zooplankton, such as copepods, rotifers, and tiny larval crustaceans. As the jellyfish grows, its diet shifts to larger prey items that provide more energy for its increasing body mass. The adult diet includes small fish, like larval fish and fry, which are paralyzed by the powerful sting. Adults also consume small crustaceans, including shrimp and krill, and other gelatinous organisms, such as Moon Jellies and smaller Lion’s Mane individuals.
How Lion’s Mane Jellyfish Capture Food
The Lion’s Mane Jellyfish employs a passive, “net-fishing” strategy, utilizing its vast array of tentacles as a massive, sticky trap. The underside of the bell is lined with eight clusters of tentacles, which can collectively number over 1,000 strands. These long filaments drift below the bell, creating a deadly curtain that unsuspecting organisms swim into. The tentacles are armed with specialized stinging cells called nematocysts, which discharge a neurotoxin upon contact to instantly stun or paralyze the victim. Specialized structures near the mouth, known as oral arms, then draw the immobilized food toward the central opening and into the digestive cavity.
The Lion’s Mane Jellyfish in the Food Web
The Lion’s Mane Jellyfish occupies a unique position in the marine food web, acting as both a major predator and a food source. By consuming zooplankton and small fish, it helps regulate populations at lower trophic levels within its ecosystem. Its presence also creates a localized shelter effect, as some small juvenile fish use the stinging tentacles as a barrier against larger predators. Despite its venomous defenses, the jellyfish is preyed upon by several larger marine animals. Predators include the Leatherback Sea Turtle, the Ocean Sunfish (Mola mola), certain seabirds, and large fin fish.