The lion’s mane jellyfish, scientifically known as Cyanea capillata, is one of the largest jellyfish species globally. This marine invertebrate has a prominent bell-shaped body and numerous long, trailing tentacles. Its common name comes from the dense, flowing mass of tentacles that resemble a lion’s mane. The bell varies in color, ranging from lighter orange and tan in smaller individuals to deep crimson or reddish-brown in larger specimens.
Geographical Distribution
The lion’s mane jellyfish primarily inhabits the cold, boreal waters of the Northern Hemisphere. Its extensive range spans across the Arctic, North Atlantic, and North Pacific Oceans. This species is notably absent from tropical regions.
In the North Atlantic, populations are common in the English Channel, Irish Sea, North Sea, and western Scandinavian waters, extending south to Kattegat and Øresund. Along the coasts of North America, it is observed from eastern Canada down to the Pacific Northwest (Alaska to Washington), and also occurs in the northeast and northwest United States.
Across the North Pacific, the lion’s mane jellyfish is found off the coasts of Alaska, Japan, and Russia. Occasionally, individuals are sighted further south in areas like southern California, southern Florida, and even the Gulf of Mexico, although specimens found in these warmer waters tend to be smaller.
Preferred Aquatic Conditions
The lion’s mane jellyfish prefers cold ocean temperatures, thriving in marine environments where water temperatures typically range from 0 to 18 degrees Celsius (32 to 64 degrees Fahrenheit). It cannot tolerate warmer waters. This species is commonly found in surface or epipelagic waters, generally remaining within 20 meters (66 feet) of the ocean’s surface, though it can sometimes be found at greater depths.
Movement for the lion’s mane jellyfish largely relies on ocean currents, as its own slow pulsations only weakly propel it forward. This dependence allows them to cover significant distances. They are frequently observed during late summer and autumn, a period when currents tend to sweep them closer to shore.
The jellyfish requires high salinity levels for its habitat. This explains why, despite occasionally drifting into areas like the Baltic Sea, it cannot successfully reproduce there due to the lower salinity. While predominantly found in the open ocean, lion’s mane jellyfish can also inhabit coastal waters. Towards the end of their approximately one-year lifespan, they may move into sheltered, shallower bays to avoid strong ocean currents.