The lion’s mane jellyfish, scientifically known as Cyanea capillata, is one of the largest known jellyfish species. Its name comes from the extensive, trailing mass of tentacles that resemble a lion’s mane. These marine creatures possess a bell that can reach an impressive diameter, sometimes exceeding two meters, and their tentacles can extend over 36 meters in length.
Global Distribution
Lion’s mane jellyfish are primarily found in the cold, boreal waters of the Northern Hemisphere. Their broad geographical range encompasses the Arctic, North Atlantic, and North Pacific Oceans. Specific habitats include the English Channel, Irish Sea, and North Sea, along with the western Scandinavian waters. They are also prevalent along the coasts of North America, including the Gulf of Alaska and the Bering Sea. While typically associated with northern latitudes, some populations have been observed as far south as the Gulf of Mexico, and similar jellyfish inhabit seas near Australia and New Zealand.
Environmental Preferences
These jellyfish thrive in cooler water temperatures, generally preferring conditions below 20°C (68°F). The largest specimens are typically encountered in the coldest, most northern parts of their range. They are pelagic organisms, inhabiting the open ocean, yet they tend to remain close to the surface, usually at depths no greater than 20 meters (65 feet). Their movement through the vast ocean is largely dependent on prevailing ocean currents, as their own pulsations provide only weak propulsion. They are active carnivores, preying on a variety of smaller marine life, including zooplankton, small fish, tiny crustaceans, and even other jellyfish.
Seasonal Presence
The appearance of lion’s mane jellyfish in coastal areas often follows a seasonal pattern, becoming more noticeable in late summer and autumn, when they have grown to a substantial size and ocean currents sweep them closer to shore. Their life cycle, which spans approximately one year, progresses through larval, polyp, ephyrae, and medusa stages. In regions like British waters, young individuals may be seen as early as February, with peak abundance of larger jellyfish from June to September. In the North Atlantic, the medusa stage appears in April or May, developing rapidly throughout the summer. Conversely, in the southeastern United States, their presence is observed during colder months, from late December or early January, peaking in late winter and early spring before vanishing by mid-May.