The Lion’s Mane Jellyfish is not only the largest jellyfish in the world (one specimen measured 120 feet [36.5 meters] – longer than the Blue Whale), it is also one of the more dangerous. Its body structure is similar to other jellyfish with a bell-shaped “body” that contains its digestive and reproductive organs above, and a thick mass of dangling tentacles below. These tentacles – which can number over one hundred on some specimens – are loaded with special stinging cells called nematocytes. These cells can deliver large doses of neurotoxins to other animals, which is the Lion’s Mane Jellyfish’s main form of defense. In humans, these stings can differ in severity from person to person. Healthy people may only encounter a painful rash, while others will have to enduring severe, painful blistering, muscle cramps, breathing problems and even death.
Fans of Sir Arthur Conan Doyle’s Sherlock Holmes stories may recognize this jellyfish from one of those famous mysteries. In “The Adventure of the Lion’s Mane,” this particular animal caused the death of a school professor who inadvertently swam with some offshore.
Like all jellies, the Lion’s Mane must rely on the ocean’s currents to find food and travel from place to place. They can often be spotted near shore and in the upper 65 feet (20 m) of water from Alaska to southern California.