The Lion’s Mane Jellyfish is a remarkable marine creature known for its impressive presence in the ocean. Its size and flowing appearance contribute to its imposing nature. These animals are some of the largest invertebrates found in marine environments, captivating observers with their unique characteristics.
Unpacking Their Gigantic Size
Lion’s Mane Jellyfish are among the largest jellyfish species globally. The bell, or top part of the jellyfish, can reach impressive diameters often ranging from 1 to 2 feet (30-61 cm) for typical individuals. However, specimens found in colder Arctic waters can have bells up to 7 feet (2 meters) across. Their tentacles can extend to extraordinary lengths.
The longest recorded Lion’s Mane Jellyfish was discovered off the coast of Massachusetts in 1865 or 1870. This specimen had a bell diameter of 7 feet (210 cm) and tentacles stretching an astonishing 120 feet (36.6 meters). To put this into perspective, this length is longer than a blue whale and about the height of a 10-story building. While such extreme sizes are rare, even average individuals are considerably large.
Distinctive Features Beyond Scale
Beyond their size, Lion’s Mane Jellyfish possess distinctive visual characteristics. Their bell is typically broad, flattened, and has a scalloped margin divided into eight lobes, resembling an eight-point star. The color of the bell varies from milky or pale pink in younger individuals to brick red, reddish-purple, or yellowish-brown as they mature. Larger specimens display deeper red or brownish-red hues.
Tentacles hang from the bell’s underside, inspiring their common name. These tentacles are arranged in eight clusters, with each cluster containing between 70 to 150 individual tentacles. These tentacles are equipped with stinging cells called nematocysts. Broad, frilly oral arms, also covered in these cells, extend from the central mouth on the bell’s underside.
Life Cycle and Environment
The Lion’s Mane Jellyfish’s size is supported by its life cycle and environmental resources. Their life cycle involves several stages, beginning as larvae that develop into polyps attached to the seabed. These polyps then reproduce asexually, creating stacks of ephyrae. Each ephyra eventually breaks away and matures into the bell-shaped medusa stage. This process from larva to mature adult takes about one year.
These jellyfish are predators, consuming prey to fuel their rapid growth. Their diet consists of zooplankton, small fish, crustaceans, and even other jellyfish. Lion’s Mane Jellyfish primarily inhabit cold, northern waters of the Arctic, North Atlantic, and North Pacific Oceans, ranging from Alaska to Washington. Cooler temperatures and abundant food in these regions contribute to their large size.
Encountering These Giants
Encountering a Lion’s Mane Jellyfish is notable due to their size. While their sting is painful and irritating, it is rarely fatal to humans. The tentacles contain nematocysts, which inject venom upon contact, causing symptoms like burning, itching, and redness. If stung, it is important to exit the water and carefully remove any remaining tentacles using tweezers or a gloved hand, avoiding direct contact.
Rinsing the affected area with hot water can alleviate pain and neutralize the venom. Some research suggests vinegar may also be beneficial for stings. These jellyfish are generally not aggressive; stings occur through accidental contact, especially in coastal waters during late summer and autumn. Avoiding direct interaction is the most effective way to prevent a sting.