Lion's Mane Jellyfish - Oceana Canada

Corals & Other Invertebrates

Lion’s Mane Jellyfish

Cyanea capillata


Lion’s mane, lion’s mane jelly, sun jellyfish, sea blubber


Colder ocean regions of the Northern Hemisphere


Pelagic (open ocean)


Foraging predator


Class Scyphozoa (true jellies); Family Cyaneidae


Lion’s mane jellyfish are the longest animal in the world! Their body and tentacles can grow up to 36.5 metres in length, rivaling blue whales which can grow up to 33 metres long. Lion’s mane jellyfish get their name from a ‘mane’ of long, thin, hair-like tentacles that hang from the underside of their bell-shaped body. These tentacles have cells called nematocysts that harbour a powerful sting used to burst and paralyze their prey, such as fish, crustaceans, and even other jellyfish.


Lion’s mane jellyfish are typically a light to deep orange or crimson colour, but can also be yellow, tan, rose, violet or even white. Their body is bell shaped and usually grows 30 to 50 centimetres in diameter, with the largest individuals growing to as much as 2.5 metres in diameter! They also have eight groups of 70 to 150 tentacles. Depending on the size of the individual, these tentacles can range from nine to just over 36 metres in length.



Lion’s mane jellyfish breed in March to early May via external fertilization. After fertilized eggs hatch, the larvae will settle on the seabed and develop into polyps. In the polyp stage they stay connected to the seafloor where they feed and grow, eventually growing into an adult jellyfish, called a medusa, within 30 to 40 days. Lion’s mane jellyfish typically hatch, grow, reproduce and die within about one year. The only known predator of lion’s mane jellies are sea turtles, most notably leatherback sea turtles, which travel to cooler waters of the northern hemisphere in the summer to gorge themselves on these jellyfish.



Lion’s mane jellyfish are not directly targeted by fisheries, and it is not well known if they are adversely impacted by fishing activities.



The status of lion’s mane jellyfish in Canadian waters is unknown. However, it is suggested that jellyfish thrive in areas affected by human activity. Overfishing, climate change and pollution have helped promote more frequent swarms of jellyfish while also reducing their main predators and competitors. These changes, like increased acidification of the ocean, have created a favourable environment for this species, and few threats are known to lion’s mane jellyfish other than predation from sea turtles.