Lion's Mane Jellyfish - Oceana

Corals and Other Invertebrates

Lion’s Mane Jellyfish

Cyanea capillata


Cooler regions of Pacific, Atlantic and North Sea region


Pelagic (Open Ocean)

Feeding Habits

Foraging Predator


Class Scyphozoa (true jellies), Family Cyaneidae


The lion’s mane jellyfish cannot be missed in the open ocean where it prefers to float about. With tentacles up to 120 feet long, some individuals even rival in size the blue whale, the largest animal in the world. Most lion’s mane jellyfish live in the Arctic and North Pacific Ocean from Alaska to Washington where the waters are cool. Its ‘mane’ of long, hair-like tentacles hanging from the underside of its bell-shaped body is the inspiration behind the lion mane’s common name. The mouth is situated on the bell’s underside, surrounded by tentacles that are divided into eight clusters of up to 150 tentacles each. These tentacles are equipped with nematocysts containing poison that stun prey when they are enveloped. The top of the bell is usually dark yellow or red in color and thick in the center, but thins out towards the edges. The lion’s mane jellyfish also possess bioluminescent abilities, meaning it’s able to produce its own light and glow in the dark underwater.

Using the powerful sting of its tentacles, the lion’s mane jellyfish catches small fishes, tiny crustaceans and even other jellyfish to satisfy its diet. Lion’s mane jellyfish are continual swimmers that can cover great distances when strong marine currents are present, and while most individuals prefer to swim solo, large swarms occasionally occur when storms and tides are prevalent. The lion’s mane jellyfish breeds in March and early May via external fertilization. Larvae will settle on the seabed and develop into polyps that eventually grow into jellyfish within 30-40 days.

Scientific research has suggested that jellyfish actually thrive in areas that are affected by human activity. Overfishing, climate change and pollution have helped promote more frequent jellyfish swarms while reducing the jellies’ main predators and competitors and increasing their prey. These factors have created a favorable environment for this species, and few threats are known to the lion’s main jellyfish or other jellies.

Fun Facts About Lion’s Mane Jellyfish

1. The lion’s mane jellyfish is one of the largest jelly species in the world, growing to an average length of 1.5 feet (40 cm), but can reach lengths of 6.5 feet (200 cm).

2. The lion’s mane jellyfish is named after its “mane” of long, hair-like tentacles hanging from its bell.

3. A lion’s mane jellyfish has up to 1,200 tentacles divided into eight clusters.

4. Lion’s mane jellyfish hunt by extending their tentacles outward and creating a trap that captures prey like fish and crustaceans.1

5. The largest lion’s many jellyfish ever recorded was 120 feet (36.5 m) long.

6. The lion’s mane jellyfish delivers a powerful sting that can be very painful to humans.2

Engage Youth with Sailors for the Sea

Oceana joined forces with Sailors for the Sea, an ocean conservation organization dedicated to educating and engaging the world’s boating community. Sailors for the Sea developed the KELP (Kids Environmental Lesson Plans) program to create the next generation of ocean stewards. Click here or below to download hands-on marine science activities for kids.

Kids Environmental Lesson Plans


1 The Marine Life Information Network

2 University of Gothenburg