Wildlife of the Week!

©Five Star Whale Watching. A Lion’s Mane Jellyfish is spotted towards the surface of the Salish Sea (circa 2010).

We have discussed a variety of amazing true jellyfish and other jellies in our “Wildlife of the Week” series, and today we will highlight another! The lion’s mane jellyfish (Cyanea capillata) is the largest jellyfish in the world, with its long tentacles capable of reaching extreme lengths. This jellyfish can sting, so as always, it is important to respect animals and not touch them in their habitats (even if a jellyfish is washed onto the beach). Did you know that despite this animal’s size, it is still considered a plankton? Read on below to learn why!

This jellyfish, as mentioned, is a species capable of reaching impressive lengths. Its tentacles may stretch to 120 feet long! As with other jellyfish, the main body (“bell”), is a round circular shape with under-hanging tentacles. This bell is usually a dark yellow, crimson, brown or red, but may be violet, tan, rose or white in appearance. It can also be up to ten feet wide. Water in the body included, this species can reach 200 pounds. Equipped with bioluminescence, this jellyfish can even create its own light in darkness. The name of the animal comes from its dense network of hanging tentacles, eight pairs of up to 150 tentacles each! This thick network creates the appearance of a mane. This jellyfish may also be called other names, like the giant jellyfish or the arctic red jellyfish. 

Hanging from the bell are the tentacles as mentioned, but oral arms can also be observed. These may look like a thicker and wider version of the tentacles. The tentacles, as with other true Cnidarians (jellyfish and anemones), are filled with tiny stinging needles that release poison. This sting can be harmful and painful to humans; it is used to kill the jellyfish’s prey. Do not touch a jellyfish or anemone in the water, or on the beach (it can still sting when washed up and/or dead). 

The lion’s mane jellyfish is an open-ocean (pelagic) creature, meaning it dwells within the water column. It is also usually floating towards the surface. The jellyfish can move, but like other jellyfish, cannot swim against a current and is always somewhat carried by the ocean waves. This is what places jellyfish into the “plankton” distinction. This species can be found in Arctic regions, as well as on the West Coast from Alaska to Washington. The jellyfish is also found in northern regions of the Atlantic Ocean, such as the North and Irish Seas and areas around Scandinavia. They prefer cold or cool waters, and do not thrive in warm temperatures. They have been spotted in other regions outside of the above, but these are less frequent habitats. 

The lion’s mane jellyfish forages for its food throughout the sea. The stinging tentacles of the jellyfish allow it to capture small fish, crustaceans, other jellies and other invertebrates. The mouth for the animal is actually located on the underside of the round bell. The oral arms of the jellyfish also assist with feeding and delivering food to the mouth. The glowing bioluminescence of the jellyfish can also help to attract prey. 

The lion’s mane jellyfish reproduces within the water column externally during the spring. Both males and females release genetic material that form a larva. The jellyfish will enter three more developmental stages throughout its life. In the second stage, the polyp stage, the jellyfish will reproduce asexually (think budding, small clones). The last stage is known as the “medusa” stage and is the adult form; it takes close to, or slightly over a month to reach this form. 

The lion’s mane jellyfish is most often spotted solitary, but they can be found in clusters together during storms. This jellyfish is an efficient swimmer when moving with the currents. Sea turtles enjoy feeding on lion’s mane jellyfish, and will travel to northern waters for specifically this reason. Seabirds and sunfish are also known predators. Juveniles are usually at greater risk for predation than larger adults. Despite the massive growth possibilities of this jellyfish species, they live only one year. 

Climate change and excessive human impacts on the ecosystem cause significant issues for many species. However, this is not the case for some select species. Interestingly enough, the lion’s mane jellyfish does well in areas with heavy human impact. This is due to the fact that negative impacts induced impact other species, reducing competition and predation. It is important to note the wide and drastic implications of habitat disruption and destruction, rather than select species doing favorably. 

The lion’s mane jellyfish is surely an amazing invertebrate! To learn more about this jellyfish, try some trivia below! 

  1. Why are jellyfish invertebrates? (ANS: They do not have a backbone). 
  2. True or False? Does this jellyfish, and other jellyfish, have a heart or brain? (ANS: No). 
  3. What are the stinging tentacles called? (ANS: Nematocysts). 


What scientific Class does this jellyfish belong to? 

Class Scyphozoa (true jellyfish). 

Article Authored By: Alexa D., B.Sc./ Five Star Whale Watching. 

To learn more about this jellyfish, visit our References below!

American Oceans.

Oceana Canada.