American Oceans

Length of Lion’s Mane Jellyfish vs Blue Whale

The Blue Whale is known for being the largest animal in the world. Saying this, it is not always the longest.

blue whale full length under the ocean

The Lion’s Mane Jellyfish rivals the Blue Whale in terms of length. So how long are Lion’s Mane Jellyfish compared to the Blue Whale?

Blue Whale Length

The Blue Whale is the largest animal in the world. The longest recorded length of a blue whale is 29.9 meters, or 100 feet. They have also reached weights up to 190 tons!

blue whale swimming by boat

The Blue Whale is not just the largest animal in the world, but the largest animal known to have ever existed! Scientists believe that Blue Whales have existed in the oceans for over 4.5 million years.

These whales tend to live up to 90 years old, and it usually takes them about 18 months to reach their full length – one of the fastest growth records of all animals! Even so, these whales continue to grow heavier as they become older.

Lion’s Mane Jellyfish Length

The Lion’s Mane Jellyfish is nicknamed the Giant jellyfish, and for good reason! It is the largest known jellyfish and has a recorded length of 36.6 meters (120 feet). This means that the Lion’s Mane Jellyfish tops the Blue Whale in terms of length!

lion's mane jellyfish with long tentacels

This jellyfish has been around significantly longer than the great blue whale, having existed 650 million years ago. Saying this, the Lion’s Mane has a lifespan of only twelve months.

Even so, 120 feet is a lot to grow into in just twelve months! Because of this, the Lion’s Mane Jellyfish also beats out the Blue Whale in terms of growth rate.

What’s Longer: Lion’s Mane Jellyfish or the Blue Whale?

The winner of the length contest between the Blue Whale and the Lion’s Mane Jellyfish is… the Lion’s Mane Jellyfish! The ability to reach lengths of 120 feet in 12 months is quite impressive!

Saying this, the Blue Whale wins in other aspects. While the jellyfish is longer, the whale has a heart, lungs, and a brain. Jellyfish only have a mouth, digestive system, and some pretty cool arms! Whales also live 90 times longer than their length-rival.


    • Not exactly. The one largest Lion’s Mane Jellyfish was 120 feet long, so it specifically was the longest animal in the world, but for the most part the Blue Whale still takes the cake. The Blue Whale “can grow up to about 90 feet ” “but in the Antarctic, they can reach up to about 110 feet” ( while “The length of a lion’s mane jellyfish’s tentacles can vary between 30 to 120 feet” ( Also, being 95% water, the Lion’s Mane Jellyfish “can weigh up to 200 pounds.” ( and the Blue Whale “weigh on average 200,000 to 300,000 pounds.” ( so the Blue Whale is still the largest animal in the world. However, as the article said, being able to grow 120 feet in 12 months is very impressive. For comparison, at peak growth humans grow an average of about 3.7 inches per year ( so as a zooplankton ( that’s pretty impressive.

    • Update. According to “in 1864, a bootlace worm (Lineus longissimus) was found washed up on the coast of Fife, Great Britain, that was 55 m (180 feet) long. (This claim is disputed because bootlace worms can easily stretch to several times their natural length, it is possible the worm did not actually grow to be that length.)” meaning that specimen may have not been the longest animal in the world.