Ocean of Hope

10 Lion’s Mane Jellyfish Facts: the Biggest Jellyfish

Lion's Mane Jellyfish facts
Lion's Mane Jellyfish photo by: NOAA

10 Lion’s Mane Jellyfish Facts: the Biggest Jellyfish

1. The Lion’s Mane Jellyfish is the biggest Jellyfish in the world. Its bell can reach up to 8 feet in diameter, and its tentacles up to 120 feet long (that’s longer than a blue whale!).

2. The Lion’s Mane Jelly lives in the North Atlantic, North Pacific, and Arctic Oceans.

3. The Lion’s Mane Jelly is bioluminescent (glows in the dark!).

4. Like all jellies, the Lion’s Mane Jelly has no brain, blood, or nervous system.

5. Like all jellies, the Lion’s Mane Jelly is 95% water.

6. There are 200 species of True Jellies.

7. All Jellies are radially symmetrical.

8. Jellies have no eyes, but rather eye spots that detect light and dark.

9. Lion’s Mane Jellies have nematocysts in their tentacles that they use to sting their prey. Nematocysts are barbs (sharp points) filled with venom.

10. A Jelly can sting you even if washed up on the beach so be careful! Jelly stings on humans can be treated with vinegar to lessen the pain.

Also see: 10 Jellyfish Facts for Kids
Why Jellyfish may become the “Cockroaches of the Sea”
Lion’s Mane Jellyfish from Oceana

10 Jellyfish Facts for Kids

Jellyfish facts largest & smallest
Lion's Mane Jellyfish: the largest jelly in the ocean

10 Jellyfish Facts for Kids

1. A jellyfish is not a fish at all, it is an
invertebrate (animal without a backbone).

2. Invertebrates make up 95% of all animals on earth.

3. A jelly is made up of approximately 95% water.

4. A jelly does not have a brain, eyes, bones, teeth, or blood.

5. A jelly reproduces by making clones of itself (exact copies of itself) so it technically never dies.

6. There are 2 main stages to a jelly’s life cycle, the sessile (stuck to a surface) polyp, and the free-swimming medusa (what you think of as a jelly).

7. The largest jelly ever found was a Lion’s Mane Jelly with a diameter of 7 feet 6 inches (2.29m) and its tentacles trailed 120 feet behind it!

8. The smallest jelly is the Irukandji jelly which is only 1 1/2 inches in diameter.

9. Jellies are found in all the world’s oceans.

And the last jellyfish fact for kids is:

10. A box jelly (sea wasp) sting can kill you within 2-3 minutes.

10 Facts About the Lion’s Mane Jellyfish
10 Jellyfish Facts for Kids and Jelly Enthusiasts

Why Jellyfish May Become the “Cockroaches of the Sea”

jellyfish as cockroaches of the sea
Sea Nettle Jellies photo by Cherilyn Jose

While jellyfish (referred to as jellies for rest of this post since they are not “fish”) have been painted by public aquariums to be moving and floating masterpieces, the ocean itself has a different viewpoint on them. If the oceans keep getting polluted and overfished at their current rate, the ocean may soon teem with jellies and little else.

Pollution can be in the form of chemicals, like fertilizers and treated (or untreated in many parts of the world) sewage. Pollution can also be physical, like garbage. Plastic is particularly common, and all sorts of wildlife ingest it. The most well publicized plastic eaters include sea turtles who mistake not only plastic bags for jellies, but any plastic bits floating in the sea, and sea birds who have been found dead with enough plastic in their stomachs to die from starvation. With those predators dead, jellies take advantage of the increasing amount of plankton and they proliferate like crazy.

Plankton are the bottom layer of the food web. Overfishing takes out of the ocean the edible sized fish that eat plankton and other small bait fish. With their predator fish gone, plankton proliferate. Jellies love plankton, and they can easily outcompete any young fish for it. The young fish die without reproducing and therefore do not replace their parent’s generation. The seas would theoretically become empty of anything but jellies.

Off of Japan there has been a lot of overfishing, and Nomura’s jellyfish are increasing at an astonishing rate. They can grow to be 6.5 feet (2 meters) wide and weigh up to 450 pounds (220 kg)! Fishermen pull up nets with nothing but hundreds of jellyfish in them. Many nets break under the jellies massive collective weight, and one boat even capsized from them! The fishermen’s early strategy to get rid of them by slicing them up actually increased the jelly population due to the special asexual reproductive techniques of jellies. A future post will delve into this unique aspect of jellies.

Not all news relating to jellies is bad, as their tentacles have inspired scientists create a cancer detector. Scientists made a long DNA strand that mimics the sticky nature of jelly tentacles. In experiments, this long DNA strand was able to capture 80 percent of the leukemia cells (a kind cancer cell) in the blood used. For more on this, please visit “Jellyfish Inspire Cancer Detector” at the Huffington Post.

Please note that I was unable to write this post from the point-of-view of a jelly, as they do not have brains!