Jellyfish Facts ~ Jellyfish FAQ

by Orma Editors

in Jellyfish, Sea Life

What is the neatest fact about jellyfish?
They have been around for 700 million years which makes them the oldest multi-organ animal on the planet. They were around before dinosaurs. In contrast, recognizable humans have been around for about 2.2 million years and about 250,000 years for Homo sapiens.

What do jellyfish eat?
They are carnivores. Their diet includes other jellyfish, shrimp, fish and zooplankton.

Do jellyfish have brains or hearts?
They have no heart, no brain and function with a loose network of nerves located in their thin outer skin.

What are jellyfish made of?
They are composed of three layers: an outer layer, called the epidermis; a middle layer made of a thick, elastic, jelly-like substance called mesoglea; and an inner layer, called the gastrodermis. An elementary nervous system, or nerve net, allows jellyfish to smell, detect light, and respond to other stimuli. The simple digestive cavity of a jellyfish acts as both its stomach and intestine, with one opening for both the mouth and the anus.

JellyfishHow many species of jellys are there?
There are more than 200 different species of jellyfish inhabiting the oceans. There are even freshwater jellyfish as well.

What ocean animal kills the most people  each year?
The box jellyfish is the most dangerous marine animal in the world. Sharks kill far fewer people than box jellyfish (seawasps) do.

Can jellyfish be kept as pets?
Up until recently, it’s been extremely difficult to set-up and maintain a jellyfish aquarium and keep the jellyfish alive. Now for about $500 you can buy a jellyfish tank along with a moon jellyfish and have reasonable expectations that your moon jelly will live for about a year.

Pet Jellyfish Book

Pet Jellyfish Book

What is the largest jellyfish in the world?
Lion’s mane jellyfish’s bell can reach a width of 7ft  while its tentacles can be up to a 100 feet in length which makes them the biggest jellyfish by far.

Largest Jellyfish in the World- Lion's Mane Jellyfish

Largest Jellyfish in the World- Lion’s Mane Jellyfish

What is the smallest jellyfish in the world?
Irukandji are the smallest jellyfish in the world. They live in Australia and have venom that is very powerful; 100 times as potent as that of a cobra and 1,000 times as potent as that of a tarantula.

Smallest Jellyfish in the World

Smallest Jellyfish in the World- Tiny but Deadly

How is global warming affecting jellyfish?
Conventional wisdom states that global warming is spiking jellyfish populations but a recent study disputes that finding:
According to a BioScience statement, the study suggests that “the perception of an increase is the result of more scientific attention being paid to phenomena such as jellyfish blooms and media fascination with the topic.”
Condon, et al., note that the data doesn’t support such a conclusion:

“Clearly, there are areas where jellyfish have increased — the situation with the Giant Jellyfish in Japan is a classic example,” said Condon. “But there are also areas where jellyfish have decreased, or fluctuate.”

Do jellyfish have heads?
Not in the sense of holding a brain, but the closest thing to a head would be their bell.

What is the fastest jellyfish?
No particular species of jellyfish stand outs as being particularly faster than others.

How long do jellyfish live for?
2-6 months is the average. Longer in aquariums.

Are there freshwater jellyfish?
Yes, 1 species: Craspedacusta sowerbii

Do people eat jellyfish?
Yes, in Asian countries it’s quite popular. They tend to eat the tentacles after soaking them for a few days in water and then a quick parboil. Apparently they taste like seaweed with a crunch 

Cooked Jellyfish

Cooked Jellyfish- Yummy!

The best jellyfish sting relief?
Use sand to rub the stingers off, then vinegar to neutralize the venom.

What is the most poisonous jellyfish?
The box jellyfish aka sea wasp is the most poisonous jellyfish and deadliest sea creature in the world.

Beware of Box Jellyfish

This Sign is Probably in Australia

What is the life-cycle of a jellyfish?
This image from Wikipedia explains it best:

Jellyfish Life Cycle

Jellyfish Life Cycle

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{ 1 comment… read it below or add one }

Dave Marks May 24, 2013 at 2:28 pm

someone told me that if you see jelly fish are killing the oceans, is this true ?


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