Critter Science

The Science of Animals


Diving into the World of Jellyfish

Jellyfish are fascinating critters. They have stinging tentacles that are used to immobilize their prey in order to feast. Jellyfish have no heart, no eyes and also… no brain–kind of like politicians. Lets take a closer look at these critters now…

First the Stats…

Scientific name: Medusozoa
Phylum: Cnidaria
Higher classification: Cnidaria
Rank: Subphylum
Lifespan: Lion’s mane jellyfish: 12 months | Chrysaora fuscescens: 6 months
Size: 0.039″ to over 6 ft. Bell size plus the length of the tentacles makes them even larger
Top speed: 8km/h (5 mph)
Diet: Fish, shrimp, crabs, tiny plants and even other species of jellyfish

Now on to the Facts!

1.) Jellies have no brains! Jellyfish instead have neural nets which sense changes in their environment and help coordinate the animal’s responses. They respond to water currents and other external stimuli and react accordingly.

2.) A group of high school students in Japan reportedly developed a salted caramel recipe that uses powered jellyfish. That’s one way to deal with the invasive jellyfish blooms.

3.) Did you know that jellyfish have the ability to clone themselves and even regenerate after being injured?

4.) Jellyfish are found throughout every ocean as well as some lakes!
5.) Many jellyfish have bioluminescent organs, which emit light.

But wait, there’s more about the jellyfish!

6.) The jellyfish’s mouth is found in the centre of its body. From this small opening it both eats and discards waste. And it serves another purpose, too – by squirting a jet of water from its mouth, the jellyfish can propel forward.

7.) Jellyfish stings can be very painful to humans and, from certain species (like the box jelly – Chironex fleckeri, Carukia barnesi and Malo kingi), they can even be deadly. Although these magnificent marine creatures don’t purposely attack humans, most stings occur when people accidentally touch a jellyfish’s tentacles.
8.) Jellyfish blooms have previously been responsible for shutting down several nuclear reactors, which often rely on ocean water intakes. The jellyfish swarms can clog the intake pipes, forcing facilities to stop operating temporarily.

Did you know…?
There are two phases to jelly life: the stationary polyp stage and the mobile medusa phase. It’s the medusa phase that we’re usually referring to when we talk about jellyfish.

9.) The Turritopsis nutricula jelly has earned it the nickname “Immortal Jellyfish” for having the ability to revert back to the polyp stage in times of stress.

But wait, there’s even more jellies!

box jellyfish
10.) The big box jellyfish is the most venomous on the planet! It is so venomous it will kill you within two to five minutes if you receive two meters (6 feet) or more of tentacle contact. Their stings contain toxins that attack the heart, nervous system, and skin cells. It is so overwhelmingly painful that human victims have been known to go into shock and drown or die of heart failure before even reaching shore. Survivors can experience considerable pain for weeks and often have significant scarring where the tentacles made contact.
turtle eating jellyfish
11.) Sea turtles and blue dragons will eat jellyfish and are immune to their stings.

12.) The Chinese have fished jellyfish for around 1,700 years. They are considered a delicacy and are used in Chinese medicine.

13.) Each jelly tentacle is armed with thousands of cells called cnidoblasts. Inside the cnidoblasts are nematocysts, each of which contains a coiled stinging thread. When a fish or other object becomes tangled in the tentacles, the pressure inside the nematocysts causes the venomous threads to uncoil like a spring-loaded harpoon.
14.) Jellies are invertebrates, which means they are animals without a skeleton. Approximately 95% of their body is water.

15.) Jellyfish range from the size of a thimble or the eraser tip of pencil to approximately eight feet in diameter with tentacles that reach 200 feet. That is as long as two blue whales.

Now a Short Video!

Critter Man

With over 40 years of critter experience to my credit and hundreds of zoology teaching hours to people around the world, I have amassed not only a continuing thirst for critter knowledge but a desire to teach others all I can about the majesty and wonder of our natural world. Critter Science is a culmination of such knowledge.I have hands on as well as book acquired intel on all kinds of critters. Whether they're on land, sea, or air.I will never say that I know everything about all animals. That's impossible, even for a savant. But, that being said, ask me any animal question and I'll answer it. If I don't know the answer, I'll get an answer for you!Let it be said that I have been oft times accused of loving animals more than I love people. I can neither confirm nor deny this.

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