There are jellyfish in every ocean in the globe. Even some freshwater lakes and ponds contain them.¹⁾

Jellyfish have tentacles that can extend 200 feet and range in size from a thimble or the eraser tip of a pencil to around eight feet in diameter. That equates to two blue whales in length.²⁾

Thousands of cells known as cnidoblasts are embedded in each jellyfish tentacle. The nematocysts, which each contain a coiled stinging thread, are found inside the cnidoblasts.³⁾

The major defensive systems of the jellyfish are its stings and its translucent body, which makes it simple for it to conceal itself.⁴⁾

In a Friends episode, one of the characters treats a jellyfish sting with pee. Urine, according to neuroscientists, is ineffectual.⁵⁾

According to many neurosurgeons, common anti-sting therapies like vinegar, urine, and meat tenderizers are ineffective. The best course of action is to exit the water right away and wash the damaged area with salt water (NOT fresh water). The stinging cells will become inactive in salt water, but they will become active again in fresh or tap water. Utilizing a tool like a credit card is the most effective approach to remove the cells.⁶⁾

A jellyfish's body has a little tube that hangs downward. Its mouth and digestive tube are both contained within the tube.⁷⁾

There are no brains, hearts, ears, heads, feet, legs, or bones in jellyfish. ⁸⁾

They can breathe through their skin because it is so thin.⁹⁾

Although jellyfish lack a brain, they do have a basic neurological system that includes sensors for light, vibrations, and chemicals in the water.¹⁰⁾

The Jellyfish is able to navigate and orient itself in the water using gravity and its sense of weight.¹¹⁾

Invertebrates, or creatures without a skeleton, include jellyfish. Their body contains about 95% water.¹²⁾

Although jellyfish are often found in shallow coastal waters, several species have been found to exist at low depths.¹³⁾

Some jellyfish may survive in subarctic conditions, however most prefer warm water.¹⁴⁾

Even when detached from the jellyfish body, a tentacle can still sting.¹⁵⁾

The creeping jellyfish is the tiniest jellyfish in existence. It contains bell disks with diameters ranging from 0.5 mm to a few millimeters.¹⁶⁾

The very deadly Australian Irukandji jellyfish, which is just the size of a fingernail, is another contender for the title of tiniest jellyfish.¹⁷⁾

The Nomura's jellyfish is the biggest jellyfish in the world. The Lion's mane jellyfish and the Stygiomedusa gigantea are further contenders for the title of biggest jellyfish.¹⁸⁾

In the past 120 years, only around 100 times have the enormous jellyfish known as Stygiomedusa gigantea been observed.¹⁹⁾

Although the Portuguese man-of-war resembles a jellyfish, it is not one. It isn't even a single animal, really. It is a siphonophore, an animal made up of a group of coexisting creatures. The man-of-war is really made up of four different polyps. The top polyp is a gas-filled bladder that resembles the sails of the formerly popular man-of-war ship.²⁰⁾

Jellyfish can reproduce sexily or asexually. Although there have been hermaphroditic species discovered, they are typically either male or female.²¹⁾

Jellyfish can survive for many hours or several months. One species is said to have a long lifespan. In aquariums, jellyfish often survive longer than they do in the wild. Due to their fragility, jellyfish are more easily caught while they are in the polyp stage, when they are the least susceptible.²²⁾

Plankton, crustaceans, other jellyfish, fish eggs, and tiny fish are some of the foods they eat. Through the same hole in the center of the bell, they feed and urinate.²³⁾

Other jellyfish, sharks, tuna, swordfish, sea turtles, and one species of Pacific salmon are among the many predators of jellyfish.²⁴⁾

Turritopsis nutricula, a particular type of jellyfish, is sometimes referred to as the “immortal jellyfish” since it has the ability to change from the adult medusa stage back to the polyp condition, virtually escaping death. This is achieved by the transdifferentiation of cells, a cell development process.²⁵⁾

The Moon jellyfish is the kind of jellyfish that is most frequently encountered around the coastlines of North America and Europe. Usually blue or pink in color, this variety of jellyfish may be found in seas up to 20 feet (6 meters) deep. It normally has a minor sting, but it can also cause a rash that is itchy and red.²⁶⁾

A dead jellyfish may still sting.²⁷⁾

The earliest multi-organic mammal, jellyfish have existed in the world's oceans for more than 500 million years, long before the dinosaurs.²⁸⁾

Portuguese man-of-wars typically measure 30 feet in length but can grow to be 165 feet (50 meters) long. Man-of-wars are occasionally spotted drifting in groups of 1,000 or more in warm ocean waters. They may collapse their air bladder and momentarily float under the sea to avoid danger.²⁹⁾

The jellyfish that is turned on its side sinks in the water. Instead, it uses its small arms and tentacles to attach to the ocean floor.³⁰⁾