Amazing World of Jellyfish

Jellyfish are found all over the world, from surface waters to the deep sea.

Scyphozoans (the "true jellyfish") are exclusively marine, but some hydrozoans with a similar appearance live in freshwater. Large, often colorful, jellyfish are common in coastal zones worldwide. The medusae of most species are fast-growing, and mature within a few months then die soon after breeding, but the polyp stage, attached to the seabed, may be much more long-lived. Jellyfish have been in existence for at least 500 million years,[1] and possibly 700 million years or more, making them the oldest multi-organ animal group.

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Blue jellyfish (Cyanea lamarckii)

Translucent body with blue-purplish ring inside. Masses of tentacles on the margin. Up to 300mm in diameter. This species is found in the pelagic zone off the west coast of Scotland, the North Sea, the English Channel, and the Irish Sea, sometimes with the more common lion's mane jellyfish, (Cyanea capillata).

uncommon. Stings!

Anatomy of Jellyfish

The main feature of a true jellyfish is the umbrella-shaped bell. This is a hollow structure consisting of a mass of transparent jelly-like matter known as mesoglea, which forms the hydrostatic skeleton of the animal. 95% or more of the mesogloea consists of water, but it also contains collagen and other fibrous proteins, as well as wandering amoebocytes which can engulf debris and bacteria.

The mesogloea is bordered by the epidermis on the outside and the gastrodermis on the inside. The edge of the bell is often divided into rounded lobes known as lappets, which allow the bell to flex. In the gaps or niches between the lappets are dangling rudimentary sense organs known as rhopalia, and the margin of the bell often bears tentacles.

Did you know?

We are a lot of Water

The key to our survival is our ability to blend in with the ocean, which is achieved with bodies made up of 95 - 98% water.

We are old - 600 Milion

Before the dinosaurs, trees, or even fungi, there were jellyfish. They are the oldest multi-organ animal, surviving all five of Earth’s mass extinction events.

You know less than 1%

So far, over 2,000 species of jellyfish have been discovered and identified, but some believe that here could be 300,000 species of us

May be immortal

Found in the Mediterranean Sea and in the waters of Japan, Turritopsis dohrnii can undergo cellular transdifferentiation which means it can cheat death.

We live in the water, we are the water!

The key to their survival is their ability to blend in with the ocean, which is achieved with bodies made up of 98% water. Not only that, but they also have no brain, blood, lungs, or heart. Instead of a brain, jellyfish have an elementary nervous system with receptors that detect light, vibrations, and chemicals in the water. Along with the ability to sense gravity, these capabilities allow the jellyfish to navigate. Absorbing oxygen through their gelatinous skin, they have no evolutionary need for lungs, heart, or blood. Some species of jellyfish do have eyes and "teeth," or rather thin hairs that pull in and bite down on their food.

We've been here for a long time.

Before the dinosaurs, trees, or even fungi, there were jellyfish. They are the oldest multi-organ animal, surviving all five of Earth’s mass extinction events. This includes the Great Dying, also known as the Permian-Triassic extinction event, which wiped out 70% of life on our planet. Despite having no bones and therefore no fossils, scientists have dated them by looking for what are called "soft fossils.” These are when organisms leave an imprint in rock after being quickly buried in sediment. Some research has even suggested that jellyfish could be older, possibly 700 million years.

There could be a lot of us

So far, over 2,000 species of jellyfish have been discovered and identified. However, much like how the Drake equation estimates the number of extraterrestrial civilizations in the Milky Way Galaxy, scientists use a similar system to guess the number of jellyfish species in the unexplored ocean. Some jellyfish are also so microscopic that they are practically invisible. The smallest are those in genera Staurocladia and Eleutheria, measuring only 0.5 millimeters (0.02 in) in diameter. But the world's largest is the Nomura's jellyfish with a diameter of 2 meters (6.5 ft) and weight of up to 200 kilograms (440 lb).

Immortal Jellyfish

As far as scientists can tell, the Turritopsis dohrnii jellyfish might be able to cheat death. Found in the Mediterranean Sea and in the waters of Japan, this species can undergo cellular transdifferentiation. When threatened, sick, or old, it begins a process that reverts its cells to a polyp or adolescent stage and then forms a new polyp colony. Basically, creating younger versions of itself that will become identical to its mature adult form when grown. A jellyfish fountain of youth! Yet, other species aren’t so lucky. Most jellyfish only live for about a year, with some only living for a couple of days.

We can swim pretty good!

watch us swim and lean how to swim like us.

Some of us can glow!

How the bioluminescence work.

The glow occurs when a substance called luciferin reacts with oxygen. This releases energy, and light is emitted. An enzyme called luciferase facilitates the reaction. Sometimes luciferin and luciferase are bound together with oxygen into a single molecule, or photoprotein.

About 50% of jellyfishes are bioluminescence.

Meet our cousin!

The Portuguese man o' war

(Physalia physalis)

The name man o' war comes from the man-of-war, a sailing warship, and the animal's resemblance to the Portuguese version (the caravel) at full sail.

The Portuguese man o' war is a conspicuous member of the neuston, the community of organisms that live at the ocean surface. It has numerous venomous microscopic nematocysts which deliver a painful sting powerful enough to kill fish, and has been known to occasionally kill humans.

Although it superficially resembles a jellyfish, the Portuguese man o' war is in fact a siphonophore. Like all siphonophores, it is a colonial organism, made up of many smaller units called zooids. All zooids in a colony are genetically identical, but fulfill specialized functions such as feeding and reproduction, and together allow the colony to operate as a single individual.

Anatomy of The Portuguese man o' war

Thank you for reading about us!

See you in the ocean!