JellyFish Facts

Cnidaria Jellyfish

Cnidaria Jellyfish picture

Cnidaria Jellyfish

Cnidarians have great diversity when it comes to their forms. Cnidarians range from Colonial Siphonophores and large Medusae as well as Corals, Box jellyfish and other jellyfish and feathery Hydroids. All of these creatures share one thing in common which is their ability to sting prey or predators with their stinging cells located on their tentacles or their body. These stinging cells are known as nematocysts. It is presumed that all of the Cnidarians inherited their nematocysts from one single common ancestor rather than multiple closely related family members.

The name Cnidaria actually hails from the Greek word "cnidos" which literally means stinging nettle. If you touch some of these Cnidarians it will become rather apparent to you why they got their name as their nematocysts shoot barbed threads laced with poison into your flesh. There are literally thousands of these Cnidairan species living throughout the Worlds Rivers, streams, lakes and oceans spanning right from the tropics right down to the poles from the glistening surface of the water down to the deep, dark depths of the sea floor. Some species of Cnidarian even have the ability to burrow.

The four Major groups of Cnidarians are the Anthozoa, Cubozoa, Hydrozoa and Scyphozoa. The Anthozoa group of Cnidarians consists of creatures such as true c orals, sea anemones and sea pens and are most likely the most famous group of Cnidarians. These Cnidarians build beautiful reefs in the tropical waters and are commonly found as fossils with some being as old as 550 million years old. The corals that we see today which are living didn't appear until around the middle of the Triassic period which is around the same point of time where the first of the dinosaurs began to evolve.

The cubozoans look much like the basic jellyfish but have the ability to swim at impressive speeds and manoeuvre around objects as well as being able to see things without having a brain. Box jellyfish fit into this category as Cubozoans have a square or cubed shape when viewed from above. These species have four tentacles at each corner of their body and these are evenly spaced, some may have bunches of tentacles at each corner instead. The Chionex Fleckeri is one of these Cubozoans and is found in Australia, it is amongst the deadliest creatures on the planet and has been the cause of many human fatalities.

Hydrozoa are the most diverse group consisting of creatures such as Fire Corals, Hydroids, Siphonophores as well as Medusae. Scyphozoa are the true jellyfish which are recognisable by the majority of beach-goers and are graceful but can at times be deadly creatures. The sting from these Scyphozoa may cause anything from the appearance of skin rashes to muscle cramps and even possibly death. These jellyfish range in size anywhere from a tiny 12 millimetres to over two metres across. Jellyfish have no head, no skeleton and lack any special organs to assist with breathing or excretion.

All of these Cnidarians can be found all over the world and can be breathtaking to witness. To gather more information on Cnidarians visit Jellyfish Classification and learn more about jellyfish.

Learn more about Jellyfish, different Jellyfish Species, general Jellyfish Information, Jellyfish Pets and Jellyfish Safety




Written by and Sudarsana Sinha.

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