Types Of Jellyfish
How Many Different Types of Jellyfish Are There?
It may be surprising, but there are literally hundreds, even thousands of different types of jellyfish in the world’s waters today. Some are familiar and others are rare. Some can be found in tropical waters and others in frigid oceans. Find out all you need to know about this fascinating creature.
All types of jellyfish are made up of mostly water – up to 97% of their body. They appear to be floating in the water and cannot see you if you’re swimming nearby. A jellyfish has no brain, heart, blood or gills – but they do have the ability to eat and smell. A mouth (or mouths) on their body collects zoo plankton, eating as they float around.
Since a jellyfish has no backbone (or any bones at all), they are classified as an invertebrate. Their alternative name of Cnidaria comes from the Greek word for “stinging nettle” – cnidos. Their reputation for danger is apparently long established.
Jellyfish have tentacles much like a squid, hanging off of their bell-shaped body. The tentacles help to capture food and are the source of the stings jellyfish are famous for. The arctic lion jellyfish has tentacles up to 100 feet in length. Others range in length depending on the size and age of the creature.
Jellyfish stings actually come from a cell that they carry around. That cell has a nematocyst inside covered by a lid, which is activated by a sensory hair. When anything gets too close and tickles or moves the sensory hair, the lid pops and the nematocyst flies out like a bullet, delivering a sting in seconds. Once you have irritated this defensive system, you are in for a sting.
Not all types of jellyfish are poisonous though. Some are so harmless that they actually carry tiny sea creatures underneath and amidst their tentacles, offering protection. Other types can kill a human within 3 minutes.
A jellyfish swims by collecting water under their bodies, then pushing it out with the coronal muscle. The force of the water one way pushes the jellyfish in the opposite direction - a very efficient mode of transportation.
Jellyfish come in many colors of the rainbow, from blue to purple, red, orange and brown. Some even glow in the dark. The creature can be found in freshwater all over the globe, with the possible exception of Africa and is also abundant in the oceans.
The most common jellyfish seen in aquariums around the world is the moon jelly or Aurelia Aurita. They are about 6 to 8 inches in size and 20 inches in diameter. Moon jelly stings are mild and not fatal.
The Lion’s Mane jellyfish or Cyanea capillat is common in myths and stories – the stereotypical jellyfish. Despite its name, this jelly prefers the cold, winter waters. It has a bell about 6 to 8 inches and arms that are a reddish-brown color. It will sting, but the attack will produce a rash that is more irritating than painful.
Another strangely beautiful type is the upside down jellyfish (also called the Mangrove Jelly). They float upside down when compared to other species and often are mistaken for blue water flowers. They reside in shallow waters and rest on the bed or bottom, holding their tentacles up to the sunlight.
Often thought of as a jellyfish, the Portuguese Man of War (or Physalia physalis) is not a true type. It looks similar, with a bell shaped body and tentacles. A Portuguese Man of War will also sting if you venture too close, and that may result in shock and fever as well as a severe rash.
Truly fascinating, the many types of jellyfish can be studied and compared for an enormous amount of time. Many are not threatening to humans, but it’s best to know which one you will encounter ahead of time to avoid a painful sting. Find out what types of jellyfish live near your home and pay them a visit to learn more.