When you mention jellyfish, most people conjure up the image of a round, transparent or opaque sea creature with a large number of tentacles, but this isn’t always true; jellyfish come in a wide variety of sizes, shapes and colours.
Jelly fish are one of the most amazing creatures in the oceans. They make ltheir home in the oceans and seas on the planet and are found from the bottom of the sea to the surface. Jellyfish can be found in the coldest waters of the Arctic Oceans and the warmest seas around Australia, but they are very specialized and can’t survive in different environments other than the one they are best suited.
There have been about 1000-1500 species of jellyfish found so far and new species are found frequently. One of the most fascinating things about jellyfish is they are one of the oldest living creatures, having existed even before dinosaurs.
Most people have seen jellyfish, either washed up on a beach or in an aquarium. This is because they are the most populous creature in the sea. They can be very dangerous to people as they can sting and poison their victims. Not all stings are fatal to people as it depends on the variety of jellyfish that did the biting. Some stings are painless, while others can cause extreme pain and even kill the person they sting.
Jellyfish are found in many shapes and colours, including purple, blue, brown, orange and red and some can glow in the dark. The colours are the result of the fluorescent chemicals in their bodies. The situation the jellyfish is in can determine their colour and some use their colours to attract others of the same species when mating or use it to frighten off predators. Jellyfish are made up of 97% water and can eat and smell, but they don’t have a brain, gills, blood or heart. They have a mouth, or more than one, to collect the zooplankton they eat.
Common types of jellyfish include:
This is the jellyfish that are most common in aquariums. They are also known as moon jellyfish. They are about 3 to 20 inches in diameter and about 6 to 8 inches in size. The moon jellyfish is transparent and white, with, at its centre, a cloverleaf pattern in pink or orange, and their bell is saucer shaped. They have four pink horseshoe markings (actually their gonads). Their sting causes mild discomfort to people and gives a prickly, burning sensation and is not fatal.
The Lion’s Mane Jellyfish lives in cold waters, its bell is about 6 to 8 inches in diameter and the tentacles are reddish-brown in colour. This jellyfish has eight clusters of tentacles which hang down from underneath their oral arms. The sting of the Lion’s Mane Jellyfish feels like a prickling, burning sensation and produces a rash.
The Mangrove Jellyfish, or upside down jellyfish, floats upside down in the water and are often thought to be blue water flowers. They are found in shallow waters where they lie on the sea bed with their tentacles held up towards the sunlight.
The Portuguese Man of War is not a true jellyfish even though they look the same with a blue or purple bell shaped body and dark red or purple tentacles. They range in size from 1 inch to 12 inches in diameter. The sting of a Portuguese Man of War causes shock, fever and a severe rash.
The Big Pink Jellyfish lives at the surface of the water where it floats upside down. It can grow between 4 or 5 inches up to 3 feet and is pale pink in colour.
This beautiful jellyfish is purple or yellow in colour and grows to 5 inches in diameter.
The cannonball, or cabbage head, jellyfish have round, white bells with a brown or purple band of pigment at the base. They have a round body with a red and brown pattern which can be white at times. They don’t have tentacles but feed using oral arms. They are about 8 to 10 inches in diameter and their sting is harmless to people. They do clog up fishing nets often in the areas where they live.
The Mushroom jellyfish is similar in appearance to the cannonball jellyfish but with a softer, flatter body and no brown band. They grow bigger as well, up to 10 to 12 inches in diameter. They don’t have tentacles either; they have long finger-like limbs, somewhere between tentacles and oral arms. This species is also harmless to people.
This is the biggest known jellyfish species. It also has vivid colouration but the red hues vary with age. The Tiburonia granrojo has a very big body but has much shorter tentacles compared to other species of jellyfish, though they are still long enough to catch its prey. It feeds on plankton and small fish.
Purple Striped Jellyfish
These jellyfish are native to the Californian coastline. It is, as its name suggests, purple with stripes on its body. When they are young the stripes are light pink and it isn’t until they get older that they become purple.
Stinging Nettle Jellyfish
This jellyfish is semi-transparent and its body is covered in small spots and red-brown coloured stripes descending from the middle of its body. Some stinging nettle jellyfish don’t have the body stripes and these look whiter. These jellyfish range in size from 1 to 12 inches in diameter.
This tiny jellyfish ranges in size from less than 1 inch to 4 inches in diameter and is very transparent. The Beroe, a type of comb jelly fish, isn’t as transparent and is orange or reddish brown in colour. They are more cone shaped than bell shaped and can reach 6 inches in size.
This is a tiny transparent jellyfish, no bigger than a small coin, can be very difficult to spot unless you are looking carefully.
The “By the Wind Sailor” is has a dark blue flotation device and uses a transparent membrane as a sail. It is no bigger than 3 inches in size.
These are just a few of the enormous and varied species of what we call jellyfish. It is well worth a visit to an aquarium to see them in all their glory but watch out for them on the beach, you could get a nasty sting!