Freedawn Scientia: In the life of a Jellyfish

Personally, I have only ever seen real life jellyfish a few times in the ocean and those were tiny. I have seen a few documentaries about them and I find them a truly incredible creature. So here I am going to try and gather as much information about them and share with you all

So I guess I will start with the simple stuff first….

What is a Jellyfish?

Jellyfish are invertebrates, which, together with corals, gorgonians and anemones belong to a group called the cnidarians (knidÃ© = nettle, from the Greek). This animal group has stinging cells which they use both to capture their prey and also as a form of defence. These cells contain a capsule in the interior of which there is a rolled up filament and a poison. A prey animal makes contact with the surface of the jellyfish, the capsule opens and the filaments are ejected and stick into the prey, injecting their poison.

Jellyfish or jellies are the major non-polyp form of individuals of the phylum Cnidaria. They are typified as free-swimming marine animals consisting of a gelatinous umbrella-shaped bell and trailing tentacles. The bell can pulsate for locomotion, while stinging tentacles can be used to capture prey.

Jellyfish are found in every ocean, from the surface to the deep sea. Scyphozoans are exclusively marine, but some hydrozoans live in freshwater. Large, often colorful, jellyfish are common in coastal zones worldwide. Jellyfish have roamed the seas for at least 500 million years, and possibly 700 million years or more, making them the oldest multi-organ animal.

Jellyfish employ a loose network of nerves, located in the epidermis, which is called a “nerve net”. Although traditionally thought not to have a central nervous system, nerve net concentration and ganglion-like structures could be considered to constitute one in most species. A jellyfish detects various stimuli including the touch of other animals via this nerve net, which then transmits impulses both throughout the nerve net and around a circular nerve ring, through the rhopalial lappet, located at the rim of the jellyfish body, to other nerve cells.

Some species explicitly adapt to tidal flux. In Roscoe Bay, jellyfish ride the current at ebb tide until they hit a gravel bar, and then descend below the current. They remain in still waters until the tide rises, ascending and allowing it to sweep them back into the bay. They also actively avoid fresh water from mountain snowmelt, diving until they find enough salt.

What are Jellyfish made of?

Fascinating, elegant, and mysterious to watch in the water, take a jellyfish out of the water, and it becomes a much less fascinating blob. This is because jellyfish are about 95 percent water.

Lacking brains, blood, or even hearts, jellyfish are pretty simple critters. They are composed of three layers: an outer layer, called the epidermis; a middle layer made of a thick, elastic, jelly-like substance called mesoglea; and an inner layer, called the gastrodermis. An elementary nervous system, or nerve net, allows jellyfish to smell, detect light, and respond to other stimuli. The simple digestive cavity of a jellyfish acts as both its stomach and intestine, with one opening for both the mouth and the anus.

These simple invertebrates are members of the phylum Cnidaria, which includes creatures such as sea anemones, sea whips, and corals. Like all members of the phylum, the body parts of a jellyfish radiate from a central axis. This â€œradial symmetryâ€ allows jellyfish to detect and respond to food or danger from any direction.

Jellyfish have the ability to sting with their tentacles. While the severity of stings varies, in humans, most jellyfish stings result only in minor discomfort.

Jellyfish Taxonomy

Kingdom: Animalia

Phylum: Cnidaria

Subphylum: Medusozoa Petersen, 1979

Classes: Cubozoa, Hydrozoa, Polypodiozoa, Scyphozoa, Staurozoa

Jellyfish belong to Medusozoa, the clade of cnidarians which excludes Anthozoa (e.g., corals and anemones). This suggests that the medusa form evolved after the polyps.

The phylogenetics of this group are complex and evolving. The Medusozoa and Octocorallia are proposed as sister groups according to research published in 2012. That research also proposes coronate Scyphozoa and Cubozoa as a sister clade to Hydrozoa and discomedusan Scyphozoa, which are themselves sister groups. The hydroidolinans are a sister group to Limnomedusae, also called Trachylina. Semaeostomae is paraphyletic with Rhizostomeae. The class Storozoa was the earliest group of Medusozoa to diverge and the Limnomedusae were the earliest Hydrozoa to diverge.

The four major classes of medusozoan Cnidaria are:

> Scyphozoa are often called true jellyfish. They have tetra-radial symmetry. They have tentacles around the outer margin of the bowl-shaped bell, and oral arms around the mouth.

> Cubozoa (box jellyfish) have a box-shaped bell, and their velarium assists them to swim more quickly. Box jellyfish may be related more closely to “true jellyfish” than either are to hydrozoa.

> Hydrozoa may form medusa which resemble scyphozoans (but generally with a velum) and are distinguished by an absence of cells in the mesoglea. However, many hydrozoa species do not form medusa at all (such as hydra, which is hence not considered a jellyfish).

> Staurozoa (stalked jellyfish) do not have a polyp stage, however the medusa is generally sessile, oriented upside down and with a stalk from the “bell” planted to the substrate. Until recently, staurozoa was classified within scyphozoa.

More information on the Classification of Jellyfish

Within the classification of the Animal Kingdom, and within the sub-Kingdom of Metazoans (organisms with tissues, organs and systems of organs with radial symmetry such as the jellyfish, anemones, hydra and corals) there is the Phylum of the Cnidarians, which is the group to which the jellyfish belong.

Within the Phylum of Cnidarians, it is possible to differentiate four large groups, each with its own characteristics. They are:

> The class of Hydrozoa.

They show the phases of polyp and jellyfish alternately. They are generally small in size and they can be colonial or solitary. The siphonophores are included in this class. They are floating colonies of polyp individuals and jellyfish with great and abundant poisonous cells for self-defence which, in certain cases, can be lethal for people. The siphonophores form complex colonies of individuals specialising in different functions; some serve as the flotation organ, others for nutrition, defence or for feeling. Among the best-known species of siphonophores, are the by-the-wind sailor (Velella spirans) or the Portuguese man of war (Physalia physalis), which can produce painful burns for bathers, and even heart failure.

> The class of Esciphozoa.

This is the group of those known as true jellyfish. They are the great marine jellyfish, normally with a very short or even non-existent polyp phase. The following belong to this class: the moon jelly (Aurelia aurita) which is very common in the Mediterranean, the Rhizostoma pulmo which inhabits the Mediterranean and the Atlantic or the fried egg jellyfish (Cotylorhiza tuberculata). Some species are luminescent, such as the purple jellyfish or mauve stinger (Pelagia noctiluca), which can be really striking on a night-time dive. Its eight stinging tentacles can reach a diameter of ten metres when spread out.

> The class of Cubozoa.

A class with few representatives that some authors group together with the esciphozoa. They inhabit the waters of tropical and sub-tropical seas. These are the so-called box jellyfish or sea wasps. They have their umbrella in the form of a cube, with four sides. They have a powerful sting and they may cause death to a person in just a few minutes if he is not treated with an antidote.

> The class of Anthozoa.

All the representatives of this class are polyps, which never adopt the jellyfish stage. It includes corals, madreporas, actinias and sea anemones. They are generally species of a beautiful colour. Some individuals live in isolation, such as the beadlet anemone (Actinia equina), some anemones and the colour tube anemone, (Cerianthus membranaceus), and others form colonies such as the corals or the red gorgonians (Paramuricea sp.)

Chrysaora melanaster, one of the largest jellyfish commonly found in the Arctic, swims underneath the Arctic ice. Credit: K. Raskoff, Monterey Peninsula College, Arctic Exploration 2002, NOAA

Fascinating quick Facts about Jellyfish

1. Some jellyfish can glow in the dark

Many jellyfish have bioluminescent organs, which emit light. This light may help them in a number of different ways, like attracting prey or distracting predators.

2. Jellyfish can clone themselves

If a jellyfish is cut in two, the pieces of the jellyfish can regenerate and create two new organisms. Similarly, if a jellyfish is injured, it may clone itself and potentially produce hundreds of offspring.

3. Some jellyfish are immortal

There are two phases to jelly life: the stationary polyp stage and the mobile medusa phase. It’s the medusa phase that we’re usually referring to when we talk about jellyfish. Typically, jellies start as polyps and develop into medusas, but the Turritopsis nutricula has earned it the nickname “the immortal jellyfish” for having the ability to travel backward to the polyp stage in times of stress.

4. Jellyfish can teach us about efficient underwater propulsion

The movements of bell-shaped jellyfish have provided researchers with a new understanding of propulsion. The flexibility of their umbrella-like bodies allow them to pulse upwards and downwards without expending much energy. Researchers have created biomimetic robots with flexible bells, which may one day lead to better undersea vehicles.

5. Not all jellies have tentacles

The scyphomedusa deepstaria, shown in the video below, doesn’t need tentacles to trap its prey.

6. There’s a giant jellyfish called the pink meanie

The scientific name for this jelly is Drymonema larsoni, but its aggressive sting and distinctive color have earned it the nickname “pink meanie.”

7. Jellyfish don’t have brains

Instead, jellyfish have nerve nets which sense changes in the environment and coordinate the animal’s responses.

8. Jellyfish movements inspired a new way to fly

It’s probably not that surprising that jellyfish have served as inspiration for swimming robots. However, it’s more unusual to see a sea creature inspire a flying machine, but that’s just what happened at New York University.

9. Jellyfish powder has been used to make salted caramel

Turtles eat jellyfish, and larger jellies may eat smaller ones, but are jellyfish fit for human consumption? A group of high school students in Japan came up with a salted caramel recipe that uses powered jellyfish. It’s not vegan for sure, but it is one way to deal with an invasive jellyfish bloom.

10. Glowing jellyfish goo could power medical devices

Another jellyfish-derived product takes advantage of the jellies’ fluorescent protein, and could be used to power medical devices in the future.

11. Jellyfish are surprisingly good at shutting down nuclear reactors

In the past decade, jellyfish blooms have been responsible for shutting down several nuclear reactors, which often rely on ocean water intakes. The jellyfish swarms can clog the intake pipes, forcing facilities to stop operating temporarily.

12. Jellyfish will eat peanut butter

Two Aquarists in Dallas, Texas created a saltwater/peanut butter mix and fed it to moon jellies. Apparently, the jellies found this mix to be an acceptable source of protein. “We would love to claim we conducted this trial with noble purpose, but the truth is that we just wanted to make peanut butter and jellyfish simply to see if it could be done,” the researchers write.

13. Some jellyfish look like trash bags.

14. Jellyfish might take over the ocean

You may have heard that jellyfish are taking over the world’s oceans. However, there’s actually a good deal of debate about this issue among scientists.

List of Jellyfish Species and information

Mangrove Jellyfish

Mangrove jelly fish (Cassiopea xamachana) is so called because it is mostly found in the roots of mangroves in the southern Gulf of Mexico, Caribbean, and other tropical waters. They are also called the Upside Down jellyfish because they tend to settle upside down in muddy and shallow waters. On first sight, they do not really resemble a jellyfish, instead looking more like a sea anemone, or a bluish green flower on the waterbed. However, this appearance also provides the jellyfish with very effective camouflage and protects it from likely predators.

Lagoon Jellyfish

Lagoon jellyfish (Mastigia papau) is another one of the more interesting species of Jellyfish. If you have heard about the Golden Mastiga at the Jellyfish Lake, you may be interested to know that they are actually descendants of the Lagoon jellyfish and over the years have adapted to the conditions of the marine lake. In nature, lagoon jellyfish are found in bays, harbors and lagoons in temperate waters mostly around the Pacific Ocean.

Nomura’s Jellyfish

Nomura’s Jellyfish also known as the Echizen kurage by the Japanese, is a large Japanese Jellyfish whose width is slightly larger than a height of a fully grown man. It can grow up to 2 meters and weigh about 450lb (220 kg) which is as heavy as a male lion. It is the biggest jellyfish in the world.

Sea Nettle Jellyfish

Sea Nettle (Chrysaora) is one of the genus of Scyphozoa class of the phylum Cnidaria. The species of sea nettle we are most commonly knowledgeable about are Chrysaora quinquecirrha, which is mostly found along the east coast of North America in the Atlantic Ocean, and Chrysaora fuscescens, which is mostly found along the west coast of North America in the Northeast Pacific Ocean.

Upside Down Jellyfish

The upside down jellyfish is so called because it tends to stay upside down in shallow, muddy waters that it inhabits. The upside down jellyfish is also called the Mangrove jellyfish because it mainly inhabits the mangroves in the Caribbean and southern Gulf of Mexico among other tropical waters.

The upside down jellyfish looks different compared to any jellyfish you may have seen. This jellyfish looks less like a jellyfish and more like a sea anemone. Its appearance is such that it can be easily mistaken for a bluish green water flower. However, this appearance of the upside down jellyfish is very important for its survival. Its appearance provides it a very good camouflage against its predators.

Comb Jellyfish

Comb jellyfish is, in fact, not a jellyfish at all. Jellyfish as a species belong to the phylum, Cnidaria. On the other hand, comb jellies are an entire separate phylum themselves called Ctenophora. The phylum derives it name from a common characteristic shared by the member species, namely a series of vertical ciliary combs that cover the surface of the animal. The word ctnophora is derived from the Greek words ctene, or “comb”, and phora, or “bearer”. Both, Cnidaria and Ctenophora fall under the same infrakingdom, Coelenterata, and share a number of similarities.

Sand Jellyfish

Sand Jellyfish (Rhopilema asamushi or Rhopilema esculenta) is a species of jellyfish from the genus Rhopilema. Other species of jellyfish belonging to this group include Rhopilema hispidum and Rhopilema nomadic. They are inhabitants of the Indian Ocean and are found in locations like Hong Kong, Malaysia, Japan, China and some parts of the North Atlantic coastline. This species of jellyfish is very to rare to find in marine waters around the American coastlines.

Box Jellyfish

Box jellyfish are marine invertebrates belonging to the phylum Cnidaria. Unlike most jellyfish that belong to the to the class Scyphozoa, box jellyfish belong to the class Cobozoa, so-called because of their characteristic cube-like shape. They are also considered far more complex than their Scyphozoan counterparts. The sea wasp or Chironex fleckeri, is one of the nineteen species that belong to this class.

Sea wasps are best known as the most deadliest creatures in the world, whether on land or in water. Creatures are rated for their deadliness by taking into account two factors:

1. How many people an ounce of the creature’s venom can kill

2. How long it takes you to die from the venom after being bitten, stung, or stuck

In both respect, the deadliness of the sea wasp far outpaces those of any other creature known to man. An ounce of sea wasp venom can kill as many as 60 adult humans and it can cause human death in less than 3 minutes. This means that if you have been stung by the jellyfish while you were swimming, surfing or diving a little further away from the coastline, you may not even be able to reach to the shoreline in time to get medical attention. Only one instance of survival after a sting from the box jellyfish has been recorded and that was Ian McCormick, a New Zealander who survived not one but five stings by the box jellyfish on his arm. However, he has attributed this miracle to divine intervention and seems to be no other scientific explanation for it.

Box Jellyfish are normally found in waters surrounding Australia, New Zealand, Hawaii and Philippines. In Australia, the box jellyfish season usually lasts from October to April every year. In Hawaii, however, there does not seem to be any indication of a box jellyfish season and they are usually sighted throughout the year, usually 8 to 10 days after the full moon night. Box jellyfish are mostly found in shallow waters and prefer being near the intersection of the ocean and rivers, if there are any.

Sea Wasp Jellyfish

The Sea Wasp Jellyfish, also known as the Box Jellyfish, is given the scientific name Chironex fleckeri. They have a cube or bell shaped form and their body is often divided into different segments. It is because of their cube-like shape that they are referred to as box jellyfish.

Their bodies are transparent but some have a pale blue colour to them. They can grow to sizes of around twenty centimetres and weigh around two kilograms. Box jellyfish usually have around fifteen tentacles found on each corner of their cube-shaped bodies and they can grow to lengths of three meters. They are covered with nematocysts, which are stinging cells. A single tentacle of these species can have as many as five thousand nematocysts. These tentacles are used by the sea wasp jellyfish to capture its prey, which are made up of crustaceans and small fish.

Blue Blubber

Blue Jelly (Catostylus mosaicus) is a species of jellyfish in the Rhizostomeae order. It is characterized by a lack of tentacles at the margin of the jellyfish’s body. Instead, it has about 8 oral arms. These oral arms become fused with the body of the jellyfish near the centre of its body. What is fascinating about the oral arms of the blue blubber is that they have minute mouths at the end of the oral arms that themselves transport food to the stomach!

White Spotted Jellyfish

The White Spotted Jellyfish or Phyllorhiza punctata, is a native of Australia and is also known as the Australian spotted jellyfish. It grows to the size of about 45-50 centimeters in diameter, and is ocassionally known to grow to a maximum length of just a little over 60 centimeters in size. They look extremely beautiful with the design of white spots over their translucent gelatinous body and their frilly oral arms add another aspect of charm to their appearance. Additionally, they are fairly harmless and their sting contains only mild venom which does not cause any serious effect or reaction in humans. Application of vinegar can cure the little burning sensation that may be caused by the jellyfish sting. In most cases, just washing the location of the sting with salt water is sufficient measure to rid oneself of the minor effects of the white spotted jellyfish sting.

Turritopsis nutricula (Immortal jellyfish)

The Immortal jellyfish is one of the most unique animals not just within the species of jellyfish, but within the entire history of the animal kingdom. It has actually managed to accomplish the one feat that has been yearned by many and accomplished by none. It appears to have cheated death and hence transformed itself into a perpetually immortal being! Let me explain how this works.

Chironex Fleckeri

The Chrionex Fleckeri is an absolutely amazing but brutal predator of the sea world. It falls under the animal kingdom called Animalia. It is also known as the Sea Wasp or the Box Jellyfish. This jellyfish is an extremely hazardous predator. It is known to kill faster than crocodiles and sharks combined, which are the most dangerous predators of their respective land and water domains. The Chrionex Fleckeri can kill exactly 60 human adults within three minutes. The number is sixty because each person is attacked by one tentacle. Hence, the Chrionex Fleckeri has sixty tentacles, is fifteen feet long and can swim as fast as five feet per second. This is absolutely amazing!

Pelagia Noctiluca

The Pelagia Noctiluca is known to be an extraordinarily beautiful jellyfish. It is said that its luminescence is almost magical and therapeutic during the night for many viewers. This beauty however can be frightening if one considers the possible factor that the Pelagia Noctiluca are known to attack humans. Their stings are extremely painful.

Moon Light Jellyfish

Moon light Jellyfish are known to be extremely quiet eaters. They do not attack humans, perhaps a small sting but not too horrible, more like a crab bite from the waters. The moon light jellyfish can also be referred to as the Aurelia aurita species. This is a large category that may include a variety of types of jellyfishes. It is almost impossible to distinguish the moon light jellyfish from its relatives, unless the genetic material is tested scientifically.

Irukandji Jellyfish

Irukandji Jellyfish, sometimes referred to as Iracongi Jellyfish are extremely toxic and very tiny and found usually around Australia. There are two species which are currently known, these species are the Carukia barnesi and the Malo kingi which has been discovered only recently. These jellyfish are responsible for Irukandji Syndrome which is caused by a group of symptoms intertwined. this syndrome was first researched and recorded by Hugo Flecker in the year of 1952 and the Jellyfish was named after the Irukandji people whose land is along the coastal strip north of Cairns in Queensland, Australia. in 1964 Dr. Jack Barnes made the very first identification of the Carukia barnesi and stung himself as well as his own son and a lifeguard to prove that this tiny jellyfish was the cause of irukanji Syndrome, he was successful.

Moon Jellyfish

The Moon Jellyfish (Aurelia aurita) is also known as the moon jelly, common jellyfish or saucer jellyfish. The name Moonjelly fish can refer to a specific species of jellyfish aurelia aurita, but can also refer to all jellyfish species in the genus Aurelia. Because they are extremely similar to each other and can only be distinguished genetically, the entire species in the genus Aureilia is commonly referred to as Moon Jellyfish. We do not yet know exactly how many species of jellyfish belong to this common genus; new species are discovered regularly.

Aurelia Aurita

Aurelia is commonly referred to as Moon jellyfish. This is the most common species of jellyfish. It is also known as common jellyfish or saucer jellyfish. New species are discovered everyday and there is no count of the many species that belong to this genus. Moon jellyfish can also refer to all jellyfish in the genus Aurelia. Jellyfish are very similar to each other and can be differentiated only genetically.

Ball Jellyfish

Jellyfish are found in practically all the oceans of the world and they come in different colors, shapes and sizes. The general body shape is of a bell or an umbrella, with tentacles dangling below its body. The body consists of more than 95% water, and is of a gelatinous mass, and hence the name. There are about 200 species of this fascinating marine animal, and some new species are still being discovered.

Cannonball Jellyfish

The Cannonball Jellyfish is a member of the Stomolophidae jellyfish species family. This jellyfish gets its name from the cannonball style shape and sized of its body. The cannonball jellyfish has a dome-shaped body which can reach up to 25cm or 10 inches in its diameter and has a rim which can sometimes be colored with a brown or red tinge with the body of the jellyfish itself usually being a milky brown or yellow color. When looking under the body of this jellyfish you will see a cluster of oral arms which extend out around the jellyfishes mouth. These arms primarily exist to propel the jellyfish through the water and to help it catch prey. These jellyfish can be found most commonly from North Americas eastern seaboard right through to Brazil.

Man of War

Looks can be deceptive, and especially if the creature in question is a Portuguese man-of-war. It is very easy to mistake this venomous invertebrate for a jellyfish. At an approximate length of 12 inches and a width of 5 inches, a man-of-war can grow tentacles measuring up to 50m in length, although 30 feet (10 meters) is the average. This jellyfish is generally has a purple-blue tint coloring.

War Jellyfish

The War Jellyfish (Physalia physalis) or the Portuguese Man of War is so called because its shape resembles the Portuguese battleship from the 15th and the 16th century. The Portuguese man of war is usually found in subtropical and tropical waters of the Indian and the Pacific Ocean. It is also found waters around Australia and New Zealand, where it is commonly referred to as blue bubble or blue bottle, because of its purplish blue hue. The War jellyfish belong to the phylum: Cnidaria, class: Hydrozoa, order: Siphonophora and family: Physaliidae.

Blue Bottle Jellyfish

Blue bottle jellyfish is so-called in Australia and New Zealand where it is also commonly known as Blue Bubble Jellyfish. Elsewhere in the world, this creature is usually called the Man of War or Portuguese Man o’ War, since it resembles a Portuguese battleship with a sail.

Lions Mane Jellyfish

Lions mane jellyfish, or Cyanea capillata, has made a sensational appearance in literature, most notably in Sherlock Holmes’s ‘The Adventure of the Lions Mane.’ However, lions mane jellyfish is nowhere close to as dangerous as it is made out to be in popular culture. A sting from the lions mane jellyfish is not only incapable of causing human deaths; all it does is cause an itchy rash and mild burning sensation. Although the rash can be painful for sensitive individuals and the toxins in the venom may cause an allergic reaction, the stings from a lions mane jellyfish can be treated by application of vinegar.

Sun Jellyfish

The Sun Jellyfish a member of the marine life species that is very unique. It is different from other fish based on its shape and other factors making it one of the most individual water forms in the world. The Jellyfish is a species belonging the scyphozoan class of marine life in the invertebrates. The name of scyphozoan is derived from the Greek name “skyphos” meaning “a drinking cup” and is used to describe the jellyfish based on their shape.

Square Jellyfish

The square jellyfish is a vivid description of the anatomical appearance of this kind of jellyfish which appears cuboidal in shape. Usually the right kind of name for identification is the box jellyfish. They belong to the Cubozoa class and the number of species total to over 19. The best known kind of square (or as from here on end box) jellyfish is the Chironex fleckeri which holds the most toxic poison in the entire animal kingdom. The venom targets the cardio-respiratory system. The breathing muscles collapse and the stung person dies from suffocation, shock and from the pain which has been described as extremely overbearing. Statistically, the box jellyfish is the prime killer, ahead of all other animal dangers including sharks and the salty water crocodiles in the Australian region where they are found in abundance.

Physalia Jellyfish

The Physalia jellyfish, scientifically regarded to as Physalia physalis is the term used to refer to the Portuguese Man ‘O War. It is among the most feared of jellyfish probably because of its stinging and tropical abundance. It is mostly located in the salt water bodies in the tropics. The Atlantic and Pacific oceans are the dense water bodies that have an abundance of this species of jellyfish.

King Jellyfish

The term king is used in various citations in the animal kingdom in reference to the animal with the biggest kind of superiority. With snakes, the term king is used in reference to the most dangerous venomous snake. In this case, it is the king cobra. Not that it is the most venomous snake, but the dosage that it administers is the most fatal. Looking at it in that similar context, the king jellyfish can easily be the box jellyfish.

Cassiopeia Jellyfish

Cassiopeia is not the common name used to refer to this species of jellyfish. It’s the genus name, for the Cassiopeia xamachana, the upside down jellyfish. It is an anatomical beauty from the rarity of its physique. From its naming, it’s apparent that this jellyfish has an upside down orientation. Its tentacles hang over its head. They are short and reach a length of 14 inches. It has a transparent body, though not a pale blue one like most other distant relatives. It is a carnivorous species, feeding on small fish and invertebrates though it doesn’t mind taking a bite of zoo plankton every once in a while.

Jellyfish Pictures

Jellyfish Documentaries

Vicious Beauties – The Secret World of the Jellyfish

Attack of the Giant Jellyfish

BBC Documentary – Super Jellyfish Nature Documentary

PDF Documents on Jellyfish

> Jellyfish Biomass in the Biological Pump
> Reproduction and life History Strategies of the Common Jellyfish
> Diving Behaviour of Jellyfish Equiped with Electronic Tag
> Jellyfish IDs
> Jellyfish Information Poster
> Spain – Jellyfish Guide
> Jellyfish Nervous System

Jellyfish Questions and Answers

What do jellyfish feed on?

Jellyfish are carnivores and can increase in size rapidly and create a large number of individuals when food is abundant. However, if food is scarce, they can become smaller. These animals, of a gelatinous consistency, have a very unsophisticated anatomy which is nevertheless very effective. They feed mainly on zooplankton, small crustaceans, although some small fish and other jellyfish also form part of their diet. It is a strange sight to see the jellyfishâ€™ latest prey inside its body before it is digested.

How does the defence system of the jellyfish work?

The tentacles, with their stinging cells, serve as defence and as a powerful weapon for capturing prey. When they come into contact with their victims, the nematocysts (cells loaded with poison) present in the tentacles, release their harpoons or filaments which they have inside them and, through these, a toxic substance is released which paralyses the prey. The oral arms help in the capture and ingestion of the captured animal.

Is it true that the jellyfish have proliferated because there are fewer turtles, which feed on them?

Among the predators of the jellyfish, the following have been identified: ocean sunfish, grey triggerfish, turtles (especially the leatherback sea turtle), some seabirds (such as the fulmars), the whale shark, some crabs (such as the arrow and hermit crabs), some whales (such as the humpbacks). Some other cnidarians also feed on jellyfish such as anemones, certain nudibranches (small molluscs without shells) which may even take over their stinging cells to use in their own defence.

How do they arise and where do they live?

Jellyfish are inhabitants of the tropical seas and of the cold waters of the Arctic. They have been there for over 650 million years. Jellyfish are pelagic animals, that is to say that they live in the open seas, and although they can propel themselves with rhythmic motions of their umbrella, they move basically at the mercy of the currents of the sea.

So I know you are all probably wondering at this point….what is the most dangerous jellyfish? Well wonder no more, here is the

Top 5 most Dangerous Jellyfish

5. Sea Nettle (Chrysaora)

The Sea Nettles are common on both coasts of North America. They are probably best known around the Chesapeake Bay are of on the US East coast. Here they aggregate to forming huge blooms (thatâ€™s the technical term for a bunch of jellyfish) during the summer months becoming a menace to swimmers.

The sea nettles are large jellyfish reaching up to 1ft (30cm) across. They have 24 tentacles which can measure well over 6ft (2m) in length and it is on these that the infamous stingers reside.

The sting from a sea nettle can be extremely painful and leave a painful rash on the skin for around an hour. They are not generally dangerous though and medical assistance is very rarely needed. Reports of stings from more exotic Chrysaora species have been more serious.

4.Lionâ€™s Mane Jellyfish (Cyanea capillata)

The lionâ€™s mane jellyfish is the largest species known to man. With a bell reaching up to 8 ft (2.5m) or more across and tentacles trailing over 100 ft (30m) these monster jellies can weigh around a quarter ton. They also occur in large swarms meaning a convergence of these on your local beach is going to put it out of bounds.

The lionâ€™s mane is a coldwater species and can be found throughout the North Atlantic, including the UK. It also occurs in cooler Australian waters where some lifeguards have allegedly taken to wearing pantyhoses â€“ partly to protect against the sting.

The sting itself can be highly painful and many sources (including National Geographic) describe it as being potentially fatal. What is known is that, like most jellyfish, the stings remain active for a considerable time after death. In a recent incident at a beach in New Hampshire, USA, a single washed up lionâ€™s mane jellyfish broke up and the fragmented tentacles stung a reported 150 people.

3. Portuguese Man oâ€™ War (Physalia physalis)

Strictly speaking the Portuguese Man oâ€™ War, or bluebottle, is not a true jellyfish. It isnâ€™t actually even a single animal. It is actually a whole colony of organisms working together in peace and harmony. The name comes from the air filled bladder that acts as a float and sail â€“ this was thought reminiscent of the 17th century naval ships called men-of-war. I think the Portuguese bit also comes from the ship â€“ I lived in Portugal for a while and never saw any of these critters.

In Australia they call it a blue-bottle because itâ€™s blue.

The Man oâ€™ War is found throughout the oceans of the world and has been sighted as far north as Scotland, thanks largely to the warm waters of the Gulf Stream.

The sting of the Portuguese Man oâ€™ War is both serious and common with up to 10,000 stings per annum in Australia alone. The sting itself is characterised by a painful raised whip-like welt across the skin. These can last from an hour to several days. The main risk is from systemic effects of the venom. In severe cases intense pain followed by fever, shock, and impaired heart and lung function leading to possible death may occur.

2. Irukandji Jellyfish (Carukia barnesi)

What the Irukandji jellyfish lacks in size it makes up for in the power of its venom. The name is derived from the Irukandji people of North Australia, as this is where the jellyfish was first observed. However, it appears to be much more widespread than this with specimens allegedly found as far away as the British Isles.

Measuring only 5mm (0.2 ins) across and with tentacles less than 1 metre (3 ft) it is one of the smallest members of the box jellyfish family. The venom though is insanely powerful; it is reputedly the most venomous animal toxin on earth, over 100 times more powerful than that of the cobra. In addition to this the Irukandji Jellyfish is unique in having stingers on its bell as well as tentacles.

The only reason this critter isnâ€™t at the top of the list is its small size. Despite this the sting is without doubt potentially lethal. Often one sting will not kill as long as appropriate treatment is given. In non fatal stings Irukandji syndrome may develop with delightful symptoms such as excruciating muscle cramps, severe pain in the back and kidneys, burning sensation of the skin and face, vomiting, headache and increased heart rate. Victims have also described a â€ feeling of impending doomâ€. The good news is that apparently, the sting itself isnâ€™t too painful!

1. Box Jellyfish (Chironex fleckeri)

It seems to go without saying that the most poisonous, deadliest and meanest of all the jellyfish inhabits Australia. The variety of box jellyfish known as the sea wasp or marine stinger is widely regarded as one of the most deadly creatures on earth. Along with other box jellies they have been responsible for at least 5,568 deaths recorded since 1954. The Australian variety causes around 1 death a year on average with a further 100 in South East Asia.

As with so many of the deadliest animals it is said that from certain angles there are skull-like marking â€“ in this case on the largely transparent bell. The 15 tentacles can reach up to 3 metres (10 ft) long and each is covered in around half a million venom infused, microscopic darts. It is estimated that each animal contains enough venom to kill 60 adult humans. The venom acts fast too and it can kill within minutes causing cardiovascular collapse. It also attacks the nervous system and skin cells.

The actual sting has been compared to being branded with a red hot iron. It is said that the pain can be so severe that it may result in shock leading to drowning or heart failure on its own. Whilst stings are often survived pain can continue for weeks and there may be permanent scarring resembling whip marks across affected areas.

In the life of a Jellyfish

Thursday 4 December 2014