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15 Interesting Facts About Jellyfish

Enter the enchantment of the water, where ethereal beings float across the depths with hypnotic grace. Jellyfish dominate as the delicate, ethereal denizens of marine habitats among these enthralling species. They emit an ethereal beauty that intrigues and mystifies with their translucent bodies and throbbing tentacles.

Jellyfish drift smoothly with ocean currents, each one a work of natural creativity. They enchant us with their exquisite movements and ethereal radiance, from the graceful moon jellyfish to the entrancing lion’s mane jellyfish.

These intriguing species have adapted to flourish in a world that is mostly unknown to us, enticing us to discover their secrets and marvel at their fascinating life. Prepare to be immersed in the enthralling world of jellyfish, where the ordinary becomes extraordinary and reality combines with a compelling dreamy condition.

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

Jelly Fish in Ocean Park.jpg , , via Wikimedia Commons

Jellyfish can be found wherever on the planet, from the surface to the deep oceans. Scyphozoans which are true jellyfish are only found in the sea, however certain freshwater hydrozoans with similar appearances exist. Large, multicoloured jellyfish are abundant in coastal areas around the world.

Most species’ medusae develop quickly, mature in a few months, and perish soon after reproducing, while the polyp stage, which is anchored to the seafloor, may live much longer.

2. The main feature of a true jellyfish is the umbrella-shaped bell

The umbrella-shaped bell is the distinguishing feature of a real jellyfish. This is a hollow structure made up of a mass of transparent jelly-like materials known as mesoglea, which serves as the animal’s hydrostatic skeleton. Water makes up 95% or more of the mesogloea, but it also contains collagen and other fibrous materials, as well as wandering amoebocytes that can ingest debris and germs.

The mesogloea is bounded on the outside by the epidermis and on the inside by the gastrodermis. The bell’s edge is frequently separated into rounded lobes called lappets, which allow the bell to flex. Dangling rudimentary sensory organs known as rhopalia can be found in the crevices or niches between the lappets, and tentacles can be found on the bell’s border.

3. Most jellyfish do not have specialized systems

Jellyfish jelly fish.jpg , , via Wikimedia Commons

Most jellyfish lack specific osmoregulation, respiration, and circulatory systems, as well as a central nervous system. Nematocysts, which administer the sting, are mainly found on tentacles, but they can also be found around the mouth and stomach of real jellyfish. Because enough oxygen diffuses through the epidermis, jellyfish do not require a respiratory apparatus.

They have little control over their movement but can navigate by using the pulsations of their bell-like body; some species are active swimmers most of the time, while others float. The rhopalia have primitive sense organs that can detect light, water-borne vibrations, odour, and orientation.

 In the epidermis, a loose network of nerves known as a “nerve net” exists. Although most animals are deemed to lack a central nervous system, nerve net concentration and ganglion-like structures could be considered to constitute one.

A jellyfish detects stimuli and sends impulses to other nerve cells via the neural net and a circular nerve ring. Pacemaker neurons in the rhopalial ganglia govern swimming rate and direction.

4. Box jellyfish eyes are a visual system that is sophisticated in numerous ways

The visual systems of box jellyfish are diverse and sophisticated, including several photosystems. Given the extensive inter-species morphological and physiological variance, there is likely significant variation in visual features amongst box jellyfish species. Box jellyfish eyes vary in size and shape, as well as the number of receptors (including opsins) and physiology.

Box jellyfish feature elaborate lensed eyes, similar to those found in more developed multicellular creatures such as vertebrates. Their 24 eyes are classified into four morphological groups. Two enormous, morphologically distinct medial eyes with spherical lenses, a lateral pair of pigment slit eyes, and a lateral pair of pigment pit eyes comprise these categories.

The eyes are located on rhopalia, which are sensory organs of the box jellyfish that emerge from the chambers of the exumbrella (the body’s surface) on the side of the jellyfish’s bells. The two huge eyes on the club’s mid-line are considered complicated since they contain lenses. The four remaining eyes are basic and are located laterally on either side of each rhopalium.

5. The lion’s mane jellyfish is the largest jellyfish

Lion’s mane jellyfish in Gullmarn fjord at Sämstad 3.jpg , CC0, via Wikimedia Commons

One of the largest known jellyfish species is the lion’s mane jellyfish, often known as the gigantic jellyfish. It is restricted to the chilly, boreal seas of the Arctic, northern Atlantic, and northern Pacific Oceans. It may also float into the southwestern Baltic Sea, where it will be unable to spawn due to the low salinity.

The largest reported specimen was measured off the coast of Massachusetts in 1865 and had a bell 210 centimetres in diameter and tentacles 36.6 m long. Lion’s mane jellyfish have been reported in the main bays of the United States East Coast for some time below 42°N latitude.

6. Jellyfish have a complex life cycle which includes both sexual and asexual phases

Jellyfish have a complex life cycle that includes both sexual and asexual stages, with the medusa being the most common sexual stage. Sperm fertilize eggs, which grow into larval planulae, then polyps, ephyrae, and finally adult medusae. Certain stages may be bypassed in some animals.

If there is an adequate amount of food, jellyfish spawn on a regular basis until they reach adulthood. Light controls spawning in most species, with all individuals spawning around the same time of day; in many cases, this occurs at dawn or dusk. Jellyfish can be either male or female. In most situations, adults release sperm and eggs into the surrounding water, where the unprotected eggs hatch into larvae.

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7. The jelly is the most energy-efficient swimmer of all time

Cyanea capillata-1 hg 06.jpg , , via Wikimedia Commons

Jellyfish, such as the moon jelly Aurelia aurita, have been demonstrated to be the most energy-efficient swimmers of all animals. They move through the water by expanding and contracting their bell-shaped bodies radially in order to push water behind them.

They form two vortex rings by pausing between the contraction and expansion phases. Muscles are utilized for body contraction, which forms the first vortex and propels the animal forward, but the mesoglea is so elastic that expansion is propelled only by relaxing the bell, which releases the energy accumulated from contraction.

The method, known as passive energy recapture, only works in microscopic jellyfish travelling at slow speeds, allowing the animal to travel 30% farther on each swimming cycle.

In similar experiments, jellyfish had a 48 per cent lower cost of transport in terms of food and oxygen intake versus energy used in movement than other animals. One reason for this is that the majority of the bell’s gelatinous tissue is dormant and consumes little energy while swimming.

8. Jellyfish are carnivorous

Jellyfish, like other carnivorous cnidarians, feed on planktonic animals, crustaceans, small fish, fish eggs and larvae, and other jellyfish, swallowing food and voiding unprocessed waste from the mouth. They hunt passively by utilizing their tentacles as drift lines or by sinking into the water with their tentacles spread widely; the tentacles, which contain nematocysts to stun or kill the prey, may then flex to assist in bringing the prey to the mouth.

Their swimming method also aids in prey acquisition; when their bell swells, it sucks in water, bringing more possible animals within reach of the tentacles. Aglaura hemistoma is an omnivorous species that feeds on microplankton, which is a mixture of zooplankton and phytoplankton (microscopic plants) such as dinoflagellate.

9. Other species of jellyfish prey on jellyfish 

The pink jelly fish (50273920688).jpg , , via Wikimedia Commons

Other jellyfish species are among the most prevalent and significant jellyfish predators. Jellyfish that wander into their range may be eaten by sea anemones. Tunas, sharks, swordfish, sea turtles, and penguins are among the other predators. Foxes, other terrestrial mammals, and birds consume jellyfish washed up on the beach.

However, few creatures prey on jellyfish in general; they can be called apex predators in the food chain. Once jellyfish become dominant in an ecosystem, such as through overfishing, which eliminates predators of jellyfish larvae, there may be no obvious way to restore the previous balance: they eat fish eggs and juvenile fish and compete with fish for food, preventing fish stocks from recovering.

10. Jellyfish are armed with nematocysts, a type of specialized stinging cell

Contact with a jellyfish tentacle can cause millions of nematocysts to penetrate the skin and inject venom, however, only some species’ venom is toxic to humans. Researchers discovered a jellyfish species named Cassiopeia xamachana that, when activated, releases tiny balls of cells that float around the jellyfish hurting anything in its path. Cassiosomes are defined as “self-propelling microscopic grenades” by researchers.

Most jellyfish stings are not fatal, but stings of some box jellyfish (Irukandji jellyfish), such as the sea wasp, can be fatal. Stings can cause anaphylaxis (a type of shock), which can be fatal. Jellyfish kill 20 to 40 people per year in the Philippines alone.

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11. Jellyfish blooms can have a significant impact on community structure

In particular environmental conditions such as ocean currents, nutrients, sunlight, temperature, season, prey availability, reduced predation, and oxygen concentration, jellyfish create huge masses or blooms. Jellyfish are gathered together by currents, especially in years with unusually large populations. Jellyfish can detect sea currents and swim against them to form blooms.

Jellyfish blooms can have a substantial impact on the structure of a community. Some kinds of carnivorous jellyfish feed on zooplankton, while others graze on primary producers. Reductions in zooplankton and ichthyoplankton caused by a jellyfish bloom can reverberate up the food chain.

Jellyfish populations with a high density can outcompete other predators and decrease fish recruitment. Jellyfish grazing on primary producers can also disrupt energy transfer to higher trophic levels.

11. Most jellyfish are marine animals

Jelly Fish (20725226232).jpg , , via Wikimedia Commons

The majority of jellyfish are marine organisms, however, a few freshwater hydromedusae exist. Craspedacusta sowerbii, a global hydrozoan jellyfish, is the best-known freshwater example. It has a diameter of less than an inch (2.5 cm), is colourless, and does not sting.

Some jellyfish populations have become confined to coastal saltwater lakes, such as Palau’s Jellyfish Lake. Millions of golden jellyfish (Mastigias spp.) travel horizontally over Jellyfish Lake on a regular basis.

12. Jellyfish are hosts to a wide variety of parasitic organisms

A diverse range of parasitic species lives in jellyfish. They serve as intermediate hosts for endoparasitic helminths, with infection passed to the final host fish following predation. Some digenean trematodes, particularly those in the family Lepocreadiidae, employ jellyfish as intermediate hosts. When fish consume contaminated jellyfish, they become infected with trematodes.

13. Jellyfish are also used as a food 

Jelly Fish. (9626832578).jpg , CC0, via Wikimedia Commons

In various places of the world, jellyfish have long been consumed. Fisheries have begun harvesting the American cannonball jellyfish, Stomolophus meleagris, for export to Asia along the United States’ southern Atlantic coast and in the Gulf of Mexico.

Humans consume jellyfish in several civilizations. Some Asian countries consider them a delicacy, and species in the Rhizostomae order are pressed and salted to remove excess water. According to Australian experts, they are a “perfect food” since they are sustainable, protein-rich, and low in food energy.

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14. Jellyfish are displayed in many public aquariums

Many public aquariums show jellyfish. The background of the tank is frequently blue, and the animals are illuminated by side lights, which increases the contrast between the animal and the background. Many jellies are so transparent in nature that they are practically undetectable.

Jellyfish are not accustomed to living in small areas. They rely on currents to carry them from one location to another. Professional exhibitions, like those at the Monterey Bay Aquarium, have precise water flows, usually in circular tanks to avoid trapping specimens in corners.

The outflow covers a huge surface area, and the inflow enters as a sheet of water in front of the outflow, preventing jellyfish from being drawn into it. Jellyfish were becoming popular in home aquariums in 2009, requiring similar equipment.

15. Some small fish are immune to attacks from the jellyfish

Jelly Fish (8113912393).jpg , CC0, via Wikimedia Commons

Some small fish are immune to jellyfish stings and reside amid the tentacles, acting as bait in a fish trap; they are protected from potential predators and can share the jellyfish’s catch. The cannonball jellyfish has a symbiotic relationship with ten different fish species, as well as the longnose spider crab, which dwells inside the bell and shares the jellyfish’s food while gnawing its tissues.

Finally, jellyfish, with their beautiful movements and ethereal beauty, remind us of the ocean’s treasures. Despite their mysterious character, they play an important role in marine ecosystems. Let us adore these enthralling creatures and work to defend their precarious existence, therefore assuring the survival of our magnificent aquatic world.

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