About
Jellyfish are invertebrates that, together with corals, gorgonians and anemones belong to a group called the cnidarians (knidé = nettle, from the Greek). This animal group has stinging cells which they use both to capture their prey and as a form of defense. These cells contain a capsule with a rolled-up filament and a poison. When a prey animal makes contact with the jellyfish, the capsule opens and the filaments are ejected and stick onto the prey, injecting their poison.
Jellyfish are pelagic animals they live in the open seas from tropical to Artic waters and, although they can propel themselves with rhythmic motions of their umbrella, they are basically at the mercy of the currents of the sea.
Because their body is 95% water, they are perfectly camouflaged. The body of a jellyfish exhibits radial symmetry and is divided into three main parts: the umbrella, the oral arms (around the mouth) and the stinging tentacles. They have an internal cavity, in which digestion is carried out. This cavity has a single aperture which functions both the mouth and the anus.
Food
Jellyfish are carnivores and can increase in size rapidly and procreate in large numbers 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, and in some cases, small fish and other jellyfish also form part of their diet. It is a strange sight to see the jellyfish’s latest prey inside its body before it is digested.
Reproduction
In order to reproduce, males and female jellyfish release sperm and eggs into the water (sexual reproduction). After fertilization, they develop larvae which give rise to new jellyfish or polyps that settle on the sea floor. From these polyps, by means of asexual reproduction, new free-living jellyfish may develop.
Defenses
The tentacles, with their stinging cells, serve as defense 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 and release a toxic substance that paralyses the prey. The oral arms help in the capture and ingestion of the captured animal.
Natural Predators
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 such as anemones, certain nudibranches (small molluscs without shells) also feed on jellyfish. Some of these may even take over their stinging cells to use in their own defense.
FAQs
Jellyfish have no brain, heart, bones or eyes. They are made up of a smooth, bag-like body and tentacles armed with tiny, stinging cells. These incredible invertebrates use their stinging tentacles to stun or paralyse prey before gobbling it up. The jellyfish's mouth is found in the centre of its body.
What are 5 facts about jellyfish? ›
10 Amazing Jellyfish Facts for Kids
- Some jellyfish can glow in the dark. ...
- Jellyfish are the oldest multi-organ animal. ...
- Jellyfish are found all over the world. ...
- Some jellyfish are immortal. ...
- Not all jellyfish have tentacles. ...
- There's a giant jellyfish called the hair jelly. ...
- 150 million people are stung by jellyfish each year.
Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are anchored to the seabed by stalks rather than being mobile. The bell can pulsate to provide propulsion for efficient locomotion.
What special features do jellyfish tentacles have? ›
The tentacles, with their stinging cells, serve as defense 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 and release a toxic substance that paralyses the prey.
What is the special ability of jellyfish? ›
Jellyfish can time travel
Prior to that is the polyp phase, and Turritopsis nutricula species has been nicknamed the 'immortal jellyfish' due to its ability to travel backwards to the polyp phase during times of stress.
What are 3 characteristics of a jellyfish? ›
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.
Why are jellyfish so special? ›
Jellyfish are a profoundly powerful symbol for the declining health of our world's oceans. They are known as an indicator species, meaning changes in their populations represent greater changes in the ecosystem. Around the world today, jellyfish are thriving in record numbers.
What best describes a jellyfish? ›
Jellyfish have no brain, heart, bones or eyes. They are made up of a smooth, bag-like body and tentacles armed with tiny, stinging cells. These incredible invertebrates use their stinging tentacles to stun or paralyse prey before gobbling it up. The jellyfish's mouth is found in the centre of its body.
How long do jellyfish live? ›
Like any fish, the ideal conditions to keep them in will mimic their natural environment in the wild. Jellyfish live around one year to a year-and-a-half in the wild. In captivity, its usually 6 months to a year, largely because of the difficulty replicating the drifting currents and space offered by the open sea.
Do jellyfish have teeth? ›
Some species of jellyfish do have eyes and "teeth," or rather thin hairs that pull in and bite down on their food.
Jellyfish are more advanced than once thought. A new study from the University of Copenhagen has demonstrated that Caribbean box jellyfish can learn at a much more complex level than ever imagined – despite only having one thousand nerve cells and no centralized brain.
What are jellyfish good for? ›
Jellyfish contain antioxidants that combat free radicals, reducing oxidative stress and potentially lowering the risk of chronic diseases. These potent antioxidants play a pivotal role in fortifying overall health by bolstering immune function and curbing inflammation, offering a holistic approach to well-being.
What skills do jellyfish have? ›
Scientists demonstrated that the jellies could acquire the ability to avoid obstacles through associative learning, a process through which organisms form mental connections between sensory stimulations and behaviors.
What is the secret about jellyfish? ›
Jellyfish have no brains, hearts, or bones and yet, they have the ability to stun and kill prey with a sting from their tentacles. The alien-looking creatures have odd anatomy such as the ability to eat, get rid of waste, and shoot a jet of water from the same orifice.
What are the unique behaviors of jellyfish? ›
Their behaviours include swimming up in response to somatosensory stimulation, swimming down in response to low salinity, diving in response to turbulence, avoiding rock walls, forming aggregations, and horizontal directional swimming.
What are 5 things jellyfish eat? ›
Jellyfish are carnivores, so their diet mainly consists of other animals. This includes zooplankton, small crustaceans, small fish and other jellyfish, according to Oceana, an ocean conservation nonprofit. Jellyfish will also consume plants, National Geographic reports.
What are 100 interesting facts about jellyfish for kids? ›
- Some jellyfish trap their prey, while others trawl.
- They Aren't Really Fish.
- In China, they are considered a delicacy, and are also used in Chinese medicine.
- They don't have brains, hearts, or lungs.
- Some jellyfish are clear, but others are vibrant colors of pink, yellow, blue and purple.
Oklahoma Aquarium 的帖子
- Moon jellyfish are named after the shape and color. ...
- Moon jellyfish can grow up to 16 inches in diameter. ...
- The colors displayed in the moon jellyfish's bell can. ...
- Moon jellyfish live in tropical and subtropical oceans. ...
- Moon jellyfish can sting, but the sting is very mild.
Basically, creating younger versions of itself that will become identical to its mature adult form when grown. A jellyfish fountain of youth! Yet, other species aren't so lucky. Most jellyfish only live for about a year, with some only living for a couple of days.
