Jellyfish, also known as jellies and medusae, belong to the Cnidaria phylum, which has 11,000 species.There are 200 species of jellyfish. Out of this, Aurelia aurita, or moon jelly, is the most common jelly.These invertebrates feed on shrimp, fish, and small plants in the sea. Jellies use their tentacles to attack their prey. The transition from one stage to another in the lifecycle of jellyfish is mainly dependent on environmental conditions and seasonal changes. The three main stages in the lifecycle of jellyfish are the larva stage, polyp stage, and medusa stage. Bloom, swarm, and smac are the names given to a group of jellyfish. Jellyfish have nematocysts, a set of stinging cells. These cells help jellyfish by releasing venom when they sting. It also helps them to scare and capture food. The box jellyfish is the most dangerous jellyfish species in the world. Severe box jelly stings can be life-threatening as they affect the heart, triggering a heart attack in just a few minutes. Out of the 200 identified species, only 70 can cause serious harm to humans. They eat small plants, shrimp, or fish. Jellyfish have some natural predators like the ocean sunfish, gray triggerfish, turtles, seabirds like fulmars, whale sharks, hermit crabs, arrow crabs, and humpback whales. Some jellyfish species like the moon jelly (Aurelia aurita) can glow. Moon jelly and other jellyfish that glow have a special protein called the bioluminescent protein. Jellies can reproduce both sexually and asexually. Reproduction in these sea animals is triggered by a number of events, including food and light abundance.Continue reading to know more about the jellyfish lifecycle. Once you finish reading this article, you can also check out our other articles on what do jellyfish eat and do all jellyfish sting?What is a jellyfish’s lifecycle?The lifecycle of a jellyfish is quite complex. Some species reproduce sexually while others reproduce asexually. Throughout the lifecycle, jellyfish also go through different types of development and forms before they attain the final stage.The lifecycle of a jellyfish starts with mature male and female jellyfishes seeking companions, much like the lifecycle of any other animal. Mature jellyfishes, also called medusae, start mating when they come across a suitable match. Mating can occur at any time of day or night. Adult male jellyfish will release massive amounts of sperm into the water where the adult female has released her eggs. Once the free floating eggs are fertilized by the sperm, the eggs develop into small larva. The body of a planula resembles a flatworm with cilia, which are hair-like structures found throughout the body. A planula is nothing but a mass of cells. The planula becomes attached to a firm surface as it develops. The attached planula subsequently enters the next stage of its existence by becoming a stalked creature. Development is complete when the temperature is moderate and the availability of food is abundant. The jellyfish is known as a polyp.Polyps are also attached to a hard substrate. By the end of this stage, the polyp has built the jelly within its digestive tract and can fend for itself. This stage of a jellyfish’s life cycle is quickened when the polyp lengthens its body. It also develops segments in its body that will eventually split from the body to become an independent animal or separate polyps. This process of separating from the body to become individual animals or polyps is called strobilation. When the circumstances are right, the polyp begins duplicating itself to reproduce asexually. It is now recognized as a scyphistoma. The scyphistoma body gets thinner and has plainly discernible segments. The segments have gaps that are deep and aid in splitting the segments. Each segment now carries a whole set of muscles and digestive systems. All the independent segments of polyps are now called ephyra, and the segments are very tiny. Though the ephyra lacks bell-shaped stinging tentacles, it still resembles an adult jellyfish in many ways. Due to the absence of tentacles, it highly depends on the partially formed lobes on its bell to catch food and drive it towards its mouth.Once the ephyra matures, the bell, oral arms, and tentacles of the ephyra develop into specific shapes depending on the species of jellyfish. At this stage of the lifecycle of a jellyfish, it is called a medusa. The adult animal, despite being small, is able to reproduce. The sole goal of a medusa is to survive until it reproduces. This is why jellyfish generally do not live long at this stage. These stages repeat again.Do polyps become jellyfish?The lifecycle of a jellyfish has two main stages, the polyp phase and the medusa phase. The latter is a reproductive phase in which the eggs are fertilized when the sperm is ingested.The eggs grow into free swimming planula larvae. After swimming in the sea for a while, the larvae will settle on the sea bed. After settling, they become polyps. Some polyps will begin to start their life as juvenile jellyfish called ephyra larvae. This normally happens in spring. They develop into adult jellyfish when the conditions are ideal.There are two types of polyps, stalk polyps and sessile polyps. They are differentiated based on the shape. Adult jellyfish form stalk polyps, while a dozen or more juvenile jellyfish, or ephyra, can be produced by a single polyp.Each stage in the lifecycle of a jellyfish has its own function. Polyps play a huge role in maintaining jellyfish populations and ensuring long-term survival. They also play an important role in the formation of jellyfish blooms.What is a baby jellyfish called after the polyp stage?A baby jellyfish is called an ephyra after the polyp phase.Ephyrae occupy planktonic ranges. Eventually, they break off from the stalk that is fixed to a hard surface or strobila, after which they step into the next phase as free-swimming organisms. In the lifecycle of a jellyfish, the polyp stage is the second stage.This phase can last for several months or for a year. Some jellies can remain in the polyp phase for several years. A polyp comes from a jellyfish larva. The reproduction process is carried out in this stage.Did You Know…There are around 150 million jellyfish stings each year. There is a surge in the number of incidents because to jellyfish populations have been growing at explosive rates. Certain climatic changes and the warming of seas are favorable for jellyfish reproduction. It is believed that the population of jellies has increased by 65%. Scientists also suggest there could be more even jellyfish species in the sea. They suspect that there are at least 300,000 different species that have not yet been discovered.Jellyfish sting humans with their tentacles that have many stinging cells. Each cell contains venom that is activated when a human, or another animal, touches a jellyfish. Baby jellyfish are unable to sting you and it is only adult jellyfish that have the ability to sting.A species of jellyfish called the immortal jellyfish (Turritopsis dohrnii) directly forms polyps when the medusa is dead and settles on the ocean bed. Once it starts decaying instead of turning into a new medusa, it turns into polyps after which new jellyfish develop.Moon jelly (Aurelia aurita) males release sperm during the medusa stage in a trail which is swallowed by the female moon jelly and fertilized internally. Another interesting fact about the moon jelly (Aurelia aurita) is that despite having weak eyesight, it migrates when there are changes in the solar position.Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for jellyfish polyp then why not take a look at how long do jellyfish live, or jellyfish facts?
Jellyfish, also known as jellies and medusae, belong to the Cnidaria phylum, which has 11,000 species.
