How Many Babies Can Jellyfish Have at a Time

When yous think of a jellyfish, you are probably picturing a translucent, bell-shaped animate being with long flowing tentacles. While iconic, that's only a short stage of a jelly's life - the "medusa" phase of a true scyphozoan jellyfish before information technology dies. Jellyfish live far longer, more interesting lives than you may have imagined!

Let'south take a look at the incredible life cycle of jellyfish; for consistency, we're going to exist using images of Aureliamoon jellies as much as possible:

Life begins - the egg

The life story of a jelly begins just like ours - with a male and a female looking for a chance to mate. At dusk or dawn, adult jellies, known as medusae, assemble in large numbers to spawn. This means that they release huge amounts of sperm and unfertilised eggs into the ocean around them. These spawning events continue throughout the lives of the developed jellies and are triggered by their proximity to other jellies, calorie-free and nutrient abundance. The larger an adult jelly can grow in this time, the more offspring it may be able to take.

The fertilised eggs are commonly left to drift freely in the ocean currents, but some jellies make more of an effort to protect their eggs. For case, moon jellies allow the fertilised eggs to attach to their oral artillery and protect them until they are prepare to survive the next phase of their lives...

Some species are a bit more careful with their gametes. These box jellies are mating - the male pulls the female close with his tentacles, ready to laissez passer his sperm package to her. Prototype courtesy of Alvaro E. Migotto / NOAA.

Jelly babies - planula larva

The egg grows into a small larva called a planula. This planula can swim freely and resembles a microscopic flatworm, covered in tiny hairs called cilia. These cilia crush rhythmically and allow the planula to swim about. The planula continues to grow and when information technology is sufficiently large it tries to find a suitable solid surface to adhere itself to.

This microscopic mass of cells is a planula, the larval stage of a moon jelly that is free-swimming and trying to find the perfect habitat on the seafloor. Adapted from original of Thomas Schwaha [CC BY 4.0]

In most cases, the planula finds a piece of solid seabed to attach to, with different species preferring different types of terrain. In some cases, they may even attach themselves to other animals, especially the bodies of other adult jellyfish. Once a perfect spot has been constitute, the planula enters the adjacent phase...

The long babyhood - polyps

The fastened planula develops into its side by side life phase - the polyp. Polyps tin can be idea of as small stalked animals with one end fixed to the ground, and the other stop extending into the water with a ring of tentacles surrounding its mouth/anus. In this phase, the jelly has a fully developed digestive system and is able to catch prey and feed itself efficiently.

You tin can see jellyfish polyps for yourself at the Aquarium'south recently upgraded Microscope Exhibit.

In the polyp stage, the jelly closely resembles its cousins, the sea anemones. © Two Oceans Aquarium

This jellyfish polyp very closely resembles other marine animals - hydroids, anemones and corals. In fact, these animals are very close relatives of true jellyfish and would have followed the same lifecycle upward to this point. The difference is that a jellyfish will develop into new stages beyond the polyp, while an creature like an anemone will essentially become an "adult polyp".

As the polyp grows, it begins to segment and create clones of itself. The polyp on the left is at the showtime of this stage of its life, but has not yet lost its tentacles. © Two Oceans Aquarium

Depending on the species, the jelly tin can remain in this polyp stage for years. This allows the jelly to wait for perfect conditions to mature when atmospheric condition are suitable or large numbers of their species to spawn earlier moving onto their final adult form.

© Ii Oceans Aquarium

Budding teenagers - scyphistoma

When atmospheric condition are platonic, the polyp begins to reproduce asexually, past cloning itself. The polyp elongates and forms segments which will eventually bud off to class contained animals or even more polyps to speed upwards this process. This process is known as strobilation, and the strobilating polyp is called a scyphistoma.

The scyphistoma of a moon jelly - this polyp has substantially become a stack of tiny juvenile jellyfish clones, ready to be released into the ocean. Adapted from original of Circa24 [CC Past-SA 3.0]

The procedure of strobilation begins with the polyp's tentacles being reabsorbed into its body. The polyp's trunk becomes narrower and clearly visible segments begin to form.

Somewhen, the grooves betwixt these segments become deep enough for the segments to separate entirely, taking a fully contained fix of muscles, nerves and digestive system with it...

Finding themselves - ephyra

The tiny, newly-budded segment of polyp becomes a free-living organism known as an ephyra, which is the forerunner of the adult jelly. At this phase, the ephyra is no more than a few millimetres beyond, simply as it swims away, it feeds and grows. The ephyra does not have the closed bell-shape and stinging tentacles of an developed jellyfish, and has to rely on the undeveloped lobes of its bell to push button food towards its mouth.

An ephyra of an upside-down jellyfish bred at the Aquarium. © Two Oceans Aquarium

What's of import to keep in mind is that, although this jellyfish has entered a new phase of its life, information technology is just one of many clones. It is entirely possible that the original polyp and copies of that polyp are still alive and may even outlive this new jelly.

The ephyra of a moon jelly under the microscope. Information technology may await fragile, only this organism is equipped with everything it needs to grow into a mature adult. Adapted from original of Circa24 [CC BY-SA 3.0]

See a world of jellies on your next visit to the Two Oceans Aquarium.

As it grows, the ephyra begins to more than closely resemble its adult stage. © Homebrew Films

Frisky, hungry adults - medusa

As the ephyra grows, its bell takes on the characteristic shape and its tentacles and oral arms will grow into the forms unique to its species. This adult form is called the medusa.

The developed, medusa stage of the jelly's life is what nigh people would recognise as a "jellyfish". Still, this is only a very small part of the animal's life. © Two Oceans Aquarium

Although the initial adult is small, it is already a mature animal and capable of reproducing - merely there are a lot of incentives to grow equally large as possible every bit quickly as possible, for instance:

• Jellies, similar moon jellies or compass jellies, gather in huge numbers to spawn. To be reproductively successful, a jelly needs to produce more sperm or eggs than its rivals - and that means beingness a bigger jelly.
• Abyssal dwelling jellies are fewer and far betwixt, so their incentive for growing large quickly is to deter predators to that they can survive long enough to reproduce.
• Some jellies, like Southward Africa's pink meanie, rely on very specific conditions (in the case of the pinkish meanie, it needs other types of jellies to flower in big numbers). Because those conditions might exist unusual or brusque-lived, the jelly needs to grow from polyp to medusa every bit fast as possible to take reward of them.

Deep-sea jelly species, like the Deepstaria, are non abundant enough to be able to rely on huge blooms to observe a mate. It is these species that must rely on long adult lifespans, immortality and other unusual jelly tactics in order to reproduce. Image courtesy of EVNautilusLive/YouTube (sentry the video - it'due south astonishing)

As this point, you might be wondering "If the jelly clones itself then goes off to reproduce sexually, how does information technology avoid mating with itself?" Good question - to avoid this almost all jellyfish species have discrete sexes, i.e. the original egg and all its future clones volition exist either male person or female. Hermaphroditism merely occurs in rare species - and is usually a survival tactic for jellies that never occur in large enough numbers to exist guaranteed finding a mate in any given generation.

Moon jelly medusae at the Two Oceans Aquarium. The crescent moon-shaped bodies almost their centre are their gonads, ready to seed the next generation of jellies. © Two Oceans Aquarium

Death (but not actually)

The purpose of the medusa is merely to alive long enough to reproduce, and typically jellyfish do not live very long in this phase. Many of the jellies we get at the Aquarium live for no more than than a few months before essentially reaching their "quondam historic period". As you lot have hopefully come to realise by this betoken, the medusa does not represent the full life of the jelly, just the finish of it.

As they age, jellies put increasingly more resources into producing eggs or sperm. This comes at the cost of their immune systems, resulting in older jellies being more than susceptible to infections. This old compass jelly at the Aquarium has a condition called "bell rot" a bacterial infection of its bell (note the missing lower section), an almost inevitable fate for jellies in their quondam-age. © Two Oceans Aquarium

Jellies are exceptionally good at identifying the perfect weather to reproduce in, so they do not need unnecessarily long lives. If the conditions are practiced for it to become an adult medusa, it will likely exist able to spawn the next generation rapidly and efficiently likewise.

You may have heard of jelly fish blooms occuring equally a result of overfishing or climate change - this is an example of how finer and rapidly jellies tin reproduce when conditions are ideal for them.

Information technology'south possible that you may have seen stories of an "immortal" jellyfish, i that can theoretically alive forever because its adult medusa can revert dorsum to be polyp stage. This is true - but it's not the only jelly that has beaten death. Think, when the adult medusae of about jellies are dying of former age, clones of their polyps are still thriving on the seafloor. Through cloning, most jellies can theoretically live uncommonly long lives.

So, what did we learn? Jellies are awesome biological cloning machines, masters of efficiency, possibly immortal, and undeniably awesome.

Be sure to visit the jellyfish in our Jelly Gallery on your next Two Oceans Aquarium visit.

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Source: https://www.aquarium.co.za/blog/entry/jellyfish-life-cycle

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