The Regal ‘Crown Jellyfish’

Learning more about the elusive ‘Cephea cephea’

Your Majesty…

The crown jellyfish is a gorgeous jellyfish indeed! It pulses along majestically through the ocean waters, stunning all in its wake! Such a beautiful jellyfish is truly a sight to behold. The jellyfish sports a royal purple bell, surrounded by a superb frilled bell. At the top of their bell, they have 30 appendages that stick out, but scientists are still baffled by what these could be for.  Due to the rare nature of these jellyfish, very little is known about them. What we do know though is valuable, precious information.

The jellyfish is of an average size, as far as scientists can tell. Their tentacles have been recorded to reach lengths of 80 centimeters, or 31.5 inches in length, but it is unknown if this is the maximum length. However, the stunning bell of these jellyfish can reach  a whopping diameter of 60 centimeters! That’s 23.6 inches, which is well over a foot!

The Monarch’s Life

The crown jellyfish rules the deeper indo-pacific and atlantic ocean’s waters, living at a depth of 200m-1000m (in the Twilight Zone) below the surface. They are most often found in the depths at an average of 700m deep. The waters are dark, and cold, meaning these jellyfish typically live at a temperature of around 7° Celcius. Because they live in almost total darkness, this jellyfish has actually adapted to shine bioluminescent lights! They use these bioluminescent lights to lure in prey, and distract predators alike.

Like most jellyfish, they feast daily on zooplankton. In the Monterey Bay aquariums, they’ve also been known to take readily to brine shrimp. They easily catch their prey with some of the most powerful venom known to jellyfish. Ironically though, they seem to have no impact on most living life. They are completely harmless to humans. In fact, in east asian countries, they are seen as a delicacy. The sting of these jellyfish is so weak that they are unable to do so much as spook a small fish. In fact, they’ve even been found to host various species of fish in the safety of their bells. Below is an example of such a phenomena.

The life cycle of this jellyfish mimics most other jellyfish. However, what is fascinating is the speed at which they grow! The Monterey Bay aquarium has stated, “our aquarists found the species to grow at an extremely fast rate — from just a few millimeters to the size of a dime in two to three weeks” ( The speed at which these jellyfish grow could also play a large part as to why they have such short life cycles. In fact, these jellyfish are known to live only up to six months in the wild. It is unknown for how long these beautiful jellyfish live in captivity.

Can You Keep a Crown Jellyfish?

As of yet, the answer is no. Not in our small aquariums that we sell. Jellyfish Aquarium currently does not have enough information on this species to be able to confidently stock these jellyfish for the public. Of course, as much as I would love to keep one, it’s necessary to develop bigger and better aquariums for these jellyfish. Not only that, but finding cheaper and more available water cooling systems to regulate the temperature is a must.

One day, in the future, it may be possible to keep a crown jellyfish in our own homes. But for now, we can admire this jellyfish from a distance.


If you’d like to learn more about the crown jellyfish, please take a look at some of the links below that were used to write this article!