The crown jellyfish Periphylla periphylla
- Runar Bolstad
- Jul 14, 2024
- 3 min read
Updated: Jul 15, 2024
In search of the beautiful crown jellyfish Periphylla periphylla on the west coast of Norway. I was invited along in search of this beautiful creature by one of the world's best nature photographers. My role was to be the boat driver and make it possible for him to be able to take his film clips for his project. In return, I got to do the same dives as him.
Blackwater dives is what it's called when you dive in the free water column and when you can't see the bottom and when it's so far to the bottom that you can't dive there. In addition, such dives are usually carried out from a boat and preferably far from land.
New pictures 15. july 2024 15:05
300 meters deep
The plan was a night dive in the middle of the fjord in the area, Lurefjord in Norway, where the jellyfish come to the surface in the dark to catch food. But there was some unfavorable weather and waves. There was also power and poor visibility. It is therefore important that the boat driver keeps his eyes open at all times and keeps a close eye on both bubbles and surroundings.
After loading all the equipment into the boat and driving where we were going, it was time to sit with our face over the reef and check if we saw jellyfish. And quite rightly so. Large numbers of jellyfish in the same place every time.
So then it was just a matter of getting into the equipment and jumping overboard. Did I write that it was 300 meters deep? Yes, then you must trust the boat operator and your own abilities as a diver. I was ready, had tested the camera, put on a wide-angle lens and adjusted the strobes the way I wanted them. Now all we had to do was "off we go".
Poor visibility and hundreds of jellyfish
Already in the first meter below, I spotted the jellyfishes. God, there were a lot of them. But there was poor visibility and a lot of particles and "stuff" in the sea. So I realized that there where small margins if I didn't want too much backscatter in the picture. And I shot pictures, lots of pictures. And also lots of bad pictures. Here it was all about working quickly, being precise with lights and strobes and diving with a itchy trigger finger. I probably snapped 300 pictures pr. dive. But there are incredibly small margins for getting good pictures without the milky background and all the small amphipods and particles in the water.
For those who dosnt know. Backscatter is when the flash light hits particles in the water, which then reflect the light back in to the the lens.
In projects > jellyfish > perifylla perifylla you will find more pictures as I upload them.
Cold and happy
We returned to shore about 4AM very cold and happy after doing 2 hours under water each. I got what I came for. Now I needed to check all the images and hope that at least some of them where usable.
Relevant information about the crown jellyfish Perifylla perifylla
Brief summary of information about Perifylla perifylla. I have collected and freely reproduced what I have found out so that you don't have to look any further.
Sorces for information
Sources are artsdatabanken.no , forsking.no , nrk.no and wikipedia.no .
Description
Periphylla periphylla, also known as the "crown jellyfish", "helmet jellyfish" or "merchant-cap" is a reddish luminescent jellyfish that lives in the depths of the sea in all the world's oceans with the exception of the Arctic.
It belongs to the order Coronatae within the order Cnidaria.
Periphylla periphylla is the only species in the genus Periphylla and is a rare example of a jellyfish that lacks a polyp phase in its life cycle.
Jellyfish have no heart or brain and do not hunt in what we normally think of as hunting. Why or exactly how evolution has caused them to rise to shallower water to find food, then go deep again before it gets dark is not known.
Like other ringed jellyfish, the crown jellyfish has a clearly deeply lobed edge on the bell. The tentacles sit in the notches between the lobes and are stiff and thick, usually there are 12 of them. It is reddish in colour, an adaptation to life in deep water. The red color is due to porphyrin , which is inedible for most animal species. The bell itself is relatively tall and conical, and emits bioluminescence , possibly as a warning of its porphyrin content.
Habitat and distribution
It lives at depths of up to 2,700 meters and is adapted to the dark environment.
The crown jellyfish is also found in very cloudy and milky water.
It avoids sunlight which is very harmful to it. especially dangerous for younger individuals. They are therefore active within reach of divers at night.
In some places in Norway, they appear in large numbers. In the Lurefjord in Western Norway, large numbers of them come up at night in search of food.
The crown jellyfish is a top predator and has no natural enemies that we know of.
Why there are so many of them in Lurefjorden is not known. But they thrive very well in very turbid water, moreover, they are trapped inside the fjord.
Bioluminescence and photophobia
The crown jellyfish lights up using bioluminescence, and the red flashes act as signals between the individuals.
It has small sensory buds between the marginal lobes, which help it distinguish between light and dark.
Because of its photophobia, it avoids light and therefore lives in deeper parts of the ocean.
Size and weight
The helmet jellyfish can be up to 30 cm long and weighs an average of 540 grams.
It consists mainly of water, with the rest of the body consisting of tissue and jelly-like mass.
Image/Illustration
Tentacles and swimming patterns
The crown jellyfish has twelve tentacles, and each individual can have different tentacle positions.
The most common positions are straight extended tentacles with an angle of 45 degrees to the axis of the body, or straight extended tentacles with an angle of 45 to 90 degrees.
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