The jellyfish that looks like breakfast
It lives in partnership with algae and may benefit from the warming of the sea, but most interestingly – does the fried egg jellyfish sting? Living in the moment – the hot questions about the most interesting animals.
In a sea of jellyfish, there is one that manages to evoke a smile and wonder in everyone who encounters it. The "fried egg" jellyfish is undoubtedly one of the most spectacular and photogenic creations in our marine space. It shares its life with symbiotic algae, has a mysterious life cycle, and a digestive system much more sophisticated than previously thought. To deeply understand the world of these jellyfish, we spoke with Prof. Dror Angel from the Leon Recanati Institute for Maritime Studies and the Department of Maritime Civilizations at the University of Haifa, and CEO of the "Jellyfish in the People" association, who has been researching gelatinous creatures for decades and trying to decipher their secrets.
Let's start with the most obvious question: why is it called a fried egg jellyfish?
"The common name 'fried egg jellyfish' comes from its unique appearance. When you look at it from above, there is a dark yellow-orange bulge in the center that looks exactly like a yolk, and around it are white edges that complete the look of the egg white. Its scientific name is Cotylorhiza tuberculata, and it is common in the central and western Mediterranean Sea. Here in the eastern Mediterranean lives a relative of hers that looks slightly different - it is less colorful and its scientific name is Cotylorhiza erythraea".
And the question that occupies every bather in the sea: does it sting?
"All jellyfish belong to the phylum Cnidaria and have stinging cells designed to neutralize their prey. However, not every jellyfish stings us with the same degree of pain. The venom of the fried egg jellyfish is intended for small creatures, and most humans are not sensitive to it at all. It is important to understand that the sting we feel when encountering a jellyfish in the sea is not because the jellyfish wants to sting us, but as a result of contact with its hunting tentacles. Moreover, the fried egg jellyfish usually does not create huge swarms like the swarms of the nomad jellyfish species that we are all familiar with. The fried egg jellyfish appears as individual specimens or in small groups, and it is considered much less annoying to the public".
Who feeds on fried egg jellyfish, and what do they eat?
"Fried egg jellyfish, like other species of jellyfish, serve as food for a huge variety of animals such as turtles, fish, and birds. Jellyfish in general are an integral part of the marine food web, and in some places in the world, humans also enjoy eating different species of jellyfish. Fried egg jellyfish prey on various types of plankton such as tiny crustaceans and thus compete for food with young fish".
However, according to Angel, not all of this jellyfish's diet is based on predation:
"One of its most fascinating characteristics is that, similar to corals, symbiotic algae live within its tissues. The jellyfish provides the algae with protection and shelter, and the algae perform photosynthesis and provide the jellyfish with organic food. Because of the dependence on sunlight for the photosynthesis process, we will find fried egg jellyfish mainly in shallow water. This is critical for them - without the symbiotic algae, these jellyfish will not be able to complete their life cycle and produce new jellyfish".
What does a jellyfish's life cycle look like?
"Adult jellyfish release germ cells into the water. After fertilization, tiny larvae are formed, which look for a place to settle on the bottom. There they become 'polyps' - sedentary creatures that look like tiny sea anemones and can live like this for months and even years. Each polyp must obtain the symbiotic algae from the water around it to move to the next stage in the life cycle".
"When environmental conditions are suitable, the polyps that have algae in them undergo a process called 'strobilation'. In this process, they create many tiny discs that are released into the water as miniature jellyfish that grow until the adult jellyfish stage".
How does the climate crisis affect the fried egg jellyfish?
"In general, fried egg jellyfish like warm and salty water, so it seems that they may 'benefit' from the warming of the water. However, there is a catch here. If temperatures reach extreme conditions for a long time, it could harm their symbiotic algae. Similar to 'coral bleaching', when sea water gets very hot, the jellyfish may lose its algae, which could cause it to stop growing and even die. Therefore, moderate warming may help them, but extreme heat waves are a real threat".
Finally, what should we do when we meet a fried egg jellyfish or any jellyfish in the sea?
"The most important message is to respect them. Do not treat them as a nuisance or as something negative. If you see a jellyfish, just give it its space and enjoy its beauty and mesmerizing movement. Swimming and diving alongside these gelatinous creatures is a magical experience. The sea is a wonderful world of shapes and colors, and the fried egg jellyfish is one of its most charming ambassadors".
