The Moon Jellyfish are found in the tropical waters of the ocean and are known for their beautiful appearance. Also called ‘saucer jellyfish’, it isn’t yet fully understood by the scientists as to how long these jellyfish have been on the earth. These invertebrates are bioluminescent (glow in the dark) and a favorite item in the aquarium pet trade. In some highly populated tourist beaches, they are found in large numbers, while measures have been taken to limit their populations.
Moon Jellyfish Scientific Classification
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Size: They are typically between 25 and 40 cm (10–16 inches) in diameter.
Body: The body is translucent, with almost all the internal parts visible from the top. These creatures can be recognized by their four characteristic horseshoe-shaped gonads, having a faint purple hue. Younger individuals often have patterns of spots and streaks.
Sexual Dimorphism: Both the sexes look alike.
The creatures have several subspecies; however, they look so much alike that it is practically impossible to differentiate between them without taking their DNA samples.
Lifespan/Longevity: How Long do Moon Jellyfish Live
The moon jellyfish will live for about a year (both in the wild and in captivity/marine tanks).
Distribution/Range & Habitat: Where do Moon Jellyfish Live
They are mostly found in the warm and tropical waters around the world near the coasts of the Atlantic, Pacific, and the Indian oceans. However, they are more common in the Monterey Bay along the coast of California, and in the open waters close to the East Coast, Japan, Gulf of Mexico, and Europe.
Like most other jellyfish species, the moon jellyfish move around horizontally, swimming by pulsation of the bell-shaped upper part that always stays close to the water surface. This behavior let them keep their tentacles spread over a larger area and help them capture food at ease. They sometimes migrate in small groups in search of food.
A group of jellyfish is termed as ‘smack’, and when several smacks gather together to form a larger group, it is called a ‘bloom’. A single bloom may consist of more than a thousand individuals. However, the formation of bloom depends on several factors, including the water’s oxygen content, ocean currents, nutrients, and temperature. These creatures invade their prey by using their stings and injecting nematocysts present in their tentacles.
Diet: What Do Moon Jellyfish Eat
The moon jellyfish are carnivorous and primarily live on planktons including organisms like crustaceans, tunicate, mollusks, young polychaetes, protozoans, fish eggs, larvae, rotifers, diatoms, and other small jellies.
Mating and Reproduction
The breeding season of the moon jellyfish is during spring and summer. They are oviparous, while the eggs mature in the female jellyfish’s gonads that are the most recognizable part of these creatures since they are brightly colored. These organs are placed inside the pockets that are formed by the oral arms’ frills and are positioned at the bottom of their stomachs. The eggs get fertilized after the female ingests strands of floating sperm released by the male jellyfish.
As the eggs get fertilized, they are released by the female, which eventually transform into larval forms called the ‘planula’. These newly-developed creatures float on the water surface until they find a hard surface to cling to, and finally turn into a polyp.
When the conditions are favorable, the polyp divides, and the tiny jellyfish swim away individually. At this stage, they are called the ‘ephyra’. It is from this stage that the baby jellyfish metamorphose into adults.
Adaptations for Survival
- Their almost transparent body makes them less visible to predators.
- The oral arms of the moon jellyfish have tentacles that carry stinging cells called ‘nematocysts’, which can stun their prey, as also, ward off their predators.
- Their body is radially symmetrical, which helps them find food in any direction.
Their primary enemies are the other larger jellyfish, and big-sized open water creatures including the ocean sunfish, spadefish, tuna, swordfish, and the leatherback turtle.
Do Moon Jellyfish Sting (Are they Poisonous/Dangerous)
The tentacles of this vertebrate are poisonous to some extent, but only to the small marine creatures. They are practically harmless to humans. People are not affected by their poisonous bites since the venom (toxin) does not penetrate human skin.
The IUCN has enlisted them under their ‘Not Evaluated’ category.
- Their body lacks digestive, circulatory, respiratory systems, and even, backbone, brain, blood, ears, eyes, or heart.
- They have only one multi-purpose opening, situated between the oral arms, which acts as the mouth, anus, as well as an entrance for sperm the in females.
- The body of these creatures is made up of 95% water, 3% protein, and 1% mineral.
- They are a close relative to the infamous Portuguese man-of-war jellyfish.
- The jellyfish is edible and is considered a delicacy, especially in a few Asian countries.
- The jellyfish got its name from the whitish-translucent moonlike circular bell, roughly resembling the full moon from the top.