Blue jellyfish (Catostylus mosaicus) are of the order Rhizostomae. These jellies originate from the Indo-Pacific region of Asiato Australia. They are most often found in large swarms. Their swarms are in fact so large that they are considered a nuisance by Australian fishermen because they can fill whole nets. They wreaked havoc with power plants and blocked ship entrances.
Blue jellyfish do not have the long trailing tentacles most commonly associated with jellyfish. Instead, they have eight extruded mouth arms right under their bell forming a circular pattern. Each of these mouth arms has thousands of small mouths as opposed to a single mouth opening. Although blue jellies have eight buccal arms, other related species of this order only have three or four.
Blue jellies are among the jellyfish species that do not depend entirely on external s for their nutritional needs. A large part of their nutritional contribution is signified by the symbiotic relationship they maintain with the unicellular algae that live there. The body of the jellyfish shelters these algae. In return, part of the photosynthetic process of algae provides nutrients rich in carbon to their host.
The unique appearance of blue jelly makes it one of the most exotic jelly specimens currently available to amateur aquarists. They have become increasingly popular as pets in the Eastern Hemisphere due to their almost “otherworldly” appearance and their abundance. Unlike lunar jellyfish, blue jellies are translucent rather than transparent. They do not have this strange and floating ghost appearance when the light passes through them. They are however just as amazing under an LED fader. The combination of their globular shape, their way of swimming, their pearly reflection and the colored light passing through their semi-transparent bodies makes them look like the globules of a lava lamp. They also look great under T5 and actinic lighting. They come in a variety of colors, including white, red, blue, purple and yellow with contrasting accent hues.
You have to understand that blue jellyfish have a symbiotic relationship with the algae that grow inside and depend on them for a vital part of their nutritional needs. If you intend to try to keep them as pets, they will need an aquarium lamp similar to that of a coral reef tank. This will help them stay alive and healthy.
Blue jellyfish use night hunting to meet their nutritional needs. The size of the mouth openings on their mouth arms limits what they can consume. They feed mainly on zooplankton from the lower levels of their habitat. Blue jelly injects venom into this zooplankton which kills or paralyzes them, thus making them immobile to facilitate their consumption. This venom is not toxic enough to be seen by most humans. However, just like a bee sting, some people are more sensitive to this toxin and may experience a rash or even an allergic reaction.
Blue jellyfish have a symbiotic relationship with the algae that grow there and depend on them for a vital part of their nutritional needs. If you intend to try to keep them as pets, they will need an aquarium lamp similar to that of a coral reef tank. This will help them stay alive and healthy.
They very often come small, but can grow anywhere from 12 to 18 inches in diameter. Like many jellyfish, a sudden decrease in size is a sure sign that they are not getting enough to eat. Their lifespan is one year in the wild. We found no information to indicate that captive life will cancel their natural life cycle and extend their longevity in domestic aquariums. Blue jellyfish live in tropical to temperate zones. In captivity, a temperature range between 75 and 78 F is considered ideal.
by Stephen J Broy