We don't call them jellyfish anymore, because they're really not fish at all. Jellies are weird, gelatinous animals. They are found in all of the world’s great seas and some are even found in fresh water.
Jellies are incredibly complicated, diverse creatures. Just ask our "jelly guy", Krish Lewis: "Some jellies prefer warm water, others cold water. Certain species need strong light as they have symbiotic algae. Others want a specific amount of salts in the water. Some are cannibals and need other jellies as a major part of their diet."
Jelly venom is unique in the natural world. It is very different from most of the venoms that we are familiar with. It actually works exactly like the lethal injection. The venom floods the prey’s cells with potassium, causing the cells to short circuit. It's one of the only known naturally occurring venoms that stop the heart of its prey in a contracted state. So saying that “a jelly shocks you” when you are stung is technically correct.
Krish says that running the Jelly Gallery takes a lot of planning and preparation. Animals need to be grown out months in advance if they are going to be a decent size and look like a jelly!
Our jellies are housed and grown in cylinders or kriesels. A kriesel is a jelly tank shaped like a tumble dryer. It allows the jellies to float in the tank with a gentle current, and not left to lie pulsing on the floor. The flow of water must be just right, keeping animals suspended instead of being knocked around, sucked in or damaged by pumps and overflow screens.
Every time a jelly pulses, it eats. It wisps food around its bell and through its curtain of tentacles. With the next pulse, the food that gets stung is flicked onto its oral arms or lips. The lips then carry the food into the central mouth. Jellies like upside downs and blue blubbers have thousands of tiny mouths on their oral arms that lead to a central gut.
Because jellies are constantly eating, they are constantly growing. When jellies don’t eat, they simply shrink, but can eat again to regain their lost body weight or regrow damaged body parts.
We can compare the jelly life cycle to that of the butterfly’s. Butterflies are caterpillars, which turn into pupa, which then later emerge as butterflies. Similarly, the jelly has polyps that transform into strobula, which bud off ephyrae (baby jellies), which then mature into jellies.