A living lava lamp, someone calls these drifting hordes of glowy, gelatinous bulbs. But you can just call them what they are - jellyfish.
They range from the northern sea nettle, with its lethal-looking tentacles, to the placid-looking moon jellies.
They’re not much beyond a stomach and reproductive organs. The ones with the classic dangly arms have the painful tentacles on the outside, laden with the stinging cells called nematocysts that shoot tiny harpoons at their prey. In the middle are the oral arms, long frilly appendages that draw the food up to the mouth.
Water in aquarium tanks is constantly cycled through a filtration system, with a screen to keep critters from getting sucked in. But, for a jellyfish, a screen is a calamity. They’re kept in round or oval tanks with a circular current that pushes them past the screen at an angle; while water leaves to be cleaned, the jellies flow on, their parts intact.
Keeping jellyfish is not for the faint of heart. There’s the special tank. The live food. And, periodically, you have to take all the jellyfish out and bleach the tank to kill the pesky little hydroids that hitchhike in, sting the jellies, and steal their food.
Well, in my book, that is exactly what justice is - they who sting will get stung! The food stealing thing is just a bonus (also kind of justice-doer’s reward)