knowledgeablevegan this tank looks extreme crowded?? i dont know much about jellyfish but wikipedia says “Jellyfish are not adapted to closed spaces. They depend on currents to transport them from place to place.”

These jellyfish are moon jellyfish (I think). They are being kept in a tank that is safe for them. The kreisel tank is specifically designed to meet the needs of jellyfish. It mimics currents without putting them in danger. (link)

This actually sparked an in-depth discussion with my partner about morality.

Here’s the thing about jellyfish: their senses are not like those of most other animals. Moon jellyfish don’t have eyes or ears.

Their only sense is touch, which they perceive with a simple net of nerves. Though they don’t have a brain, the nerve net is concentrated into some ganglion-like structures. So it’s kind of like their body is controlled by lots of little simple brains which can sense touch.

One way to decide if something is ethical is to ask the questions: “what are the interests of the being/s involved?” and “are they being met or denied?”
As far as we know, a jellyfish’s interests are to get food and to avoid pain and death. They don’t have the mental capacity to feel bored or crowded.

Is it ethical to keep these creatures captive? Well, they aren’t bored or stressed or sick. They will live good long lives. They can’t perceive any difference from their natural habitat. So it is more ethical than keeping say, fish, in a tank.

The fact does remain that they are independent, free living, wild animals. They do not benefit from being removed from their natural habitat.
Just because we are able to do it, does not give us the right to remove animals from the ocean and stick them in a tank.

Tl;dr: these jellies are safe and cannot perceive crowding, but they do not belong to us