JELLYFISH
SENSING Most species of Jellyfish are large enough for humans to see them with the naked eye, but many species are transparent. To make them more visible and for aesthetic effect, they are often kept in aquariums with a dark background and lights to highlight their forms. Jellyfish are visually striking and would be a very aesthetically impressive creature to work with. Sight would be the main way for us to directly experience Jellyfish, not by sound or smell. It would in theory be possible to touch some species (the non-stinging ones) but they have very delicate bodies and would very easily be harmed by this.
COMMUNICATION Vision would perhaps not be the best way to communicate with the Jellyfish, and the only kinds with sophisticated vision (box jellyfish) are mostly too dangerous (painful or deadly stings) and would be difficult to obtain. Touch would be a very effective way to communicate with them and get fast movement reactions, but as already mentioned, they are very delicate and this would have to be done very carefully. Jellyfish also have chemoreceptors that allow them to detect smell and tastes, and would probably be the most effective way to communicate with them (by releasing some sort of food or other substances into their tank).
SPACE A Jellyfish would need to live in a special tank, so that would dictate the kind space we could interact with them in. It would also mean any interaction that is not simply observing them would have to happen indirectly through mechanical/chemical/electronic devices, rather than direct bodily engagement.
SIGNS Jellyfish look very alien and mysterious to humans, as one of the oldest forms of life on earth and evolutionarily extremely distant from us. They are fascinating, beautiful, and are like a glimpse into another world. Some people might also have negative associations with Jellyfish because many species have dangerous stings. They also are a creature that is growing in population and actually thriving due to humans activities such as fishing (eliminating their natural predators) and agricultural runoff.
ETHICS/LIVING CONDITIONS Jellyfish need very specific living conditions to keep them alive, and it would be important to find ways of interacting with them that do not cause them undue damage. There might be a learning curve while we get used to caring for and interacting with them, during which the jellyfish dies and would have to be replaced.
LOGISTICS Jellyfish are not easily obtained, and would need to be purchased either from a supplier, or borrowed from an aquarium collection (public or private). The price of a jellyfish varies depending on which kind it is, but they are not inexpensive. They also require specialised cylindrical acrylic tanks; they will get trapped in the corners of regular rectangular glass tanks. They require constantly flowing water (at specific flow rates depending on type of jellyfish). They live in salt water, so salinity levels need to be considered, as well as pH and temperature specific to the species. The kinds of jellyfish available would live up to a year if well treated. They need to have their water quality tended to at least weekly, and fed 1-2 times a day. They would be fine in an exhibition setting as well as in the lab, for as long as we need, so long there is someone taking care of them.
Jellyfish would be an extremely compelling creature to use for a project, but also quite expensive, difficult, and high-matainance, requiring investing in special equipment (or making it ourselves, which could be fun though challenging.)
Artist Robertina Šebjanič has created interactive artworks with Jellyfish: http://robertina.net/
References:
https://en.wikipedia.org/wiki/Jellyfish
https://en.wikipedia.org/wiki/Box_jellyfish