Looking at these images one could wonder if this is a picture of a UFO or an alien from another planet, so different is this life from what I see around me every other day.
These photo's where taken at the medusa/jellyfish aquarium at Universeum (a sort of hands-on science museum) in Gothenburg, Swedish west coast. The low light conditions made me use the SMC Pentax-FA 50mm 1:1.4, which is very suited for this sort of conditions.
Yet another reminder that there is always good to have a really fast lens in the bag. This implies a prime lens, zooms are rarely faster than f2.8 and often slower. But even with only one focal length you can usually adapt to that (zoom with your legs), but if the lens is just too slow, you cannot do anything (except turning up the iso to 6400, but that rarely leads to a happy ending).