What kind of engineers work at zoos on all the aquariums and life support systems?
And also Im going back to school not for a degree but a shorter continuing education type thing, what kind of fields like that will put me in a zoo?
Work on as in maintaining and repairing? Probably power-engineers. Which is a pretty broad category with many levels, starting primarily at the vocational level, with the highest levels being university degrees.
And then there's sub-qualifications within power-engineering, such as boiler certification, refrigeration certification, etc.
Here at least, there's short vocational type engineering courses, which would be Class 5. Then Class 4 and 3 are 1 and 2 year college diplomas respectively, and then I believe level 2 and above are University level, requiring degrees.
For Aquariums you'd be looking at mechanical pumps, which would fall under Power-engineering most likely.
I'm not sure what you mean by Life-support systems, but if it involved pressurized tanks of any kind again it would fall under Power-Engineering but probably also require boiler certificaiton.