For each of the folliwng groups of animals (marine invertebrates, marine vertebrates, fresh-water animals & land animals) describe osmosregulatory probkems they face and how they cope with them?

I think what you need can be found at the following 3 sites:

http://en.wikipedia.org/wiki/Osmoregulation

http://72.14.253.104/search?q=cache:cs721WpLCVoJ:www.cbu.edu/~esalgado/BIOL112/Campbell/ch44.doc+osmoregulation+%22land+animals%22+%22marine+animals%22&hl=en&gl=us&ct=clnk&cd=1

http://www.nmc.edu/~ftank/116s05/Ch44WordLectureOutline.htm