Where are the dolphins?

Interest in extraterrestrial life has tended to focus on a search for extra solar planets similar to the Earth. But what of forms of intelligent life t hat are very different from those found on Earth? Some features of life wil l not be peculiar to our planet, and alien life will resemble ours in such universals. But if intelligent, non-humanoid aliens exist, where might they be? Would they wish to visit Earth and would we know if they did?.