Dolphins have a streamlined fusiform body which has been adapted by evolution to swim fast.
Dolphins are mammals because they breed their babies with milk produced by the mother
While most dolphins look gray, there are some species with black stripes, spots or black parts
Dolphins breath through a hole in the top of the dolphin head which is called blowhole
Dolphin weight varies from species to species. For the smallest dolphin the weight can be 30 Kg. and the largest species like the orca can weight up to 5 tons