Does dolphins look like sharks a little?

only their dorsal fin looks like a shark but they have a long snout and sharks wave their tails side to side while dolphins move their tails up and down, they make high sqeaks, pops and whisltes to send out echoes which is how they find their food when the sound bounce back at them in water they cant see in. (echolocation). sharks are more aggresiive than a dolphin. dolphins will attack a human or something else if they feel threaetened enough. (so dont try to touch them if you see one in the ocean. people have been attacked and killed by dolphins because they scared them and felt threatned.)