listen to this. scientists are studying whether sharks are able to avoid danger. here with that is cnn's john zarelia. >> a 6-foot sharp. >> we have a nice lemon, guys. >> reporter: the researchers work quickly, taking blood and tissue samples, measurements. university of miami researcher, neil hammershrag is studying the habits of sharks in florida waters. the oil spill has given his company a new more urgent dimension. >> there is the possibility the animals might be able to anticipate the oil or sense the oil and move away from it. it's really unknown right now. >> reporter: this lemon shark will provide valuable data. but when it comes to what hammerslag is looking for, it's, well, a lemon. he's after the great sharks, tigers, hammer heads, bulls. they travel greater distances. if his team lands one, it will be tagged with a satellite