Although there is just one species of Bottlenose Dolphins, there two ecotypes, a coastal variant and a deep-water type. The coastal dolphins are about 9 feet long and weigh 500 pounds, while the deeper dwellers are 12 feet long and weigh about 1000 pounds.
Human and dolphin interactions have occurred since the active creatures were first discovered in the wide oceans. Although there is anecdotal evidence of dolphins helping shipwreck victims and fisherman, more recent interactions are far better documented. Perhaps most interesting is the military’s use of trained dolphins for undersea reconnaissance. Because of their amazingly well-tuned sonar, Dolphins can pick out objects under water and aren’t bothered by competing noises like mechanical sonar is. As a result, they can locate and tag missing equipment, dangers, or even intruders. Along with sea lions, Dolphins are now official members of some naval units.