the dorsal fin of the orca can extend up to six feet above its body. that's taller than most grown men. and because a killer whale swims close to the surface, the dorsal fin can often be seen gliding through the surface of the water. this causes some people to mistake killer whale for sharks. in captivity, dorsal fins often collapse for many reasons, but in the wild, dorsal fin collapse happens in less than one percent of wild orcas.