why do orcas have collapsed dorsal fins in the wild
Captive killer whales Collapsed or collapsing dorsal fins are rare in most wild populations and usually result from a serious injury to the fin, such as from being shot or colliding with a vessel.[72] After the 1989 Exxon Valdez oil spill, the dorsal fins of two male resident killer whales who had been exposed to the oil collapsed, and the animals subsequently died. In 2002, the dorsal fin of a stranded killer whale showed signs of collapse after three days but regained its natural upright appearance as soon as the orca resumed strong normal swimming upon release.[72]
Finding Nemo Following his birth, Nemo develops a smaller right fin due to damage to his egg, which limits his swimming ability. Worried about Nemo's safety, Marlin embarrasses Nemo during a school field trip. Nemo disobeys his father and sneaks away from the reef towards a boat, and is captured by scuba divers. As the boat departs, a diver accidentally knocks his diving mask overboard. While attempting to save Nemo, Marlin meets Dory, a good-hearted and optimistic regal blue tang with short-term memory loss. Marlin and Dory meet three Australian sharks—Bruce, Anchor, and Chum—who claim to be vegetarians. Marlin discovers the diver's mask and notices an address written on it. When he argues with Dory and accidentally gives her a nosebleed, the blood causes Bruce to lose control of himself and enter a violent feeding frenzy. The pair escape from Bruce, but the mask falls into a trench in the deep sea.