Besides the fallacy of humans being part of a whale's diet, there are many factual reasons as to why orcas attack their trainers in captivity. Sometimes, the whales get confused and think that they are just playing with the trainer. They think it is another toy and do not realize that they are actually hurting their trainer. Other times, however, the whales have been pushed to their breaking point. They snap and lash out. This is not because they are monsters; it is because humans have ruined their lives in captivity. The link below shows a video about a very unfortunate incident in which a SeaWorld trainer was killed. Dawn Brancheau had been training whales for years, up until one fatal incident.
http://www.youtube.com/watch?feature=player_embedded&v=nBS7QGHO7oo
As the documentary Blackfish explains, SeaWorld tried to cover up this murder by saying that it was the trainer's fault. They argue that she made a mistake, and the whale was confused. The reality of the situation is that whales should not be kept in captivity nor under the harsh conditions of SeaWorld. The mistake that SeaWorld made in regards to harsh conditions goes all the way back to when SeaWorld was still named Sealand. A whale by the name of Tilikum was held captive and kept in a very small space where he was physically hurt by other whales. According to the PETA organization's article, "Food was withheld from him as a training technique, and he regularly endured painful attacks by two dominant female orcas...He was forced to perform every hour on the hour, eight times a day, seven days a week. The constant stress and exhaustion gave him stomach ulcers." Tilikum is responsible for three deaths, including Dawn Brancheau's, and finally after her death, SeaWorld has decided to stop letting Tilikum participate in shows. He would not have attacked anybody had he not been taken from his home in the ocean, starved and beaten in his small captivity pool, and forced to perform endlessly, day after day. Thus, SeaWorld and other places that keep orcas in captivity are wrongfully putting this beautiful animal on display, making it lash out and seem meaner that it actually is.
One last detail that many people notice while observing a captive killer whale is their dorsal fins. Many of them in captivity are bent over. In the wild, however, these large dorsal fins stand straight up. According to the PETA organization, "Tilikum has a collapsed dorsal fin, a sign of an unhealthy and stressed orca." Killer whales do not normally have flopped-over fins. This is a side-effect of captivity. Thus, you are right to question this physical difference of captive and wild orcas.
References
Associated
Press. (2010, February 4). Trainer Killed by Whale in Front of Spectators.
Associated Press. Retrieved from
http://www.youtube.com/watch?feature=player_embedded&v=nBS7QGHO7oo
Killer
Whale Attacks on Video: Captive Orcas Attack. KeepWhalesWild. (n.d.). Retrieved
from http://www.keepwhaleswild.org/killer-whale-attack-videos.php
Lo, T.
(2012, September 22). One Ocean (Killer Whale Show) @ Sea World. Flickr - Photo
Sharing. Retrieved from
https://www.flickr.com/photos/tammylo/8027930917/in/photolist-depgCJ-dephrY-fzjxFL-6F826D-deoWJ3-depdah-nhp3Rw-nwQKc3-fzjsES-p6gkA-fz55AH-fuvSEF-2aoFM-8dBG3W-cYCXG-dephrg-deph6p-depgLT-depfb2-deoWfc-deph3u-depeES-57AkmC-depdvH-dep84d-depaa6-depeHD-depdVV-depeiC-depbR7-deoVk3-depba2-deoUqs-deoYqz-depasJ-deoWnd-dep8xo-depf3m-deoTTW-depbo5-dep9tY-deoVTj-agT9xh-agTbqJ-agQptn-agQuKg-agQjji-agQhKv-agTeUG-agQw4g/
PETA.
(2014). 30 Years and Three Deaths: Tilikum's Tragic Story. SeaWorld of Hurt.
Retrieved from
http://www.seaworldofhurt.com/features/30-years-three-deaths-tilikums-tragic-story/#ixzz3F1b4RXha
