Originally, I am a biologist, and I have a biology degree. When I entered university when I was almost 18 years old, my dream was to become a Marine biologist, just like Jacques Cousteau. That changed a bit during my 4 years of studying life as a whole and I ended up in a computer studying genomics. But I had an interesting experience studying something that I still love, cetaceans. I had an internship in a whale-watching group in Brazil, we used to stay for a whole day seated at a top of a hill near the ocean with magnifying glasses searching for cetaceans, and every time we spotted one dolphin or whale we should keep observing it to see what behaviors were noticed. So we used to take notes about the species, and everything. It looks fun? Well, I laughed a bit one of these days when somebody on the radio was telling about whale watching and said " 95% of the time we just watch the water, sometimes we think that we spot a whale, but it is just water". That's true! Many times I used to spend days just watching the water, and the light that reflected the swirls in the sea sometimes confuses us as a whale blow. But still, I could see some nice things while in this internship and also learned a lot.
We usually used to talk a lot about, and Orcas was one of our topics, of course. They are amazing animals, every time we hear new things, we conclude that they have the most similar brains found in nature compared to us. Their social skills, emotions, and thinking power are amazing. People registered one orca carrying a dead calf for 17 days before letting it go  . But one thing that we always brought up is why we call them "Killer whales"? I read that the origin is possibly a bad translation since they hunt in groups to kill bigger whales. Basque fishermen call them "Whale killers" and during the translation, it was inverted  . But still, this name brings a negative sound, people associate that they can be a danger to humans. All people I ask about which animals bring fear are cited together as sharks. But in reality, there isn't any documentation of an Orca's human attack into the wild. Only orcas in these sea animal "zoos" killed humans, and it is known that change a lot of their behavior in captivity. Captivity brings always a big debate, many countries have cetaceans in their captivity, in small sea zoos. Most of them are populated by dolphins. Usually, they reward the dolphins when they make a certain interaction with the humans, but this type of interaction doesn't mean that they would prefer staying there compared to a wild environment.
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Something that also contributed to this image was the 1977's movie "Orca", which came after the great hit "Jaws". Some scientists still call this animal a "Killer Whale" because it is a great predator that preys on all types of animals. But still why not dolphins have the same label? Dolphins are also carnivorous right? So usually people see dolphins as "sweet animals", while orcas are "bad animals". But both occupy a similar position in the food chain. In addition, orcas in addition to sperm whales are closer to dolphins when compared to whales! What we call true whales or baleen whales are from the sub-order Mysticeti while the tooth whales (dolphins, orcas, and sperm whales) are from the sub-order Odontoceti. The interesting thing is that both have the same ancestor, which to your surprise had 4 legs and used to live outside of the water
Whales and dolphins ancestral 
The trick is that the front legs adapted to swimming during evolution, while the back legs just disappeared (some cetaceans still have some remnants of this lost member, small bones found in the back that don't have any other function to the body.
Another big confusion sometimes that causes some fear to people in boats or ships is that they don't know what a whale or dolphin is from a shark. There are lots of differences, but one that can help a lot is seeing the "tail". Sharks and any other fish have vertical fins, while cetaceans have horizontal ones, so if you see a horizontal fin outside of the water, for sure is a whale or dolphin.
Caudal fin from a whale
No horizontal caudal fin in this image, certainty of being a fish, so probably a shark, run 
So orcas, dolphins, whales are amazing, mammals like us, they provide milk to their calves like us! Don't label any of them as bad! Probably they think that most of us are bad for sure.
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