An orca is a marine mammal. They are often confused for being a whale because of their name ‘killer whale’, however, orcas are actually dolphins. In fact, they are the largest member of the dolphin family!

Why are orcas called 'killer whales' when they are dolphins?

Dolphins and whales are closely related. Orcas were given the name ‘killer whale’ by ancient sailors’ observations of groups of orcas hunting and preying on larger whale species. They called orcas 'asesina ballenas', or ‘whale killer’ – a term that was eventually flipped around to the easier ‘killer whale’. Their Latin name, Orcinus orca, also reflects this observation of orcas feeding on large whales. Orcinus translates to ‘of the kingdom of the dead,’ and orca refers to a kind of whale.

More Info: us.whales.org