They are called killer whales because they attac â¦ k and consume whales or other large prey such as seals and sea lions. General description: Adult killer whales generally grow to a length of approximately 27 feet (8.2 m). Females grow to an average length of about 23 feet (7 m).Adults may weigh as much as 10 tons.n 1971, Sea World aquarium in San Diego Ca. got a killer whale, which they named Shamu. In order that the general public would not know how long killer whales live in captivity (which isn't as long as they live in the wild), Sea World names most of their killer whales Shamu.