Answer: Dolphins

If you’ve ever stopped to study the profile of a killer whale—and if you haven’t, then now is the perfect time to check out the picture here and do a little pondering—you might have noticed that the killer “whale” looks more than a little bit like a fat dolphin. That’s because killer whales aren’t in fact whales, but—in a manner of speaking—fat dolphins. Despite their name and large size, killer whales are members of the Delphinidae, or oceanic dolphin, family.

Part of the Cetacea Infraorder, the overarching classification that includes the marine mammals known as dolphins, whales, and porpoises, the Delphinidae family is the most diverse in terms of variation. The family encompasses thirty species, including bottlenose dolphins (and the rest of the dolphins, like the dusky dolphin), narwhals, and porpoises, as well as a number of “whales” like the aforementioned killer whale, the melon-headed whale, the false killer whale, two species of pilot whales, and the pygmy killer whale.

Despite the name of the last one, the smallest member of the family is the Maui dolphin (around 5.5 feet long and 110 pounds). The largest and the subject of today’s question is the Killer Whale (ranging from 16-26 feet in length and weighing between 6,600-13,200 pounds).