According to Encyclopædia Britannica, a male killer whale can reach a length of more than 26 feet and weigh more than five tons. Females can reach 23 feet and weigh significantly less.
Dolphins are close to the top of their food chain with few natural predators other than sharks. When faced by a predator, dolphins often circle, head butt or use their tails to hit the other animal in self defense. According to the Sarasota Dolphin Research Program, sharks often attack dolphins from behind or below as shown by bite scars.
At 170 to 200 tons, the blue whale is larger than any dinosaur known to have lived. The largest dinosaur lived in the Mesozoic Era and was the Argentinosaurus, which weighed up to 99 tons.