Being big doesn't mean you're defenseless. Quite the opposite infact, one good tail swipe from these guys could probably break an Orca's bones, all the while their thick tree-like skin protected them to a great degree. They weighed doubled what an Orca did and primarily lived in shallower kelp-infested waters than Orcas were used to swimming in, not to mention the fact that they were known to live in groups and fiercely defended each other as was the case when a hunting boat was repeatedly rammed after attempting to kill a female.