Here is a possible concise summary:
The text is about the interactions between orcas and whales, and how orcas can hunt, attack, or sometimes help other marine animals. It also explains some of the strategies that whales use to defend themselves or their calves from orcas, and how human activity has affected both species. It mentions some examples of orca behavior, such as collaborating with whalers, scaring away sea lions, freeing a trapped whale, and fighting with humpback whales. It also discusses some of the theories that scientists have about why orcas do what they do, and how their evolution and diet have changed over time. It concludes by saying that orcas are facing more threats than whales, and that we should worry about their survival.
Here are some key facts extracted from the text:
1. A team of scientists from Western Australia witnessed orcas attacking and killing an adult blue whale in March 2019.
2. Orcas use teamwork, coordination and specific tactics to hunt down large whales, such as biting their fins, pushing their heads underwater, or turning them over on their backs.
3. Female orcas are more likely to lead the attacks on large whales, possibly because they need to feed their young and eat more often than males.
4. Orcas collaborated with whalers in Twofold Bay, Australia, for over a century, alerting them to the presence of larger whales and sharing the carcasses with them.
5. Orcas are sometimes used as scarecrows to deter sea lions from invading ports or eating fish.
6. Orcas have been observed helping other animals from their attacks, such as a humpback whale tangled in fishing gear, or a sunfish.
7. Humpback whales can fight back against orcas, using their tails, flippers and loud noises. They can also protect other animals from orcas, such as seals, sea lions and porpoises.
8. The ancestors of orcas did not hunt very large prey, and only developed the ability to prey on other marine mammals during the Pleistocene period.
9. More than half of the world's orca populations could face extinction in 30 to 50 years due to toxic chemicals that affect their behavior, immune system and reproduction.
10. Orcas are also threatened by ocean noise, which makes hunting more difficult and causes them to metabolize their subcutaneous fat where harmful compounds settle.