Orcas get nasty on the great whites in South African seas (survive, look)
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Here on Puget Sound, we've been bemoaning the loss of Orcas due to reduced populations of salmon. Who knew that these lovable marine mammals would be capable of taking on larger prey?
Orcas eat sea lions, walrus, and elephant seals. Nothing is too big for a hungry Orca. They kill white sharks by holding them motionless, upside-down under water until they pass out and then suffocate.
There is almost always something bigger out there. Orcas are just amazingly intelligent.
There’s two distinct groups of orcas In the Puget Sound region. Residents and Transients. Residents eat only salmon and transients eat a wider variety of things… seals sea lions sharks porpoises. Maybe salmon and other fish I don’t know,
I’m not sure there are any actual differences between them or if the differences are entirely habitual and cultural within the group.
Only the residents are threatened. The transients are actually doing quite well. To me it’s a pretty good example of Darwinism in action. One group seems to be a lot more adaptable than the other and one of them will thrive when the other doesn’t.
I had no idea about these things. I do recall a coworker who was former Navy, when learning I'd taken up kayaking, tell me about their marine training manual for scuba divers describing protocols when dealing with marine life while in or on the water. He explained that for each type of marine animal there would be a paragraph to a page instructing behavior. Then he asked me what I thought it might say about orcas, I just shrugged and prompted him. He paused theatrically and said: "Get out of the water."
I laughed, thinking he was joking. Maybe he wasn't ...
Dolphins (orcas are big dolphins dressed in tuxedos) are opportunistic and smart. If something alters the food web enough that one traditional prey item becomes scarce, they'll find another. If some subset of the orca population doesn't make that behavioral/cultural/biological change soon enough, they don't survive. A subset that does will replace them.
If you think about it, when the food regime shifts, available caloric biomass just changes its form. It might have presented itself as a school of smaller fish or juvenile marine mammals before, now more of that same biomass exists in the form of a shark. Nothing acts in isolation. If, for example, commercial krill, forage fish harvest, or changing ocean chemistry reduces that orca population's fish prey and because of international protection sharks become more numerous, why not take advantage of that? Filing their stomachs with multiple smaller fish might present a lower risk of injury but chasing them down probably burns more energy. Once the orca figures out how to avoid being injured by a bigger shark, eating fewer of those larger animals may be a caloric advantage over time.
It also takes the "new" prey time to realize they're being targeted by a new predator. The orca has an advantage until that prey figures out how to defend itself against the new threat.
I worked for Glacier Bay NP&P for 16 years. The bay is visited by orca pods regularly. Harbor seals also breed there. They usually pup close to tidewater glaciers partially because the calved ice floes provide protective haulouts and because the silty water makes it difficult for orcas (who hunt by sight, not sonar) to hunt there. Recently, we began finding harbor seal skins turned inside out in pupping areas. A sign of orca predation. Two interconnected reasons that may be happening. Most of the park's glaciers are in rapid retreat which means less silt ends up flowing into the Bay. As the water slowly gets clearer, it makes it easier for orcas to detect and track seals, so they're learning how to do it closer to glaciers: in pupping areas. Sea otters have re-colonized the Bay, but there hasn't been a huge noticeable increase in orca predation on sea otters. Why? A sea otter is just a mouthful for an orca and they don't have the high caloric blubber layer of a seal. Seals make the better meal.
Last edited by Parnassia; 07-28-2022 at 03:22 PM..
I had no idea about these things. I do recall a coworker who was former Navy, when learning I'd taken up kayaking, tell me about their marine training manual for scuba divers describing protocols when dealing with marine life while in or on the water. He explained that for each type of marine animal there would be a paragraph to a page instructing behavior. Then he asked me what I thought it might say about orcas, I just shrugged and prompted him. He paused theatrically and said: "Get out of the water."
I laughed, thinking he was joking. Maybe he wasn't ...
You wouldn't want to be mistaken for a snack by one who hadn't been able to consume his quota of salmon for the day or week.
Last edited by Ruth4Truth; 07-28-2022 at 03:46 PM..
Given how many of Ma Nature's other kids kill their own meals it seems Orcas are kinda given a bad rap as 'killers'.
Several versions of the reason they got that moniker.
European whalers noted that orcas preyed on large baleen whales...whales they were also targeting. One version says that Basque fisherman referred to orcas as "whale killers" not "killer whales". It was an error in translation.
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Originally Posted by Parnassia
Several versions of the reason they got that moniker.
European whalers noted that orcas preyed on large baleen whales...whales they were also targeting. One version says that Basque fisherman referred to orcas as "whale killers" not "killer whales". It was an error in translation.
Interesting, thanks for this!
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