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Orca - Killer whale
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Killer Whales in Cape waters: Skilled hunters
https://africageographic.com/stories/kil...d-hunters/  *This image is copyright of its original author Before ever setting eyes on a killer whale, Dave says that orcas were firmly on his radar. He was intrigued by these creatures – their complex culture, unique dialects that separate different communities and, of course, their cooperative predatory behaviour. “How can one ever forget the footage of a pod of killer whales in the Antarctica swimming side by side to create a perfect wave that washed a seal off an ice flow on which it was seeking refuge, or beaching themselves on the coast of Patagonia in pursuit of seals?” says Dave. He was lucky enough to have access to research by the late Dr Peter Best who shared his tremendous wealth of knowledge about killer whales in Cape waters, but never thought it would form such a large part of his life.  *This image is copyright of its original author His first real life encounter took place right inside Simon’s Town harbour during a historic tour of the dockyard in 1999. “Two killer whales breached literally a few metres in front of my boat leaving me and my guests absolutely stunned. At first I thought that I was hallucinating, but as I watched them gracefully circling the boat it gave time necessary for the experience to sink in,” he reminisces. Having put in the hard yards of research through interest, there they were right next to him. It was another 10 years before his next sighting. “It was the 26 April 2009 – 12h30 to be exact!” with the specificity of a truly life altering experience. “Neptune was smiling at me… [and] for the first time in False Bay, I was privileged to witness and document a pod of killer whales hunting common dolphins – it was just mind-blowing!”  *This image is copyright of its original author Skilled hunters Dave describes this first-hand experience of the hunt in vivid detail. The whales separated a dolphin from its pod, herded it towards the lead hunter and then pummelled it until it swam about, helpless and disoriented. “It was heartbreaking to watch as the huntress locked her jaws on the dolphin and dragged it underwater”, he says. The killer whales then shared the meal amongst themselves. Dave marvels that it was incredible to watch the younger killer whales, while not hunting themselves, observing and studying the action from a distance, acquiring the skills necessary for them to participate. Since that day Dave says he has been privileged to witness over 35 predatory events in the False Bay area. He says that each hunt is unique and that their strategy “responds perfectly to their prey’s flight reaction and always has deadly consequences”.  *This image is copyright of its original author Seasons, location and feeding patterns In False Bay, prey types are present all year round. There are dolphins, large schools of fish like snoek and yellow tail, as well as sharks. Dave says that the False Bay killer whales are present most of year because there is such an abundance of marine life. Worldwide, killer whales are categorised according to their diet: ♦ Transients: marine mammals ♦ Residents: fish ♦ Offshore: sharks and other fish  *This image is copyright of its original author While unable to categorise the False Bay killer whales with absolute certainty, Dave says that there is evidence – pod size, predatory events and observed pod subtleties – that indicate that False Bay has all three ecotypes. Large pods (up to 19 animals) are present during the yellow tail, snoek and tuna season while in autumn, when the common dolphins move inshore to feed, he has observed smaller pods of four to eight whales. Dave goes on to define a third group, and my ears prick up. “Then there are two animals (possibly three) that appear to favour sharks as they have always been sighted in known shark hotspots”, he says.   
Running scared: when predators become prey
Abstract Apex predators play an important role in structuring food webs and are thus key components of healthy, stable ecosystems. While the loss of apex predators has been shown to disrupt ecosystems and trigger trophic cascades, the introduction of novel apex predators to functionally intact systems is less well understood. False Bay, South Africa, is an aggregation site for both white (Carcharodon carcharias ) and broadnose sevengill sharks (Notorynchus cepedianus ) which together fulfill the role of coastal apex predators. However, since 2009, their position at the top of the food chain has been subverted by the increased presence of killer whales (Orcinus orca ) in False Bay. These super predators are known to specialize on certain prey species, and up until 2015 were only documented preying on marine mammals within False Bay. However, in 2015 and 2016 we documented two events in which killer whales preyed upon broadnose sevengill sharks, using a specialized feeding method in which only the liver of each shark was consumed. Although selective feeding on shark liver by killer whales is established, this is the first record of killer whale predations on sevengill sharks in False Bay, and the first documentation of a novel feeding technique, in which killer whales used force applied to the pectoral fins of each shark to rupture the pectoral girdle and thereby access the liver. These predation events resulted in the prolonged absence of sevengill sharks from what is the largest known aggregation site for this species globally, which remained abandoned for up to a month. We briefly review the literature on killer whale behavior, dietary specialization, and population delineation globally and locally, and hypothesize that the novel predations on broadnose sevengill sharks in False Bay are possibly indicative of the arrival of a different sub‐group or ecotype of killer whale in the bay, which habitually feeds on sharks. Due to the unique predatory niche occupied by sevengill sharks in False Bay, the increased presence of these particular killer whales in False Bay could have profound impacts throughout the ecosystem.
Killer whales redistribute white shark foraging pressure on seals
Abstract Predatory behavior and top-down effects in marine ecosystems are well-described, however, intraguild interactions among co-occurring marine top predators remain less understood, but can have far reaching ecological implications. Killer whales and white sharks are prominent upper trophic level predators with highly-overlapping niches, yet their ecological interactions and subsequent effects have remained obscure. Using long-term electronic tagging and survey data we reveal rare and cryptic interactions between these predators at a shared foraging site, Southeast Farallon Island (SEFI). In multiple instances, brief visits from killer whales displaced white sharks from SEFI, disrupting shark feeding behavior for extended periods at this aggregation site. As a result, annual predations of pinnipeds by white sharks at SEFI were negatively correlated with close encounters with killer whales. Tagged white sharks relocated to other aggregation sites, creating detectable increases in white shark density at Ano Nuevo Island. This work highlights the importance of risk effects and intraguild relationships among top ocean predators and the value of long-term data sets revealing these consequential, albeit infrequent, ecological interactions. _______________________________ The same thing seems to be happening in south africa now (08-24-2019, 07:23 PM)Shadow Wrote: This thread is for information, pictures and videos of orcas. When posting only photos, it would be more interesting if there is also some story about that photo if photo doesn´t show something spectacular/extraordinary. 
Check this image of all the populations of orca known at this moment:
 *This image is copyright of its original author Based on this, the biggest orcas are between the Antartic Type A and the Eastern North Atlantic type 2. Also interesting is that one of the smallest of the populations, the Offshore in the northern hemisphere, is the one specialized in sharks, including the great white ones. 
Pablo Cersosimo: " Orca hunting behavior may look cruel but there is a lot of social interaction between the pod members and teaching for the youngest orcas. "
Orcas swimming in the ocean
 *This image is copyright of its original author HUGE Orca from norway  *This image is copyright of its original author orca jumps out of water  *This image is copyright of its original author
(10-21-2020, 02:26 AM)OrcaDaBest Wrote: Orcas swimming in the ocean That photo with fishing boat is optical illusion. If that orca is small, big or huge, who knows, but impossible to say from that photo. Very nice photo though! But of course I could say, that HUGE man in this photo   *This image is copyright of its original author
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