3/6/2023 0 Comments Orca predators![]() Phylogenetic analysis showed that it is closely related to false killer whales, and lived about 1.5-1.3 million years ago. ![]() The fossil was identified by the authors as a new species, and named Rododelphis stamatiadisi. Part of the study is based on the analysis of the fossil remains of a member of the Delphinidae family, found in 2020 on the island of Rhodes, Greece, by amateur palaeontologist Polychronis Stamatiadis. Their research, published in Current Biology, focussed on two fossils of extinct cetacean species, closely related to present-day killer whales and false killer whales. A team led by Giovanni Bianucci from Università di Pisa, along with researchers from the New York Institute of Technology, has used a multidisciplinary approach to shed light on the question. But, scientists do not fully understand how and when this behaviour may have evolved. Killer whales ( Orcinus orca) and false killer whales ( Pseudorca crassidens) are the only marine mammals that prey on other cetaceans, thanks to their disciplined pack hunting. If so, it would be the first time this law has been applied to a living being.Together with false killer whales, orcas are the only marine mammals that prey on other cetaceans. The latest attempt to get her released could tap into a US law governing the return of objects of cultural importance to Native American peoples. ![]() One of these, which the local Native American people call Sk’aliCh’elh-tenaut, has been in captivity for the past half century. It consists of three inter-related pods, numbering 74 individuals in 2020. Only one population is listed under the Endanger Species Act – the Southern Resident orca, which lives in the Salish Sea off the Pacific Northwest coast. Since August 2019 there are 60 orcas in captivity, of which nearly a third are in the United States. The number of orcas in the wild is thought to be around 50,000. The International Union for Conservation of Nature (IUCN) has categorised orcas as a Data Deficient species, meaning there is not enough information to make a proper assessment of their conservation status. Partly because of their wide distribution, it is unclear how many orcas exist worldwide and whether they are endangered. This would seem to support the “ grandmother hypothesis” in killer whales, which suggests that older females can pass on wisdom and experience without the costs of having more children. It is believed their longevity stems from the fact that they are one of the few animals known to experience the menopause, extending their life well beyond childbearing age. Female orcas have a much longer lifespan, ranging on average between 50 and 80 years. Male orcas live on average between 29 and 60 years. ![]() In fact, their cultures are so distinct, that different populations tend not to interbreed, making them the only known non-human species in which culture shapes evolution. Killer whales also have idiosyncratic vocalisations and communicate in distinct ‘dialects’, with one captive orca, Wikie, being trained to mimic human speech. ![]() Some use bursts of bubbles to herd fish into bait balls, others deliberately strand themselves on beaches to capture the resident seals, and one pod has been seen working together to ambush dolphins. Populations tend to carve out their own specialised niche in a single area, with a particular diet and sophisticated hunting habits. Their behaviour is flexible enough to allow them to live in a range of marine environments in every ocean on Earth. Nevertheless – and despite their common name – they are not a threat to humans and a fatal attack has never been recorded in the wild.Įven for a cetacean, orcas are highly intelligent. Orcas are apex predators, meaning they are at the top of the food chain, and have been known to include fish, seals, rare beaked whales, sharks, birds and even other dolphins in their diet, with no species preying on them. Males, which are bigger than females, can grow up to 8 metres long with a dorsal fin as tall as 1.8 metres. Orcas, or killer whales, are aquatic mammals known as cetaceans and the largest member of the oceanic dolphin family. ![]()
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