سامونڊي مماليا

سيٽئشي (Cetacea) لاطيني "cetus" (سيٽس، يعني وهيل) يا قديم يوناني "κῆτος" (ڪيٽوس، يعني وڏي مڇي يا سامونڊي بلا)، مان ورتل آهي، آرٽيوڊئڪٽائلا (Artiodactyla) آرڊر سان واسطو رکندڙ آبي ممالين جو هڪ انفرا آرڊر آهي، جنهن ۾ وهيل، ڊولفن ۽ پورپوئس شامل آهن.   انھن جي مڪمل طور تي آبي طرز زندگي، منظم جسم جي شڪل، اڪثر وڏي سائز ۽ خاص طور تي گوشت خور غذا، انهن جي اھم خاصيتون آهن. اها پنهنجي دم جي طاقتور مٿان ۽ هيٺ واري حرڪت سان پاڻ کي پاڻيءَ ذريعي اڳتي وڌائين ٿا، پيڊل جهڙي فلڪ ۾ ختم ٿئي ٿي. انهن جا فليپر جي شڪل وارا اڳئين پيرن کي مختلف حرڪتن مثلا موڙڻ، اڇلڻ لاء استعمال ڪندا آهن.

While the majority of cetaceans live in marine environments, a small number reside solely in brackish water or fresh water. Having a cosmopolitan distribution, they can be found in some rivers and all of Earth's oceans, and many species inhabit vast ranges where they migrate with the changing of the seasons.

Cetaceans are famous for their high intelligence, complex social behaviour, and the enormous size of some of the group's members. For example, the blue whale reaches a maximum confirmed length of  and a weight of 173 tonnes (190 short tons), making it the largest animal ever known to have existed.Wood, Gerald The Guinness Book of Animal Facts and Feats (1983) 

There are approximately 89 living species split into two parvorders: Odontoceti or toothed whales (containing porpoises, dolphins, other predatory whales like the  beluga and the sperm whale, and the poorly understood beaked whales) and the filter feeding Mysticeti or baleen whales (which includes species like the blue whale, the humpback whale and the bowhead whale). Despite their highly modified bodies and carnivorous lifestyle, genetic and fossil evidence places cetaceans as nested within even-toed ungulates, most closely related to hippopotamus within the clade Whippomorpha.

Cetaceans have been extensively hunted for their meat, blubber and oil by commercial operations. Although the International Whaling Commission has agreed on putting a halt to commercial whaling, whale hunting is still going on, either under IWC quotas to assist the subsistence of Arctic native people or in the name of scientific research, although a large spectrum of non-lethal methods are now available to study marine mammals in the wild. Cetaceans also face severe environmental hazards from underwater noise pollution, entanglement in abandoned ropes and nets, collisions with ships, plastic and heavy metals build-up, to accelerating climate change, but how much they are affected varies widely from species to species, from minimally in the case of the southern bottlenose whale to the baiji (Chinese river dolphin) which is considered to be functionally extinct due to human activity.

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