Killer whale
Information for offshore regions and warmer waters is more scarce, but widespread sightings indicate the killer whale can survive in most water temperatures. They have been sighted, though more infrequently, in the Mediterranean, the Arabian Sea, the Gulf of Mexico, and the Caribbean. Over 50 individual whales have been documented in the northern Indian Ocean, including two individuals that were sighted in the Persian Gulf in 2008 and off Sri Lanka in 2015. Those orcas may occasionally enter the Red Sea through the Gulf of Aden. The modern status of the species along coastal mainland China and its vicinity is unknown. Recorded sightings have been made from almost the entire shoreline. A wide-ranging population is likely to exist in the central Pacific, with some sightings off Hawaii. Distinct populations may also exist off the west coast of tropical Africa, and Papua New Guinea. In the Mediterranean, killer whales are considered "visitors", likely from the North Atlantic, and sightings become less frequent further east. However, a small year-round population is known to exist in the Strait of Gibraltar, mostly on the Atlantic side. Killer whales also appear to regularly occur off the Galápagos Islands.
Cetacea
Cetaceans () (from Latin "cetus" "whale", from Greek κῆτος "kētos" "huge fish") are aquatic mammals constituting the order cetacea. There are around 89 living species, which are divided into two suborders. The first is the Odontoceti, the toothed whales, which consist of around 70 species, including the dolphin, porpoise, beluga whale, narwhal, sperm whale, and beaked whale. The second is the Mysticeti, the baleen (from Latin "balæna", whale) whales, which have a filter-feeder system, and consist of 15 species divided into 3 families, and include the right whale, bowhead whale, rorqual, pygmy right whale, and gray whale.
The ancient and extinct ancestors of modern whales (Archaeoceti) lived 53 to 45 million years ago. They diverged from even-toed ungulates; their closest living relatives are hippopotamuses and others such as camels and pigs. They were amphibious, and evolved in the shallow waters that separated India from Asia. Around 30 species adapted to a fully oceanic life. Baleen whales split from toothed whales around 34 million years ago.